Climate change already affects species in diverse, mostly negative, ways
Climate change is not just a concern for the future: It is already threatening species. Climate change has been an important driver of bird population trends across northern continents since the 1980s. So far, one-quarter of species studied in detail show negative responses to recent climate change, while only one in eight responded positively.
Recent bird population trends in Europe show a strong signal of climate change
Warm-adapted species (those whose distributions are projected to expand under climate change) have increased in abundance in Europe over recent decades, while cool-adapted species (those whose distributions are projected to contract) have decreased in abundance. The ratio of the trends for the two sets of species—the Climatic Impact Index—shows a strong signal of climate change on bird populations since about 1990, with the increasing trend showing that the overall impact of climate change on bird populations is growing. Recent results for North America are similar.
More species have responded negatively than positively to recent climate change
A recent review of the scientific literature shows that 24% of the 570 bird species studied in detail around the world have been negatively affected by climate change to date, while only 13% have responded positively. For half of all species, the impact remains uncertain. Most negative impacts to date relate to reductions in abudance and range size.