Next week, the world's governments are meeting at the United Nation's Climate Change Conference in Copenhagen, Denmark to attempt to agree action to tackle climate change. The outcomes of this will have resounding consequences for biodiversity.Climate change is already having multiple impacts on birds and their habitats, and is exacerbating many of the factors which have put one in eight of the world's birds at risk of extinction. Many species may have to shift their ranges to survive, and considerably more losers than winners are expected.
One global study estimates that 15–37 per cent of species could be committed to extinction by 2050 as a consequence of climate change; another that each degree of warming could drive another 100-500 bird species extinct. Temperature rises beyond 2°C are predicted to lead to catastrophic effects on birds, nature, people and the global economy.
Climate change is impacting birds in several ways:
- range shifts and contractions (poleward in latitude and upward in altitude)
- population declines
- changes in behaviour and phenology such as the timing of egg-laying, breeding, and emergence of insects as food source
- disruption of species interactions (predators and prey) and communities
- exacerbation of other threats and stresses, such as disease, invasive species, and habitat fragmentation, destruction and degradation
- increased extreme weather events
- loss of coastal habitats including feeding areas for shorebirds and nesting sites for seabirds, or entire island ecosystems, due to sea-level rise
- ocean warming effecting ocean productivity, bringing knock-on effects further up the food change
"The BirdLife Partnership is involved in several ground-breaking studies monitoring the impacts of climate change on birds", said Melanie Heath, BirdLife's Senior Advisor on Climate Change.
"For example, analyses of citizen-gathered data from the past 40 years by Audubon (BirdLife in the USA) revealed that 58 per cent of the 305 widespread species that winter on the continent have shifted significantly north since 1968, some by hundreds of kilometres."
In this study, movement was detected among species of every type, including more than 70 per cent of highly adaptable forest birds. Only 38 per cent of grassland species exhibited movement however, reflecting the constraints of their severely-depleted habitat and suggesting that they now face a combined threat of the loss of habitat and climate space. Audubon scientists say the ongoing trend of movement by some 177 species - closely correlated to long-term winter temperature increases - reveals an undeniable link to the changing climate.
Another important project that BirdLife has been involved in is A Climatic Atlas of European Breeding Birds. Described as a 'landmark' in our understanding of how climate change will affect wildlife, the atlas uses 'climate envelope modelling', and predicts that without vigorous and immediate action against climate change, the potential future distribution of the average European bird species will shift by nearly 550 km north-east by the end of this century, reduce in size by a fifth, and overlap the current range by only 40 per cent.
Three quarters of all Europe's nesting bird species are likely to suffer declines in range. Arctic and sub-Arctic birds, and some Iberian species, are projected to suffer the greatest potential range loss. Projected changes for some species found only in Europe or with only small populations elsewhere, suggest that climate change could set some on a path to extinction.
By 2100, sea-level rise could be between 0.5 and 1.4m, irreversibly altering small islands, reefs, atolls and, in turn, the low-lying coastal and intertidal habitats of many shore-nesting birds such as terns. A disproportionately high number of threatened birds occur on islands. Research in the North-western Hawaiian Islands suggests that sea-level rise could cause the loss of a significant proportion of the nesting sites for the Vulnerable Laysan Phoebastria immutabilis and Endangered Black-footed Albatross P. nigripes, and of the most populous remaining breeding sites for the Near Threatened Tristram’s Storm-petrel Oceanodroma tristrami. Similar sea-level rise scenarios applied throughout the Pacific would virtually eliminate the Endangered Phoenix Petrel Pterodroma alba and Vulnerable White-throated Storm-petrel Nesofregetta fuliginosa.
BirdLife’s data shows that over 400 bird species have already had documented climate-driven impacts to date. Given that the actual rise in global average temperature to date has been relatively modest, this is sobering. It suggests that the impact of future climate change on biological communities, and consequently ecosystem integrity, will be severe unless global emissions are cut by the amount needed to limit global average temperature rises to well below 2°C above pre-industrial levels. The world’s leaders need to act now and reach agreement on a fair, ambitious and binding deal in Copenhagen.
