Many plant and animal species are unlikely to survive climate change. Using projections of species' distributions for future climate scenarios, the report assesses extinction risks for sample regions that cover some 20 per cent of the Earth's terrestrial surface. It looks at three approaches in which the estimated probability of extinction shows a power-law relationship with geographical range size. It predicts that, on the basis of mid-range climate-warming scenarios for 2050, that 15–37 per cent of species in their sample of regions and taxa (sample size 1,103 land plants and animals) will be committed to extinction.When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction (18 per cent) than mid-range (24 per cent) and maximum-change (35 per cent) scenarios. These estimates show the importance of rapid implementation of technologies to decrease greenhouse gas emissions and strategies for carbon sequestration. A rapid shift to technologies that do not produce greenhouse gases, combined with carbon sequestration, could save 15–20 per cent of species from extinction.