As temperatures rise because of climate change, trees are being hit with heat waves and drought, killing them or weakening their resistance to a cascade of pressures, from pests to rising sea levels.
The majority of Earth's biodiversity on land can be found in forests. Yet only 18 percent of these tracts are in legally protected areas such as national parks. In the past two decades alone, large intact forest around the world shrank by 12 percent.
More than 450 non-native insects and diseases have found their way into U.S. forests, and the millions of trees killed by these pests each year contain carbon equal to the emissions of 4.4 million cars.
