Increasing global temperatures are expected to harm ecosystems, pushing extinction to those species that cannot adapt. The first comprehensive assessment of the extinction risk from global warming found that more than 1 million species could be extinct by 2050 if the current rate continues. A recent study of nearly 2,000 species of plants and animals discovered movement toward the poles at an average rate of 3.8 miles per decade. The latest climate change report found that approximately 20 to 30 percent of plant and animal species assessed so far are likely to be at increased risk of extinction if global average temperature increases by more than 2.7 to 4.5 degrees Fahrenheit. Some polar bears are drowning because they have to swim longer distances to reach ice floes. The U. S. Geological Survey has predicted that two-thirds of the world's polar bear populations will be extinct by the mid-century due to melting of the Arctic ice cap. The ocean will continue to become more acidic due to carbon dioxide emissions. Because of this acidification, species with hard calcium carbonate shells are vulnerable, as are coral reefs, which are vital to ocean ecosystems. Scientists predict that a 3.6 degree Fahrenheit increase in temperature would wipe out 97 percent of the world's coral reefs. Tìm cho mình 25 từ khó trở lên và cho biết nghĩa và từ loại nhé. (n,v,adj,adv)