Did volatile halogenated gases from giant salt lakes at the end of the Permian Age lead to a mass extinction of species?
The largest mass extinction in the history of the earth could have been triggered off by giant salt lakes, whose emissions of halogenated gases changed the atmospheric composition so dramatically that vegetation was irretrievably damaged. At least that is what an international team of scientists have reported in the most recent edition of the "Proceedings of the Russian Academy of Sciences". At the Permian/Triassic boundary, 250 million years ago about 90 percent of the animal and plant species ashore became extinct. Previously it was thought that volcanic eruptions, the impacts of asteroids, or methane hydrate were instigating causes. The new theory is based on a comparison with today’s biochemical and atmospheric chemical processes. "Our calculations show that airborne pollutants from giant salt lakes like the Zechstein Sea must have had catastrophic effects at that time", states co-author Dr. Ludwig Weißflog from the Helmholtz-Center for Environmental Research (UFZ). Forecasts predict an increase in the surface areas of deserts and salt lakes due to climate change. That is why the researchers expect that the effects of these halogenated gases will equally increase.
The team of researchers from Russia, Austria, South Africa and Germany investigated whether a process that has been taking place since primordial times on earth could have led to global mass extinctions, particularly at the end of the Permian. The starting point for this theory was their discovery in the south of Russia and South Africa that microbial processes in present-day salt lakes naturally produce and emit highly volatile halocarbons such as chloroform, trichloroethene, and tetrachloroethene. They transcribed these findings to the Zechstein Sea, which about 250 million years ago in the Permian Age, was situated about where present day Central Europe is. The Zechstein Sea with a total surface area of around 600.000 km2 was almost as large as France is today. The hyper saline flat sea at that time was exposed to a predominantly dry continental desert climate and intensive solar radiation - like today’s salt seas. "Consequently, we assume that the climatic, geo-chemical and microbial conditions in the area of the Zechstein Sea were comparable with those of the present day salt seas that we investigated," Weißflog said.
In their current publication the authors explain the similarities between the complex processes of the CO2-cycle in the Permian Age as well as between global warming from that time and at present. Based on comparable calculations from halogenated gas emissions in the atmosphere from present-day salt seas in the south of Russia, the scientists calculated that from the Zechstein Sea alone an annual VHC emissions rate of at least 1.3 million tonnes of trichloroethene, 1.3 million tonnes of tetrachloroethene, 1.1 million tonnes of chloroform as well as 0.050 million tonnes of methyl chloroform can be assumed. By comparison, the annual global industrial emissions of trichloroethene and tetrachloroethene amount to only about 20 percent of that respectively, and only about 5 percent of the chloroform from the emissions calculated for the Zechstein Sea by the scientists. Incidentally, the industrial production of methyl chloroform, which depletes the ozone layer, has been banned since 1987 by regulation of the Montreal Protocol.
"Using steppe plant species we were able to prove that halogenated gases contribute to speeding up desertification: The combination of stress induced by dryness and the simultaneous chemical stressor `halogenated hydrocarbons´ disproportionately damages and destabilize the plants and speeds up the process of erosion," Dr. Karsten Kotte from the University of Heidelberg explained.
Based on both of these findings the researchers were able to form their new hypothesis: At the end of the Permian Age the emissions of halogenated gases from the Zechstein Sea and other salt seas were responsible in a complex chain of events for the world’s largest mass extinction in the history of the earth, in which about 90 percent of the animal and plant species of that time became extinct.
According to the forecast from the International Panel on Climate Change (IPCC), increasing temperatures and aridity due to climate change will also speed up desertification, increasing with it the number and surface area of salt seas, salt lagoons and salt marshlands. Moreover, this will then lead to an increase in naturally formed halogenated gases. The phytotoxic effects of these substances become intensified in conjunction with other atmospheric pollutants and at the same time increasing dryness and exponentiate the eco-toxicological consequences of climate change.
The new theory could be like a jigsaw piece that contributes to solving the puzzle of the largest mass extinction in the history of the earth. "The question as to whether the halogenated gases from the giant salt lakes alone were responsible for it or whether it was a combination of various factors with volcanic eruptions, the impact of asteroids, or methane hydrate equally playing their role still remains unanswered," Ludwig Weißflog said. What is fact however is that the effects of salt seas were previously underestimated. In their publication the researchers working with Dr. Ludwig Weißflog from the UFZ and Dr. Karsten Kotte from the University of Heidelberg want to prove that recent salt lakes and salt deserts of south-east Europe, Middle Asia, Australia, Africa, America can not only influence the regional but also the global climate. The new findings on the effects of these halogenated gases are important for revising climate models, which form the basis for climate forecasts.
Showing posts with label China. Show all posts
Showing posts with label China. Show all posts
Food security for leaf-cutting ants
Workers and their fungus garden reject endophyte invaders
New diseases directly affect human survival and food security, especially as population density climbs. Leaf-cutting ants, one of a few groups of social insects to cultivate crops, have harvested plant material to fertilize their underground fungal gardens for 50 million years. New results from the Smithsonian show that both the ants and their fungal crop actively combat fungi coming into the nest inside leaves, thus ensuring the health of their mutualism.
"When you look at a healthy tropical plant, you think you're seeing just one organism, but each leaf can have dozens of fungal species growing inside, some of which may protect the plant by excluding pathogens," explains Sunshine Van Bael, post-doctoral fellow at the Smithsonian Tropical Research Institute. The fungi growing inside leaves without causing disease to the plant are called endophytes: endo-, inside, and –phyte, plant.
"We knew that leaf cutter ants practice phenomenal garden hygiene. But we wondered if the fungi in leaves might make them less attractive to ants, and thereby protect the plant from leaf cutter ant invasion. Also, since most leaves in nature have endophytic fungi, we wondered how the ants' leaf preparation process might affect the passage of endophytes into the nest."
Van Bael and colleagues used laboratory colonies of one leaf cutter ant species, Atta colombica, to test the ants' response to leaves from a tropical vine, Merremia umbellata, in which they had experimentally manipulated the densities of one fungal endophyte species, Glomerella cingulata, in order to present the ants with leaves containing either high or low levels of fungus. They also pitted 32 additional endophytic fungal strains against cultures of the garden cultivar in Petri plates to find out if they would restrict each others' growth.
Ants cut leaves that contained both high or low levels of fungi, but they took longer to cut leaves from the high endophyte treatment. Moreover, the leaf preparation process by the ants significantly lowered the amount of fungi in leaf pieces before they were placed into the fungal garden. The Petri plate experiment also showed that the garden fungus reduced the growth rate for 28 of the 32 endophytic fungal strains that were tested, with a stronger effect for more rapidly growing endophyte strains. This suggests that, apart from the hygiene practiced by the ants, the garden itself can compete with incoming microbes.
"Fungi in the leaves were not welcome in the leaf cutter ants' garden," concluded Van Bael.
New diseases directly affect human survival and food security, especially as population density climbs. Leaf-cutting ants, one of a few groups of social insects to cultivate crops, have harvested plant material to fertilize their underground fungal gardens for 50 million years. New results from the Smithsonian show that both the ants and their fungal crop actively combat fungi coming into the nest inside leaves, thus ensuring the health of their mutualism.
"When you look at a healthy tropical plant, you think you're seeing just one organism, but each leaf can have dozens of fungal species growing inside, some of which may protect the plant by excluding pathogens," explains Sunshine Van Bael, post-doctoral fellow at the Smithsonian Tropical Research Institute. The fungi growing inside leaves without causing disease to the plant are called endophytes: endo-, inside, and –phyte, plant.
"We knew that leaf cutter ants practice phenomenal garden hygiene. But we wondered if the fungi in leaves might make them less attractive to ants, and thereby protect the plant from leaf cutter ant invasion. Also, since most leaves in nature have endophytic fungi, we wondered how the ants' leaf preparation process might affect the passage of endophytes into the nest."
Van Bael and colleagues used laboratory colonies of one leaf cutter ant species, Atta colombica, to test the ants' response to leaves from a tropical vine, Merremia umbellata, in which they had experimentally manipulated the densities of one fungal endophyte species, Glomerella cingulata, in order to present the ants with leaves containing either high or low levels of fungus. They also pitted 32 additional endophytic fungal strains against cultures of the garden cultivar in Petri plates to find out if they would restrict each others' growth.
Ants cut leaves that contained both high or low levels of fungi, but they took longer to cut leaves from the high endophyte treatment. Moreover, the leaf preparation process by the ants significantly lowered the amount of fungi in leaf pieces before they were placed into the fungal garden. The Petri plate experiment also showed that the garden fungus reduced the growth rate for 28 of the 32 endophytic fungal strains that were tested, with a stronger effect for more rapidly growing endophyte strains. This suggests that, apart from the hygiene practiced by the ants, the garden itself can compete with incoming microbes.
"Fungi in the leaves were not welcome in the leaf cutter ants' garden," concluded Van Bael.
Strong Impact Made on the Amazonia by its Economic Growth Model
The report, Environment Outlook in the Amazonia: GEO Amazonia, uncovers a revealing panorama of accelerated ecosystem transformation and a marked environmental degradation in this vast region of the South American humid tropics - shared by Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname and Venezuela - which is also the planet's most extensive forest zone. The study, prepared by the eight Amazonian countries, with the support of the United Nations Environment Programme (UNEP) and the Amazon Cooperation Treaty Organisation (ACTO), is a new publication in UNEP's series of integrated environmental assessments, also known as GEO (Global Environment Outlook) reports, and on which more than 150 experts, researchers, academics and scientists in the countries of the assessed region participated.
During the preparation of this report, the principal stakeholders from the eight Amazonian countries met to discuss the future outlook of the regional environment. They reached a consensus, clearly expressed in the text: "Our Amazonia is changing at an accelerated rate with very profound modifications in its ecosystems".
After more than two years of analysis, the experts affirm that a joint action of the Amazonian governments in the following areas could enable the region to face the challenges (of the changing environment) – construction of an integrated environmental vision for Amazonia, and definition of a role of the region in national development; harmonisation of environmental policies on regionally relevant themes; design and application of instruments for integrated environmental management; regional strategies that allow sustainable utilisation of Amazonian ecosystems; insertion of risk management in the public agenda; strengthening of Amazonian environmental institutions; increased effort on environmental information production and dissemination in the region; promotion of studies and the economic value of Amazonian environmental services; and designing of a monitoring and evaluation system of policies, programmes and projects.
So far, the effort of the Amazonian countries concerning the management of environmental problems has primarily been reflected in progress related to the development of national instruments for planning and management of Amazonia.
Figures to be considered
In essence, the publication points out that the growing environmental degradation in the Amazonia can be seen by the advance of deforestation, the loss of biodiversity, and localised climate change impacts.
The way in which economic activities, infrastructure construction, and the establishment of human settlements are changing Amazonian land use has resulted in an accelerated transformation of the region's ecosystems. By 2005, accumulated deforestation in Amazonia was 857,666 km2, reducing the region's vegetation cover by approximately 17 per cent. This is equal to two-thirds of Peruvian or 94 per cent of Venezuelan territory.
The loss of biodiversity is expressed in an increased number of endangered species. GEO Amazonia, however, points out that, while local information is available on the different countries' biodiversity, there are no statistics or any general cartography available showing the updated information about this problem for the whole region.
Concerning water resources, note is taken of the importance of the Amazonia because of its value in the continental and global water balance, but the publication reports that limited action is taken on the basin's integrated management. The volume of water captured by the Amazonia basin-from 12,000 to 16,000 km3 a year-represents about 20 per cent of the world's total fresh water.
The availability of surface water in the Amazonia basin depends to a large extent on it being properly used and managed in each of the basin countries. These waters are being affected by different anthropogenic activities that damage its quality: mine waste, hydrocarbon spills, use of agrochemicals, cities' solid wastes, and wastes resulting from processing illicit crops such as coca.
The demands of international markets are putting pressure on the region's economic-productive dynamics, which leads to the intensive use of its natural resources. This results in exploiting timber and non-timber forest products (chestnut in particular) and hydrocarbons, and in expanding mining, agriculture and cattle raising to meet the demands for commodities by globalised markets and encouraging the adoption of a production model which, for the most part, takes no account of sustainable use criteria.
The publication mentions that growing populations, expanding economic activities and building infrastructure have led to a significant change in the region's land use, causing ecosystem fragmentation, deforestation and loss of biodiversity. For example, over a 30-year period (1975-2005), in Brazilian Amazonia the road network multiplied by 10, thus encouraging the establishment of human settlements. The study comments that increased biofuel production could accelerate this land use change.
Amazonia has also experienced accelerated and unplanned urbanisation. Of the population of 33.5 million, approximately 21.3 million, 63.6 per cent of the total population, live in urban areas, indicating how important urbanisation is to the region's sustainable development strategy.
Climate change and extreme events are putting pressure on the Amazonian ecosystems and making it more vulnerable. The region has been affected by a rise in average temperature, although the extent differs depending on the zone. The level of precipitation has also changed although the trends are not very clear.
GEO Amazonia maintains that deforestation in the zone may be having an affect on the regional climate. If the loss of forests exceeds 30 per cent of the vegetation cover, then rainfall levels will decrease; this will produce a vicious circle that favours forest burning, reduces water vapour release, and increases smoke emissions into the atmosphere, resulting in further reduced precipitation. Because of deforestation, Amazonia is progressively becoming a significant contributor to greenhouse gas emissions.
The publication brings together the results of the Nepstad (2007) study projecting that 55 per cent of the humid Amazonian forest will have been lost by 2030 with the subsequent conversion of a large part of Amazonia into a savannah before the end of the 21st century.
Scenarios
The study considers four possible scenarios for 2026 which, along general lines, show that the development style chosen by the Amazonian countries and their citizens is limiting both the options for the region's future sustainable development and the hope of creating an alternative future for the Amazonia. The publication points out that while it will be impossible to entirely conserve the integrity of the Amazonian ecosystems, the different decisions taken today will be of fundamental importance in determining to what degree citizens of the Amazonia would accept exchanging environmental degradation for socio-economic development.
Lines of Action
The publication suggests different ways of proceeding, based on joint action by the Amazonian governments, to allow them to confront the challenges posed by the region. Its main challenges are: have an integrated Amazonian vision and define the region's national development role; harmonise environmental policies on themes relevant to the region; design and implement integrated environmental management instruments; design and implement regional strategies that allow sustainable use of the Amazonian ecosystems; include risk management in the public agenda; strengthen efforts in the region to produce and disseminate environmental information; promote economic valorisation studies and action on Amazonian environmental services; and design a monitoring and assessment system on the impact of policies, programmes and projects.
How countries respond
The governments of Amazonian countries have also made efforts to manage environmental problems. In fact, some progress has been made on national instruments designed for the region's management. In general, the countries have sustainable development plans, sub-national development strategies, ecological economic zoning instruments, as well as sub-national programmes and projects for the Amazonian part of their territory. In all Amazonian countries, the Constitution includes an article on the right to a healthy environment, with a clear mandate as to how the environment should be used and managed.
Countries in the Andean Community of Nations (CAN), including Andean-Amazonian countries like Bolivia, Colombia, Ecuador and Peru, have adopted different agreements on the environment, and on promoting national strategies in their respective countries.
In addition, Brazil has a project on monitoring Amazonian deforestation that is one of the world's most advanced on real-time deforestation monitoring. Also to be highlighted is the establishment of the Amazonian Fund with regulations on investing in action to prevent, monitor and combat deforestation.
As far as water is concerned, ACTO has begun a process to discuss and design, together with UNEP, GEF and OAS, a programme to tackle the challenge of regional water resources management.
During the preparation of this report, the principal stakeholders from the eight Amazonian countries met to discuss the future outlook of the regional environment. They reached a consensus, clearly expressed in the text: "Our Amazonia is changing at an accelerated rate with very profound modifications in its ecosystems".
After more than two years of analysis, the experts affirm that a joint action of the Amazonian governments in the following areas could enable the region to face the challenges (of the changing environment) – construction of an integrated environmental vision for Amazonia, and definition of a role of the region in national development; harmonisation of environmental policies on regionally relevant themes; design and application of instruments for integrated environmental management; regional strategies that allow sustainable utilisation of Amazonian ecosystems; insertion of risk management in the public agenda; strengthening of Amazonian environmental institutions; increased effort on environmental information production and dissemination in the region; promotion of studies and the economic value of Amazonian environmental services; and designing of a monitoring and evaluation system of policies, programmes and projects.
So far, the effort of the Amazonian countries concerning the management of environmental problems has primarily been reflected in progress related to the development of national instruments for planning and management of Amazonia.
Figures to be considered
In essence, the publication points out that the growing environmental degradation in the Amazonia can be seen by the advance of deforestation, the loss of biodiversity, and localised climate change impacts.
The way in which economic activities, infrastructure construction, and the establishment of human settlements are changing Amazonian land use has resulted in an accelerated transformation of the region's ecosystems. By 2005, accumulated deforestation in Amazonia was 857,666 km2, reducing the region's vegetation cover by approximately 17 per cent. This is equal to two-thirds of Peruvian or 94 per cent of Venezuelan territory.
The loss of biodiversity is expressed in an increased number of endangered species. GEO Amazonia, however, points out that, while local information is available on the different countries' biodiversity, there are no statistics or any general cartography available showing the updated information about this problem for the whole region.
Concerning water resources, note is taken of the importance of the Amazonia because of its value in the continental and global water balance, but the publication reports that limited action is taken on the basin's integrated management. The volume of water captured by the Amazonia basin-from 12,000 to 16,000 km3 a year-represents about 20 per cent of the world's total fresh water.
The availability of surface water in the Amazonia basin depends to a large extent on it being properly used and managed in each of the basin countries. These waters are being affected by different anthropogenic activities that damage its quality: mine waste, hydrocarbon spills, use of agrochemicals, cities' solid wastes, and wastes resulting from processing illicit crops such as coca.
The demands of international markets are putting pressure on the region's economic-productive dynamics, which leads to the intensive use of its natural resources. This results in exploiting timber and non-timber forest products (chestnut in particular) and hydrocarbons, and in expanding mining, agriculture and cattle raising to meet the demands for commodities by globalised markets and encouraging the adoption of a production model which, for the most part, takes no account of sustainable use criteria.
The publication mentions that growing populations, expanding economic activities and building infrastructure have led to a significant change in the region's land use, causing ecosystem fragmentation, deforestation and loss of biodiversity. For example, over a 30-year period (1975-2005), in Brazilian Amazonia the road network multiplied by 10, thus encouraging the establishment of human settlements. The study comments that increased biofuel production could accelerate this land use change.
Amazonia has also experienced accelerated and unplanned urbanisation. Of the population of 33.5 million, approximately 21.3 million, 63.6 per cent of the total population, live in urban areas, indicating how important urbanisation is to the region's sustainable development strategy.
Climate change and extreme events are putting pressure on the Amazonian ecosystems and making it more vulnerable. The region has been affected by a rise in average temperature, although the extent differs depending on the zone. The level of precipitation has also changed although the trends are not very clear.
GEO Amazonia maintains that deforestation in the zone may be having an affect on the regional climate. If the loss of forests exceeds 30 per cent of the vegetation cover, then rainfall levels will decrease; this will produce a vicious circle that favours forest burning, reduces water vapour release, and increases smoke emissions into the atmosphere, resulting in further reduced precipitation. Because of deforestation, Amazonia is progressively becoming a significant contributor to greenhouse gas emissions.
The publication brings together the results of the Nepstad (2007) study projecting that 55 per cent of the humid Amazonian forest will have been lost by 2030 with the subsequent conversion of a large part of Amazonia into a savannah before the end of the 21st century.
Scenarios
The study considers four possible scenarios for 2026 which, along general lines, show that the development style chosen by the Amazonian countries and their citizens is limiting both the options for the region's future sustainable development and the hope of creating an alternative future for the Amazonia. The publication points out that while it will be impossible to entirely conserve the integrity of the Amazonian ecosystems, the different decisions taken today will be of fundamental importance in determining to what degree citizens of the Amazonia would accept exchanging environmental degradation for socio-economic development.
Lines of Action
The publication suggests different ways of proceeding, based on joint action by the Amazonian governments, to allow them to confront the challenges posed by the region. Its main challenges are: have an integrated Amazonian vision and define the region's national development role; harmonise environmental policies on themes relevant to the region; design and implement integrated environmental management instruments; design and implement regional strategies that allow sustainable use of the Amazonian ecosystems; include risk management in the public agenda; strengthen efforts in the region to produce and disseminate environmental information; promote economic valorisation studies and action on Amazonian environmental services; and design a monitoring and assessment system on the impact of policies, programmes and projects.
How countries respond
The governments of Amazonian countries have also made efforts to manage environmental problems. In fact, some progress has been made on national instruments designed for the region's management. In general, the countries have sustainable development plans, sub-national development strategies, ecological economic zoning instruments, as well as sub-national programmes and projects for the Amazonian part of their territory. In all Amazonian countries, the Constitution includes an article on the right to a healthy environment, with a clear mandate as to how the environment should be used and managed.
Countries in the Andean Community of Nations (CAN), including Andean-Amazonian countries like Bolivia, Colombia, Ecuador and Peru, have adopted different agreements on the environment, and on promoting national strategies in their respective countries.
In addition, Brazil has a project on monitoring Amazonian deforestation that is one of the world's most advanced on real-time deforestation monitoring. Also to be highlighted is the establishment of the Amazonian Fund with regulations on investing in action to prevent, monitor and combat deforestation.
As far as water is concerned, ACTO has begun a process to discuss and design, together with UNEP, GEF and OAS, a programme to tackle the challenge of regional water resources management.
Cleaning the Atmosphere of Carbon: African Forests Out Of Balance
Tropical forests hold more living biomass than any other terrestrial ecosystem. A new report in the journal Nature by Lewis et al. shows that not only do trees in intact African tropical forests hold a lot of carbon, they hold more carbon now than they did 40 years ago, a hopeful sign that tropical forests could help to mitigate global warming. In a companion article, Helene Muller-Landau, staff scientist at the Smithsonian Tropical Research Institute, says that understanding the causes of this African forest carbon sink and projecting its future is anything but straightforward.
Growing trees absorb carbon. Dead, decomposing trees release carbon. Researchers expect growth and death to approximately balance each other out in mature, undisturbed forests, and thus for total tree carbon stocks, the carbon held by the trees, to remain approximately constant. Yet Lewis and colleagues discovered that on average each hectare (100 x 100 meters, or 2.2 acres) of apparently mature, undisturbed African forest was increasing in tree carbon stocks by an amount equal to the weight of a small car each year. Previous studies have shown that Amazonian forests also take up carbon, although at somewhat lower rates.
"If you assume that these forests should be in equilibrium, then the best way to explain why trees are growing bigger is anthropogenic global change – the extra carbon dioxide in the atmosphere could essentially be acting as fertiliser." says Muller-Landau, "But it's also possible that tropical forests are still growing back following past clearing or fire or other disturbance. Given increasing evidence that tropical forests have a long history of human occupation, recovery from past disturbance is almost certainly part of the reason these forests are taking up carbon today."
Muller-Landau, who directs a project to monitor carbon budgets in forest study sites worldwide as part of the Smithsonian's Centre for Tropical Forest Science and the HSBC Climate Partnership, advises that this new found sink shouldn't be taken for granted, or presumed to continue indefinitely. "While we still can't explain exactly what is behind this carbon sink, one thing we know for sure is that it can't be a sink forever. Trees and forests just can't keep getting bigger. Tropical forests are buying us a bit more time right now, but we can't count on them to continue to offset our carbon emissions in the future."
Growing trees absorb carbon. Dead, decomposing trees release carbon. Researchers expect growth and death to approximately balance each other out in mature, undisturbed forests, and thus for total tree carbon stocks, the carbon held by the trees, to remain approximately constant. Yet Lewis and colleagues discovered that on average each hectare (100 x 100 meters, or 2.2 acres) of apparently mature, undisturbed African forest was increasing in tree carbon stocks by an amount equal to the weight of a small car each year. Previous studies have shown that Amazonian forests also take up carbon, although at somewhat lower rates.
"If you assume that these forests should be in equilibrium, then the best way to explain why trees are growing bigger is anthropogenic global change – the extra carbon dioxide in the atmosphere could essentially be acting as fertiliser." says Muller-Landau, "But it's also possible that tropical forests are still growing back following past clearing or fire or other disturbance. Given increasing evidence that tropical forests have a long history of human occupation, recovery from past disturbance is almost certainly part of the reason these forests are taking up carbon today."
Muller-Landau, who directs a project to monitor carbon budgets in forest study sites worldwide as part of the Smithsonian's Centre for Tropical Forest Science and the HSBC Climate Partnership, advises that this new found sink shouldn't be taken for granted, or presumed to continue indefinitely. "While we still can't explain exactly what is behind this carbon sink, one thing we know for sure is that it can't be a sink forever. Trees and forests just can't keep getting bigger. Tropical forests are buying us a bit more time right now, but we can't count on them to continue to offset our carbon emissions in the future."
Volcanoes, Not Asteroid, May Have Taken Out the Dinosaurs
The dinosaurs died gradually from climate change caused by a series of severe volcanic eruptions in India at the end of the Cretaceous period, says Gerta Keller, professor of geosciences at Princeton University. This theory contradicts the long-held notion that the dinosaurs died due to climate change when a giant meteor hit the Yucatan region of Mexico.
Keller's theory has not yet been adopted by the broader scientific community, but it is rapidly gaining traction as she and her colleagues, funded by the National Science Foundation, report findings from their field work in India and Mexico. The most significant finding is geologic evidence that the mass extinction and the impact of the giant meteor occurred at two different times.
"The Chicxulub impact hit the Yucatan about 300,000 years before the mass extinction that included the dinosaurs and therefore could not have caused it," Keller says. "We know the age of impact because my team discovered a layer of tiny glass melt-rock spherules in Mexico and Texas." The spherules formed when the rocks were vaporised by the impact and blown into the stratosphere and then rained down over North and Central America. "This glass spherule layer marks the precise time of the impact 300,000 years ago," she notes.
The sediments and fossils in the older sediments below the spherule layer and younger sediments above it reveal how life was affected by the impact.
"We see no change, not a single species died out, so the mass extinction 300,000 years later must have been caused by another catastrophe," Keller says. She's firm in her belief that the other catastrophe was a series of volcanic eruptions in the Deccan Traps, a volcanic mountain range that covers much of India today. The mountains, which today are 12,000 feet high, were much higher in prehistoric times.
"Volcanic eruptions poured out lava flows after lava flows, stacking them like a layer cake," she says. "The total volume in cubic miles was greater than the Rockies and the Sierras combined."
Related research by volcanologists Vincent Courtillot, Steve Self, Mike Widdowson, and Anne Lise Chenet shows the lava eruptions were not continuous but occurred in pulses, with each pulse lasting about ten to at most hundred years, and the pulses were separated by short time periods of quiescence. New results from eight subsurface cores drilled by the Oil and Natural Gas Corporation of India in the Krishna-Godavari Basin of eastern India reveal that at least nine lava flows mark the critical volcanic phase that ended in the mass extinction. This ending phase may have occurred over as little as 10,000 to 100,000 years. For each lava eruption, fire shot in tall columns from fissures in the Earth's surface and lofted gases into the stratosphere while the oozing lava spread sheet-like, or in rivers, up to 650 miles across India, and formed the longest lava flows on Earth.
"Their destructive nature is evident in the marine life record, which decreased by about 50 per cent after the first of these long lava flows," Keller said. "By the time of the last lava flow, the mass extinction was complete."
The sulphur dioxide gas injected into the stratosphere converted to sulphate aerosols that caused climate cooling. The cooling lasted until the sulphate aerosols washed out as acid rain and caused the ocean to acidify in the process.
Research on smaller and more recent eruptions, such as the Laki eruption of Iceland in 1783-1784, clarified for scientists the extreme climate effects of volcanic eruptions and the resulting death and destruction of humans, animals, plants and marine life. In spite of the widespread devastation caused by Laki, mass extinction did not occur. The more recent example of Mt. St. Helen's in Washington State has shown just how quickly a local ecosystem can come back after a volcanic eruption.
Then why did it take Earth's ecosystem half a million years to fully recover after the mass extinction that killed the dinosaurs?
"The answer seems to be the occurrence of at least four additional massive Deccan eruptions about 280,000 years after the mass extinction," Keller says. "After those final eruptions, Earth began a full recovery leading to the evolution of life as we know it."
Keller doesn't disagree with scientists who believe the Chicxulub impact affected climate. The event would certainly have caused earthquakes, tsunamis, regional fires and injected huge quantities of sulphur dioxide into the stratosphere, causing cooling and acidification of the land and oceans. "The difference is that the quantity of gas injection from the main phase of Deccan eruptions was 30 to 100 times larger than the Chicxulub impact and occurred over as little as 10,000 to 100,000 years, with each pulse lasting about 10 years or more."
Up until now, sceptics have doubted whether gas from Deccan-like eruptions reaches the stratosphere, but the relatively small 1783-1784 Laki eruption in Iceland revealed that even rather small eruptions loft gases into the stratosphere.
Until recently, it was also believed that the last phase of Deccan volcanic eruptions occurred over a million-year period, which would have been long enough for the environment to recover between eruptions, thus preventing a runaway extinction effect. Vincent Courtillot and collaborators from the Institut de Physique du Globe de Paris have recently discovered that the main phase of Deccan eruptions was much shorter and culminated near the Cretaceous-Tertiary boundary. Known as the "K-T boundary" to scientists, it marks the end of the Mesozoic Era and is associated with the mass extinction.
Most importantly, field work by Keller and her collaborators revealed that the mass extinction coincided with the end of the main phase of Deccan eruptions suggesting that volcanism is the "smoking gun" that killed the dinosaurs.
"These new discoveries have made the volcanism-mass extinction theory a very viable cause for the end-Cretaceous mass extinction," Keller says.
According to NSF Program Director Harold Lane, "Dr Keller's recent NSF-supported research stokes continued debate about the cause of the near extinction of earth's biota at the end of the Cretaceous, a major event in the history of life on earth."
SOURCE: NATIONAL SCIENCE FOUNDATION
Keller's theory has not yet been adopted by the broader scientific community, but it is rapidly gaining traction as she and her colleagues, funded by the National Science Foundation, report findings from their field work in India and Mexico. The most significant finding is geologic evidence that the mass extinction and the impact of the giant meteor occurred at two different times.
"The Chicxulub impact hit the Yucatan about 300,000 years before the mass extinction that included the dinosaurs and therefore could not have caused it," Keller says. "We know the age of impact because my team discovered a layer of tiny glass melt-rock spherules in Mexico and Texas." The spherules formed when the rocks were vaporised by the impact and blown into the stratosphere and then rained down over North and Central America. "This glass spherule layer marks the precise time of the impact 300,000 years ago," she notes.
The sediments and fossils in the older sediments below the spherule layer and younger sediments above it reveal how life was affected by the impact.
"We see no change, not a single species died out, so the mass extinction 300,000 years later must have been caused by another catastrophe," Keller says. She's firm in her belief that the other catastrophe was a series of volcanic eruptions in the Deccan Traps, a volcanic mountain range that covers much of India today. The mountains, which today are 12,000 feet high, were much higher in prehistoric times.
"Volcanic eruptions poured out lava flows after lava flows, stacking them like a layer cake," she says. "The total volume in cubic miles was greater than the Rockies and the Sierras combined."
Related research by volcanologists Vincent Courtillot, Steve Self, Mike Widdowson, and Anne Lise Chenet shows the lava eruptions were not continuous but occurred in pulses, with each pulse lasting about ten to at most hundred years, and the pulses were separated by short time periods of quiescence. New results from eight subsurface cores drilled by the Oil and Natural Gas Corporation of India in the Krishna-Godavari Basin of eastern India reveal that at least nine lava flows mark the critical volcanic phase that ended in the mass extinction. This ending phase may have occurred over as little as 10,000 to 100,000 years. For each lava eruption, fire shot in tall columns from fissures in the Earth's surface and lofted gases into the stratosphere while the oozing lava spread sheet-like, or in rivers, up to 650 miles across India, and formed the longest lava flows on Earth.
"Their destructive nature is evident in the marine life record, which decreased by about 50 per cent after the first of these long lava flows," Keller said. "By the time of the last lava flow, the mass extinction was complete."
The sulphur dioxide gas injected into the stratosphere converted to sulphate aerosols that caused climate cooling. The cooling lasted until the sulphate aerosols washed out as acid rain and caused the ocean to acidify in the process.
Research on smaller and more recent eruptions, such as the Laki eruption of Iceland in 1783-1784, clarified for scientists the extreme climate effects of volcanic eruptions and the resulting death and destruction of humans, animals, plants and marine life. In spite of the widespread devastation caused by Laki, mass extinction did not occur. The more recent example of Mt. St. Helen's in Washington State has shown just how quickly a local ecosystem can come back after a volcanic eruption.
Then why did it take Earth's ecosystem half a million years to fully recover after the mass extinction that killed the dinosaurs?
"The answer seems to be the occurrence of at least four additional massive Deccan eruptions about 280,000 years after the mass extinction," Keller says. "After those final eruptions, Earth began a full recovery leading to the evolution of life as we know it."
Keller doesn't disagree with scientists who believe the Chicxulub impact affected climate. The event would certainly have caused earthquakes, tsunamis, regional fires and injected huge quantities of sulphur dioxide into the stratosphere, causing cooling and acidification of the land and oceans. "The difference is that the quantity of gas injection from the main phase of Deccan eruptions was 30 to 100 times larger than the Chicxulub impact and occurred over as little as 10,000 to 100,000 years, with each pulse lasting about 10 years or more."
Up until now, sceptics have doubted whether gas from Deccan-like eruptions reaches the stratosphere, but the relatively small 1783-1784 Laki eruption in Iceland revealed that even rather small eruptions loft gases into the stratosphere.
Until recently, it was also believed that the last phase of Deccan volcanic eruptions occurred over a million-year period, which would have been long enough for the environment to recover between eruptions, thus preventing a runaway extinction effect. Vincent Courtillot and collaborators from the Institut de Physique du Globe de Paris have recently discovered that the main phase of Deccan eruptions was much shorter and culminated near the Cretaceous-Tertiary boundary. Known as the "K-T boundary" to scientists, it marks the end of the Mesozoic Era and is associated with the mass extinction.
Most importantly, field work by Keller and her collaborators revealed that the mass extinction coincided with the end of the main phase of Deccan eruptions suggesting that volcanism is the "smoking gun" that killed the dinosaurs.
"These new discoveries have made the volcanism-mass extinction theory a very viable cause for the end-Cretaceous mass extinction," Keller says.
According to NSF Program Director Harold Lane, "Dr Keller's recent NSF-supported research stokes continued debate about the cause of the near extinction of earth's biota at the end of the Cretaceous, a major event in the history of life on earth."
SOURCE: NATIONAL SCIENCE FOUNDATION
Genetic Adaptations Key to Microbe's Survival in Challenging Environment
The genome of a marine bacterium living 2,500 metres below the ocean's surface is providing clues to how life adapts in extreme thermal and chemical gradients, according to an article published in the journal PLoS Genetics, an open-access publication published by the Public Library of Science.
The research focused on the bacterium Nautilia profundicola, a microbe that survives near deep-sea hydrothermal vents. Micro organisms that thrive at these geysers on the sea floor must adapt to fluctuations in temperature and oxygen levels, ranging from the hot, sulphide and heavy metal-laden plume at the vents' outlets to cold seawater in the surrounding region.
The study combined genome analysis with physiological and ecological observations to investigate the importance of one gene in N. profundicola. That gene, called rgy, allows the bacterium to manufacture a protein called reverse gyrase when it encounters extremely hot fluids from the Earth's interior.
Previous studies found the gene only in micro organisms growing in temperatures greater than 80°C, but N. profundicola thrives best at much lower temperatures.
"The gene's presence in N. profundicola suggests that it might play a role in the bacterium's ability to survive rapid and frequent temperature fluctuations in its environment," said Assistant Professor of Marine Biosciences, Barbara Campbell, the study's lead scientist.
Additional University of Delaware contributors were Professor of Marine Biosciences Stephen Craig Cary, Assistant Professor of Marine Biosciences Thomas Hanson, and Julie Smith, marine biosciences doctoral student. Also collaborating on the project were researchers from the Davis and Riverside campuses of the University of California; the University of Louisville; the University of Waikato in Hamilton, New Zealand; and the J. Craig Venter Institute in Rockville, Md.
The researchers also uncovered further adaptations to the vent environment, including genes necessary for growth and sensing environmental conditions, and a new route for nitrate assimilation related to how other bacteria use ammonia as an energy source. Photosynthesis cannot occur in the hydrothermal vents' dark environment, where hot, toxic fluids oozing from below the seafloor combine with cold seawater at very high pressures.
These results help to explain how microbes survive near the vents, where conditions are thought to resemble those found on early Earth. Nautilia profundicola contains all the genes necessary for life in conditions widely believed to mimic those in our planet's early biosphere and could aid in understanding of how life evolved.
"It will be an important model system," Campbell said, "for understanding early microbial life on Earth."
The research focused on the bacterium Nautilia profundicola, a microbe that survives near deep-sea hydrothermal vents. Micro organisms that thrive at these geysers on the sea floor must adapt to fluctuations in temperature and oxygen levels, ranging from the hot, sulphide and heavy metal-laden plume at the vents' outlets to cold seawater in the surrounding region.
The study combined genome analysis with physiological and ecological observations to investigate the importance of one gene in N. profundicola. That gene, called rgy, allows the bacterium to manufacture a protein called reverse gyrase when it encounters extremely hot fluids from the Earth's interior.
Previous studies found the gene only in micro organisms growing in temperatures greater than 80°C, but N. profundicola thrives best at much lower temperatures.
"The gene's presence in N. profundicola suggests that it might play a role in the bacterium's ability to survive rapid and frequent temperature fluctuations in its environment," said Assistant Professor of Marine Biosciences, Barbara Campbell, the study's lead scientist.
Additional University of Delaware contributors were Professor of Marine Biosciences Stephen Craig Cary, Assistant Professor of Marine Biosciences Thomas Hanson, and Julie Smith, marine biosciences doctoral student. Also collaborating on the project were researchers from the Davis and Riverside campuses of the University of California; the University of Louisville; the University of Waikato in Hamilton, New Zealand; and the J. Craig Venter Institute in Rockville, Md.
The researchers also uncovered further adaptations to the vent environment, including genes necessary for growth and sensing environmental conditions, and a new route for nitrate assimilation related to how other bacteria use ammonia as an energy source. Photosynthesis cannot occur in the hydrothermal vents' dark environment, where hot, toxic fluids oozing from below the seafloor combine with cold seawater at very high pressures.
These results help to explain how microbes survive near the vents, where conditions are thought to resemble those found on early Earth. Nautilia profundicola contains all the genes necessary for life in conditions widely believed to mimic those in our planet's early biosphere and could aid in understanding of how life evolved.
"It will be an important model system," Campbell said, "for understanding early microbial life on Earth."
Amazon Could Prosper Thanks To Emission Payments, Be Lost Without: WWF
Global payments for ecological services rendered by the Amazon such as the carbon retaining in its forests could go a long way to preserving them, a new study has found.
Keeping the Amazon forests standing: a matter of values, a study carried by the Copernicus Institute of the University of Utrecht on behalf of WWF, valued the avoided emissions from deforestation or degradation over large areas of the Amazon at between 55 and 78 Euro per hectare per year.
These include erosion protection (up to 185 Euro per hectare per year), pollination services by rainforest insects (38 Euro per hectare per year in Ecuadorian coffee plantations), forest products such as honey, fruits and mushrooms (40-80 Euro) and ecotourism (2.5 -5.5 Euro).
This compares to the returns from the production of commodities as beef and soya, the main Amazonian products imported by Europe. Soya generates 230 to 470 Euro per hectare annually and cattle breeding adds up 40 to 115 Euro per hectare per year.
While the major areas of Brazilian soya production are outside the Amazon, the economic interest for this commodity is adding to pressure in the region.
The WWF report shows that the revenue currently received from economic activities in which the natural environment remains intact is not high enough to offset the non-sustainable activities, but finding mechanisms to secure global payments for the forest's ecological services would be a major impetus to both preserving the forest and paying for and providing for proper management.
The key emerging likely mechanism as the world tackles climate change is the s so-called REDD mechanism (Reduced Emissions from Deforestation and forest Degradation) where industrialised countries would pay for forest preservation and the combating of CO2 emissions in tropical countries.
The plans for this mechanism allow for large money flows to become available for sustainable forest management, which will also benefit local communities such as the native population of the Amazon region.
Johan van de Gronden, General Manager of WWF-Netherlands, comments: “REDD is not the only mechanism for the realisation of sustainable forest management, but certainly the one that is the most promising.’’
WWF Brazil emphasised the importance of tackling issues at the receiving end of any REDD mechanism, such as the lack of clarity concerning land ownership, the illegal occupation of land and the illegal land market.
“National and international companies should also play a role of leadership, selecting their suppliers and cleaning and decarbonising their productive chains thus participating actively of the sustainable development of the Amazon”, said Denise Hamú, CEO of WWF-Brazil.
As the fourth-largest trade partner of Brazil, the Netherlands is a major contributor to the destruction of the rainforests. For example, the country is the largest importer of soya in the world after China.
“Humans are very dependent on the services provided by the Amazon region that are disappearing rapidly but for which we are not paying as yet: rain for agriculture, clean drinking water, pure air and the combating of global warming,” said Van de Gronden.
“Especially because of its large contribution to the Brazilian economy, the Netherlands can play a leading role in stimulating a sustainable economic development of the Amazon region by choosing to import sustainable produced goods such as FSC-certified timber only.’’
Keeping the Amazon forests standing: a matter of values, a study carried by the Copernicus Institute of the University of Utrecht on behalf of WWF, valued the avoided emissions from deforestation or degradation over large areas of the Amazon at between 55 and 78 Euro per hectare per year.
These include erosion protection (up to 185 Euro per hectare per year), pollination services by rainforest insects (38 Euro per hectare per year in Ecuadorian coffee plantations), forest products such as honey, fruits and mushrooms (40-80 Euro) and ecotourism (2.5 -5.5 Euro).
This compares to the returns from the production of commodities as beef and soya, the main Amazonian products imported by Europe. Soya generates 230 to 470 Euro per hectare annually and cattle breeding adds up 40 to 115 Euro per hectare per year.
While the major areas of Brazilian soya production are outside the Amazon, the economic interest for this commodity is adding to pressure in the region.
The WWF report shows that the revenue currently received from economic activities in which the natural environment remains intact is not high enough to offset the non-sustainable activities, but finding mechanisms to secure global payments for the forest's ecological services would be a major impetus to both preserving the forest and paying for and providing for proper management.
The key emerging likely mechanism as the world tackles climate change is the s so-called REDD mechanism (Reduced Emissions from Deforestation and forest Degradation) where industrialised countries would pay for forest preservation and the combating of CO2 emissions in tropical countries.
The plans for this mechanism allow for large money flows to become available for sustainable forest management, which will also benefit local communities such as the native population of the Amazon region.
Johan van de Gronden, General Manager of WWF-Netherlands, comments: “REDD is not the only mechanism for the realisation of sustainable forest management, but certainly the one that is the most promising.’’
WWF Brazil emphasised the importance of tackling issues at the receiving end of any REDD mechanism, such as the lack of clarity concerning land ownership, the illegal occupation of land and the illegal land market.
“National and international companies should also play a role of leadership, selecting their suppliers and cleaning and decarbonising their productive chains thus participating actively of the sustainable development of the Amazon”, said Denise Hamú, CEO of WWF-Brazil.
As the fourth-largest trade partner of Brazil, the Netherlands is a major contributor to the destruction of the rainforests. For example, the country is the largest importer of soya in the world after China.
“Humans are very dependent on the services provided by the Amazon region that are disappearing rapidly but for which we are not paying as yet: rain for agriculture, clean drinking water, pure air and the combating of global warming,” said Van de Gronden.
“Especially because of its large contribution to the Brazilian economy, the Netherlands can play a leading role in stimulating a sustainable economic development of the Amazon region by choosing to import sustainable produced goods such as FSC-certified timber only.’’
High CO2 Boosts Plant Respiration, Potentially Affecting Climate and Crops
The leaves of soybeans grown at the elevated carbon dioxide (CO2) levels predicted for the year 2050 respire more than those grown under current atmospheric conditions, researchers report, a finding that will help fine-tune climate models and could point to increased crop yields as CO2 levels rise.
The study, from researchers at the University of Illinois and the US Department of Agriculture, appears in the Proceedings of the National Academy of Sciences.
Plants draw CO2 from the atmosphere and make sugars through the process of photosynthesis. But they also release some CO2 during respiration as they use the sugars to generate energy for self-maintenance and growth. How elevated CO2 affects plant respiration will therefore influence future food supplies and the extent to which plants can capture CO2 from the air and store it as carbon in their tissues.
While there is broad agreement that higher atmospheric CO2 levels stimulate photosynthesis in C3 plants, such as soybean, no such consensus exists on how rising CO2 levels will affect plant respiration.
"There's been a great deal of controversy about how plant respiration responds to elevated CO2," said University of Illinois plant biology professor Andrew Leakey, who led the study. "Some summary studies suggest it will go down by 18 per cent, some suggest it won't change, and some suggest it will increase as much as 11 per cent."
Understanding how the respiratory pathway responds when plants are grown at elevated CO2 is the key to reducing this uncertainty, Leakey said. His team used micro arrays, a genomic tool that can detect changes in the activity of thousands of genes at a time, to learn which genes in the high CO2 plants were being switched on at higher or lower levels than those of the soybeans grown at current CO2 levels.
Rather than assessing plants grown in chambers in a greenhouse, as most studies have done, Leakey's team made use of the Soybean Free Air Concentration Enrichment (Soy FACE) facility at Illinois. This open-air research lab can expose a soybean field to a variety of atmospheric CO2 levels without isolating the plants from other environmental influences, such as rainfall, sunlight and insects.
Some of the plants were exposed to atmospheric CO2 levels of 550 parts per million (ppm), the level predicted for the year 2050 if current trends continue. These were compared to plants grown at ambient CO2 levels (380 ppm).
The results were striking. At least 90 different genes coding the majority of enzymes in the cascade of chemical reactions that govern respiration were switched on (expressed) at higher levels in the soybeans grown at high CO2 levels. This explained how the plants were able to use the increased supply of sugars from stimulated photosynthesis under high CO2 conditions to produce energy, Leakey said. The rate of respiration increased 37 per cent at the elevated CO2 levels.
The enhanced respiration is likely to support greater transport of sugars from leaves to other growing parts of the plant, including the seeds, Leakey said.
"The expression of over 600 genes was altered by elevated CO2 in total, which will help us to understand how the response is regulated and also hopefully produce crops that will perform better in the future," he said.
The study, from researchers at the University of Illinois and the US Department of Agriculture, appears in the Proceedings of the National Academy of Sciences.
Plants draw CO2 from the atmosphere and make sugars through the process of photosynthesis. But they also release some CO2 during respiration as they use the sugars to generate energy for self-maintenance and growth. How elevated CO2 affects plant respiration will therefore influence future food supplies and the extent to which plants can capture CO2 from the air and store it as carbon in their tissues.
While there is broad agreement that higher atmospheric CO2 levels stimulate photosynthesis in C3 plants, such as soybean, no such consensus exists on how rising CO2 levels will affect plant respiration.
"There's been a great deal of controversy about how plant respiration responds to elevated CO2," said University of Illinois plant biology professor Andrew Leakey, who led the study. "Some summary studies suggest it will go down by 18 per cent, some suggest it won't change, and some suggest it will increase as much as 11 per cent."
Understanding how the respiratory pathway responds when plants are grown at elevated CO2 is the key to reducing this uncertainty, Leakey said. His team used micro arrays, a genomic tool that can detect changes in the activity of thousands of genes at a time, to learn which genes in the high CO2 plants were being switched on at higher or lower levels than those of the soybeans grown at current CO2 levels.
Rather than assessing plants grown in chambers in a greenhouse, as most studies have done, Leakey's team made use of the Soybean Free Air Concentration Enrichment (Soy FACE) facility at Illinois. This open-air research lab can expose a soybean field to a variety of atmospheric CO2 levels without isolating the plants from other environmental influences, such as rainfall, sunlight and insects.
Some of the plants were exposed to atmospheric CO2 levels of 550 parts per million (ppm), the level predicted for the year 2050 if current trends continue. These were compared to plants grown at ambient CO2 levels (380 ppm).
The results were striking. At least 90 different genes coding the majority of enzymes in the cascade of chemical reactions that govern respiration were switched on (expressed) at higher levels in the soybeans grown at high CO2 levels. This explained how the plants were able to use the increased supply of sugars from stimulated photosynthesis under high CO2 conditions to produce energy, Leakey said. The rate of respiration increased 37 per cent at the elevated CO2 levels.
The enhanced respiration is likely to support greater transport of sugars from leaves to other growing parts of the plant, including the seeds, Leakey said.
"The expression of over 600 genes was altered by elevated CO2 in total, which will help us to understand how the response is regulated and also hopefully produce crops that will perform better in the future," he said.
Scientists Uncover a Dramatic Rise in Sea Level and Its Broad Ramifications
Scientists have found proof in Bermuda that the planet’s sea level was once more than 21 metres (70 feet) higher about 400,000 years ago than it is now. Their findings were published in the February 2009 edition of the journal Quaternary Science Reviews.
Storrs Olson, research zoologist at the Smithsonian’s National Museum of Natural History, and geologist Paul Hearty of the Bald Head Island Conservancy discovered sedimentary and fossil evidence in the walls of a limestone quarry in Bermuda that documents a rise in sea level during an interglacial period of the Middle Pleistocene in excess of 21 metres above its current level. Hearty and colleagues had published preliminary evidence of such a sea-level rise nearly a decade ago, which was met with scepticism among geologists. This marine fossil evidence now provides unequivocal evidence of the timing and extent of this event.
The nature of the sediments and fossil accumulation found by Olson and Hearty was not compatible with the deposits left by a tsunami but rather with the gradual, yet relatively rapid, increase in the volume of the planet’s ocean caused by melting ice sheets.
A rise in sea level to such a height would have ramifications well beyond geology and climate modelling. For the organisms of coastal areas, and particularly for low islands and archipelagos, such a rise would have been catastrophic. The Florida peninsula, for example, would have been reduced to a relatively small archipelago along the higher parts of its central ridge.
“We have only to look at Bermuda to begin to assess the impact for terrestrial organisms or seabirds dependant on dry land for nesting sites,” said Olson. “This group of islands in the Atlantic was as compromised as a nesting site for seabirds that at least one species of shearwater became extinct as well as the short-tailed albatross, marking the end of all resident albatrosses in the North Atlantic.”
Determining the timing and extent of this global rise in sea level is not only important for interpreting the influence that it may have had on biogeographical patterns and extinctions of organisms on islands and low-lying continental coastal areas, it is also critical for anticipating the possible effects of future climate change. This particular interglacial period is considered by some scientists to be a suitable comparison to our current interglacial period. With future carbon dioxide levels possibly rising higher than any time in the past million years, it is important to consider the potential effects on polar ice sheets.
Biogeographers, conservationists and many others in the biological sciences must take these findings into consideration, Olson urged. “These findings are incredibly important and have major relevance because of their potential predictive value since this sea-level rise took place during the interglacial period most similar to the present one now in progress. It thus becomes essential that the full extent and duration of this event be more widely recognised and acknowledged.”
Storrs Olson, research zoologist at the Smithsonian’s National Museum of Natural History, and geologist Paul Hearty of the Bald Head Island Conservancy discovered sedimentary and fossil evidence in the walls of a limestone quarry in Bermuda that documents a rise in sea level during an interglacial period of the Middle Pleistocene in excess of 21 metres above its current level. Hearty and colleagues had published preliminary evidence of such a sea-level rise nearly a decade ago, which was met with scepticism among geologists. This marine fossil evidence now provides unequivocal evidence of the timing and extent of this event.
The nature of the sediments and fossil accumulation found by Olson and Hearty was not compatible with the deposits left by a tsunami but rather with the gradual, yet relatively rapid, increase in the volume of the planet’s ocean caused by melting ice sheets.
A rise in sea level to such a height would have ramifications well beyond geology and climate modelling. For the organisms of coastal areas, and particularly for low islands and archipelagos, such a rise would have been catastrophic. The Florida peninsula, for example, would have been reduced to a relatively small archipelago along the higher parts of its central ridge.
“We have only to look at Bermuda to begin to assess the impact for terrestrial organisms or seabirds dependant on dry land for nesting sites,” said Olson. “This group of islands in the Atlantic was as compromised as a nesting site for seabirds that at least one species of shearwater became extinct as well as the short-tailed albatross, marking the end of all resident albatrosses in the North Atlantic.”
Determining the timing and extent of this global rise in sea level is not only important for interpreting the influence that it may have had on biogeographical patterns and extinctions of organisms on islands and low-lying continental coastal areas, it is also critical for anticipating the possible effects of future climate change. This particular interglacial period is considered by some scientists to be a suitable comparison to our current interglacial period. With future carbon dioxide levels possibly rising higher than any time in the past million years, it is important to consider the potential effects on polar ice sheets.
Biogeographers, conservationists and many others in the biological sciences must take these findings into consideration, Olson urged. “These findings are incredibly important and have major relevance because of their potential predictive value since this sea-level rise took place during the interglacial period most similar to the present one now in progress. It thus becomes essential that the full extent and duration of this event be more widely recognised and acknowledged.”
Amazon Deforestation: Earth's Heart and Lungs Dismembered
NSF-supported researchers explore the links between globalisation, deforestation of Brazil’s Amazon region and the country’s dynamic cattle economy
Splintered, charred wood litters the outskirts of an expansive ranch that lies on recently cleared land in the Brazilian Amazon. On the newly planted pasture, cattle leisurely graze, occasionally lifting their heads to gaze past heaps of dead trees towards an island of dense vegetation that has thus far been spared. But it too may soon be cut down.
Such scenes are becoming increasingly common as large swaths of the Brazilian Amazon are being bulldozed and burned to accommodate expanding cattle ranches. Deforestation, which is dismembering the Earth's functional heart and lungs, is largely resulting from cattle ranching driven by economic incentives and demand for Brazilian beef, according to the Centre for International Forestry Research.
"Probably 80 to 90 per cent of all cleared land in the region (the Brazilian Amazon) is attributable to some form of pasture or ranching," said Robert Walker, a geography professor at Michigan State University and an expert on land-use change in the Brazilian Amazon.
Deforestation is accelerating
Brazil has historically had the distinction of serving as the world's leader of deforestation. According to Walker, during the last three decades, an annual average of 6,500 square miles of the Brazilian Amazon, an area that is greater than the size of Connecticut, has been deforested.
Satellite data indicates that the rate of Amazonian deforestation is accelerating; in some areas, the rate increased by 50 per cent since last year. And, with over 20 million people and 70 million cattle now inhabiting the Amazon region, about a 600 per cent increase in the last 60 years, more trees are being razed to make room for cattle ranches, said Walker.
Small-scale ranchers, including poor, subsistence farmers, encroach on forests gradually, felling trees and creating modestly sized pastures in a piecemeal fashion. By contrast, larger land owners use tractors and bulldozers to quickly mow down vast tracts of forest, and then burn remaining vegetation to establish huge ranches. Either way, the landscape ends up fragmented and ecologically devastated.
Ground zero for global extinction
As the world's largest tropical rainforest, the Amazon houses the world's largest collection of living species of plants and animals. It also plays a significant role in stabilising local climate and may provide the raw materials for cures for some of the world's deadliest diseases.
But deforestation has transformed the Amazon into ground zero for global extinction. In addition, burning and rotting trees release carbon dioxide, which contributes greatly to climate change.
"Brazil overall is the fifth or sixth largest emitter of carbon dioxide and, by far, the most important source is deforestation," said Eugenio Arima, an assistant professor of environmental studies at Hobart and William Smith Colleges and a former conservation and development researcher at the Brazilian non-profit institute Imazon.
The cattle economy
With support from the National Science Foundation, Walker and Arima are currently researching Brazil's dynamic cattle economy; their research is exposing links between globalisation and deforestation.
According to Walker and Arima's research, reduced transportation costs from the construction of highways in the Amazon, together with the rise in beef prices, provided economic incentives to increase cattle grazing in the region. In addition, the devaluation of the Brazilian real decreased the costs of importing beef from Brazil, and efforts to reduce foot-and-mouth disease, a devastating, contagious virus in cattle, helped open new worldwide markets.
"It was like the perfect storm for demand," said Walker. Responding to resulting increases in demand for beef, slaughterhouses proliferated throughout the Brazilian Amazon. These establishments acquire cattle from ranches, process the meat, and in some cases, export the produce directly to international consumers.
Today, Brazil is the world's biggest beef exporter, said Arima. While only 10 per cent of Brazil's beef exports were supplied by the Amazon in 2005, that figure doubled by 2006, and it is continuing to increase. Major markets for Brazilian beef currently include Latin America, the European Union, Russia, the Middle East and China. (The United States does not import Brazilian beef because it has its own large domestic cattle herds and because it prohibits the importation of beef from countries where foot-and-mouth disease has not been certified free in all sections, said Walker.)
Like the US's westward expansion
Cattle ranches will continue to replace forests in Brazil's Amazon as long as global demand for Brazilian beef and the profitability of cattle ranching persist. What's more, ongoing increases in global demand for soy and biofuels may convert former pastures to agriculture, pushing ranchers farther into the forest, explained Arima.
The population and cattle migration into the Brazilian Amazon resembles the westward expansion across the United States in the 19th century, "Brazil's Manifest Destiny," said Walker. The Brazilian government has promoted the development of the Amazon by sponsoring economic development programs, population relocation programs and the construction of dams, highways and a natural gas pipeline in the Brazilian Amazon.
Nevertheless, the Brazilian government is also heeding some of the lessons made apparent by America's destruction of its own forests. During the last 10 years, the Brazilian government has pursued aggressive policies on the designation of protected areas and on curbing encroachment in the Brazilian Amazon.
These policies have helped protect vast tracts of land that were previously up for grabs to whoever claimed them. In addition, enforcement of protections, particularly in indigenous reserves, has improved, said Arima.
Domestic and global forces will continue to drive both development and conservation in the Brazilian Amazon. It's now a question of how much of each will occur. "It's a two-edge sword in that there is this tremendous ecosystem that is largely intact but underneath that ecosystem and within it, there are riches that could be of great benefit to individuals and larger groups," explained Walker. "If you are in Brazil long enough you will see it both ways."
Splintered, charred wood litters the outskirts of an expansive ranch that lies on recently cleared land in the Brazilian Amazon. On the newly planted pasture, cattle leisurely graze, occasionally lifting their heads to gaze past heaps of dead trees towards an island of dense vegetation that has thus far been spared. But it too may soon be cut down.
Such scenes are becoming increasingly common as large swaths of the Brazilian Amazon are being bulldozed and burned to accommodate expanding cattle ranches. Deforestation, which is dismembering the Earth's functional heart and lungs, is largely resulting from cattle ranching driven by economic incentives and demand for Brazilian beef, according to the Centre for International Forestry Research.
"Probably 80 to 90 per cent of all cleared land in the region (the Brazilian Amazon) is attributable to some form of pasture or ranching," said Robert Walker, a geography professor at Michigan State University and an expert on land-use change in the Brazilian Amazon.
Deforestation is accelerating
Brazil has historically had the distinction of serving as the world's leader of deforestation. According to Walker, during the last three decades, an annual average of 6,500 square miles of the Brazilian Amazon, an area that is greater than the size of Connecticut, has been deforested.
Satellite data indicates that the rate of Amazonian deforestation is accelerating; in some areas, the rate increased by 50 per cent since last year. And, with over 20 million people and 70 million cattle now inhabiting the Amazon region, about a 600 per cent increase in the last 60 years, more trees are being razed to make room for cattle ranches, said Walker.
Small-scale ranchers, including poor, subsistence farmers, encroach on forests gradually, felling trees and creating modestly sized pastures in a piecemeal fashion. By contrast, larger land owners use tractors and bulldozers to quickly mow down vast tracts of forest, and then burn remaining vegetation to establish huge ranches. Either way, the landscape ends up fragmented and ecologically devastated.
Ground zero for global extinction
As the world's largest tropical rainforest, the Amazon houses the world's largest collection of living species of plants and animals. It also plays a significant role in stabilising local climate and may provide the raw materials for cures for some of the world's deadliest diseases.
But deforestation has transformed the Amazon into ground zero for global extinction. In addition, burning and rotting trees release carbon dioxide, which contributes greatly to climate change.
"Brazil overall is the fifth or sixth largest emitter of carbon dioxide and, by far, the most important source is deforestation," said Eugenio Arima, an assistant professor of environmental studies at Hobart and William Smith Colleges and a former conservation and development researcher at the Brazilian non-profit institute Imazon.
The cattle economy
With support from the National Science Foundation, Walker and Arima are currently researching Brazil's dynamic cattle economy; their research is exposing links between globalisation and deforestation.
According to Walker and Arima's research, reduced transportation costs from the construction of highways in the Amazon, together with the rise in beef prices, provided economic incentives to increase cattle grazing in the region. In addition, the devaluation of the Brazilian real decreased the costs of importing beef from Brazil, and efforts to reduce foot-and-mouth disease, a devastating, contagious virus in cattle, helped open new worldwide markets.
"It was like the perfect storm for demand," said Walker. Responding to resulting increases in demand for beef, slaughterhouses proliferated throughout the Brazilian Amazon. These establishments acquire cattle from ranches, process the meat, and in some cases, export the produce directly to international consumers.
Today, Brazil is the world's biggest beef exporter, said Arima. While only 10 per cent of Brazil's beef exports were supplied by the Amazon in 2005, that figure doubled by 2006, and it is continuing to increase. Major markets for Brazilian beef currently include Latin America, the European Union, Russia, the Middle East and China. (The United States does not import Brazilian beef because it has its own large domestic cattle herds and because it prohibits the importation of beef from countries where foot-and-mouth disease has not been certified free in all sections, said Walker.)
Like the US's westward expansion
Cattle ranches will continue to replace forests in Brazil's Amazon as long as global demand for Brazilian beef and the profitability of cattle ranching persist. What's more, ongoing increases in global demand for soy and biofuels may convert former pastures to agriculture, pushing ranchers farther into the forest, explained Arima.
The population and cattle migration into the Brazilian Amazon resembles the westward expansion across the United States in the 19th century, "Brazil's Manifest Destiny," said Walker. The Brazilian government has promoted the development of the Amazon by sponsoring economic development programs, population relocation programs and the construction of dams, highways and a natural gas pipeline in the Brazilian Amazon.
Nevertheless, the Brazilian government is also heeding some of the lessons made apparent by America's destruction of its own forests. During the last 10 years, the Brazilian government has pursued aggressive policies on the designation of protected areas and on curbing encroachment in the Brazilian Amazon.
These policies have helped protect vast tracts of land that were previously up for grabs to whoever claimed them. In addition, enforcement of protections, particularly in indigenous reserves, has improved, said Arima.
Domestic and global forces will continue to drive both development and conservation in the Brazilian Amazon. It's now a question of how much of each will occur. "It's a two-edge sword in that there is this tremendous ecosystem that is largely intact but underneath that ecosystem and within it, there are riches that could be of great benefit to individuals and larger groups," explained Walker. "If you are in Brazil long enough you will see it both ways."
World's Biggest Snake Gives Climate Clues
Skeletal remains from an enormous snake that would dwarf Hollywood's anacondas have been discovered near the equator, shedding new light on the climate and environment that housed the monstrous reptile 60 million years ago
Skeletal remains from an enormous snake that would dwarf Hollywood's anacondas have been discovered near the equator, shedding new light on the climate and environment that housed the monstrous reptile 60 million years ago.
"This colossal, boa constrictor-like creature stretched longer than a city bus and weighed more than a car. It's the biggest snake the world has ever known," says University of Toronto Mississauga palaeontologist Jason Head, part of an international team that analysed the remains. Their findings are published in the February 5, 2009 edition of Nature.
The snake's giant vertebrate, found in Colombia, show it was far larger than any previously discovered, says Head, lead author on the paper. The giant reptile weighed more than 1.25 tons, was more than 13 metres long and had a body so wide it would have to squeeze through a doorway to enter a room. The snake ate giant turtles and crocodiles, whose skeletons were also uncovered.
Jonathan Bloch, a vertebrate palaeontologist at the University of Florida's Florida Museum of Natural History, who co-led the expedition that discovered the snake with Carlos Jaramillo from the Smithsonian Tropical Research Institute, says the find provides scientists with a rare window into past equatorial environment.
"Until now, tropical South America's dense forest prevented discovery of fossil vertebrates found between 55 and 65 million years ago, so this discovery gives us a very unique and important glimpse into the past," he says.
Since the body size of snakes and other cold-blooded animals is determined by the temperature where they live, researchers used the snake's huge dimensions to paint a picture of what the equatorial climate was like 60 million years ago. Based on its size, scientists found the mean annual temperature at equatorial South America during that time would have been nearly 33 Celsius, about six degrees warmer than today.
"The key thing about this discovery is that we can use it as a launching point to develop very precise climatic reconstructions," says Head. "It will help us to look at how ecosystems respond to climate change and specifically, what happens when temperatures increase or decrease. Obviously, this type of knowledge is very relevant in today's changing climate."
Skeletal remains from an enormous snake that would dwarf Hollywood's anacondas have been discovered near the equator, shedding new light on the climate and environment that housed the monstrous reptile 60 million years ago.
"This colossal, boa constrictor-like creature stretched longer than a city bus and weighed more than a car. It's the biggest snake the world has ever known," says University of Toronto Mississauga palaeontologist Jason Head, part of an international team that analysed the remains. Their findings are published in the February 5, 2009 edition of Nature.
The snake's giant vertebrate, found in Colombia, show it was far larger than any previously discovered, says Head, lead author on the paper. The giant reptile weighed more than 1.25 tons, was more than 13 metres long and had a body so wide it would have to squeeze through a doorway to enter a room. The snake ate giant turtles and crocodiles, whose skeletons were also uncovered.
Jonathan Bloch, a vertebrate palaeontologist at the University of Florida's Florida Museum of Natural History, who co-led the expedition that discovered the snake with Carlos Jaramillo from the Smithsonian Tropical Research Institute, says the find provides scientists with a rare window into past equatorial environment.
"Until now, tropical South America's dense forest prevented discovery of fossil vertebrates found between 55 and 65 million years ago, so this discovery gives us a very unique and important glimpse into the past," he says.
Since the body size of snakes and other cold-blooded animals is determined by the temperature where they live, researchers used the snake's huge dimensions to paint a picture of what the equatorial climate was like 60 million years ago. Based on its size, scientists found the mean annual temperature at equatorial South America during that time would have been nearly 33 Celsius, about six degrees warmer than today.
"The key thing about this discovery is that we can use it as a launching point to develop very precise climatic reconstructions," says Head. "It will help us to look at how ecosystems respond to climate change and specifically, what happens when temperatures increase or decrease. Obviously, this type of knowledge is very relevant in today's changing climate."
What We Don’t Know Still Hurts Us
Knowledge gaps continue to hobble scientists’ assessments of the environment, a Michigan State University researcher and colleagues warn. Their warning follows sobering conclusions drawn from what they do know and could help set the global agenda for research funding in the years to come.
A worldwide 2005 Millennium Ecosystem Assessment enlisted hundreds of scientists to develop a view of ecosystems through the lens of services those ecosystems provide humanity, said Thomas Dietz, director of the MSU Environmental Science and Policy Program and professor in sociology and crop and soil sciences. The MEA found about 60 percent of ecosystem services supporting life — including fresh water, fisheries, clean air, pests and climate — are being degraded or used unsustainably. The MEA projected continued deterioration at current rates.
But drawing conclusions is still limited by what researchers call discipline-bound approaches that don’t fully describe the range of the Earth’s dynamic and complex biophysical and social systems.
“In only a few cases are the abilities of ecosystems to provide human well-being holding steady, and in almost every case we’re seeing declines in ecosystems underpinning human well-being,” said Dietz, who was involved in the original MEA.
Many view that assessment as a baseline for analyzing climate change, Dietz said, although that was not the purpose of the report. He and fellow scientists are set to publish what amounts to a post-MEA gap analysis in the Proceedings of the National Academy of Science.
“The conclusion that things are getting worse in general comes out of the Millennium Ecosystem Assessment,” he said. “Our job was to say ‘OK, what science do we need to do?’”
Among the biggest knowledge gaps Dietz and colleagues found, he said, is “really thinking seriously about the interaction between humans and ecosystems, back and forth. How are we changing ecosystems and how are ecosystems affecting us?”
Probing such questions suggests a larger role for MSU, Dietz said, given its strengths in researching coupled human and natural systems.
The lack of long-term ecosystem monitoring and data collection is another deficiency the world scientific and policy communities must address, Dietz and colleagues wrote. Research tends to be underwritten for maybe three years, but data needs, in many cases, to span decades to be of greatest value.
On the other end of the spectrum, addressing abrupt ecosystem changes — “those are the scary things” — and developing early warning systems also are challenges confronting scientists and the policymakers.
Recommendations such as those made by Dietz’s group tend to carry weight when national science agencies make research funding decisions, he said. Ecosystem change might sound like an academic subject to many in the developed world, he said, but “for an awful lot of people around the world, the functioning of the ecosystem is right in their front yard and at their water tap.”
Dietz is vice-chairperson of the Panel on Advancing the Science of Climate Change for the National Academies’ “America’s Climate Choices” study commissioned by the U.S. Congress. He published his paper with collaborators Stephen R. Carpenter, Harold A. Mooney, John Agard, Doris Capistrano, Ruth S. DeFries, Sandra Díaz, Anantha K. Duraiappah, Alfred Oteng-Yeboah, Henrique Miguel Pereira, Charles Perrings, Walter V. Reid, Jose´ Sarukhan, Robert J. Scholes and Anne Whyte.
A worldwide 2005 Millennium Ecosystem Assessment enlisted hundreds of scientists to develop a view of ecosystems through the lens of services those ecosystems provide humanity, said Thomas Dietz, director of the MSU Environmental Science and Policy Program and professor in sociology and crop and soil sciences. The MEA found about 60 percent of ecosystem services supporting life — including fresh water, fisheries, clean air, pests and climate — are being degraded or used unsustainably. The MEA projected continued deterioration at current rates.
But drawing conclusions is still limited by what researchers call discipline-bound approaches that don’t fully describe the range of the Earth’s dynamic and complex biophysical and social systems.
“In only a few cases are the abilities of ecosystems to provide human well-being holding steady, and in almost every case we’re seeing declines in ecosystems underpinning human well-being,” said Dietz, who was involved in the original MEA.
Many view that assessment as a baseline for analyzing climate change, Dietz said, although that was not the purpose of the report. He and fellow scientists are set to publish what amounts to a post-MEA gap analysis in the Proceedings of the National Academy of Science.
“The conclusion that things are getting worse in general comes out of the Millennium Ecosystem Assessment,” he said. “Our job was to say ‘OK, what science do we need to do?’”
Among the biggest knowledge gaps Dietz and colleagues found, he said, is “really thinking seriously about the interaction between humans and ecosystems, back and forth. How are we changing ecosystems and how are ecosystems affecting us?”
Probing such questions suggests a larger role for MSU, Dietz said, given its strengths in researching coupled human and natural systems.
The lack of long-term ecosystem monitoring and data collection is another deficiency the world scientific and policy communities must address, Dietz and colleagues wrote. Research tends to be underwritten for maybe three years, but data needs, in many cases, to span decades to be of greatest value.
On the other end of the spectrum, addressing abrupt ecosystem changes — “those are the scary things” — and developing early warning systems also are challenges confronting scientists and the policymakers.
Recommendations such as those made by Dietz’s group tend to carry weight when national science agencies make research funding decisions, he said. Ecosystem change might sound like an academic subject to many in the developed world, he said, but “for an awful lot of people around the world, the functioning of the ecosystem is right in their front yard and at their water tap.”
Dietz is vice-chairperson of the Panel on Advancing the Science of Climate Change for the National Academies’ “America’s Climate Choices” study commissioned by the U.S. Congress. He published his paper with collaborators Stephen R. Carpenter, Harold A. Mooney, John Agard, Doris Capistrano, Ruth S. DeFries, Sandra Díaz, Anantha K. Duraiappah, Alfred Oteng-Yeboah, Henrique Miguel Pereira, Charles Perrings, Walter V. Reid, Jose´ Sarukhan, Robert J. Scholes and Anne Whyte.
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