It is a tough time to be a tree. Earth has lost a third of its forests over the past 10,000 years—half of that just since 1900. We logged them for wood. We cut them to make way for farms and cattle. We cleared land to build homes and roads. Although deforestation has decreased globally from its peak in the 1980s, trends vary by region. In Indonesia, which had been cutting down forests for oil palm plantations(棕榈种植园), primary forest loss has declined since 2016. From August 2020 to July 2021, the Brazilian Amazon lost 5,000 square miles of rainforest, a 22 percent increase over the previous year. Since 1990, we've cut down more forest globally than there is forest in the United States.
Trees are growing faster as they absorb extra CO2. That "greening" of the planet has so far helped slow climate change. But climate change is killing trees. And what has made forest scientists increasingly uneasy is the quickening pace of extreme events—fire, more powerful storms, and, most notably, severe heat and drought, which can worsen the effects of all the rest, shifting forests that have been around since the last ice age to entirely new states.
Climate change still poses less of a threat to forests than logging and land clearing, but the threat is growing fast. Satellite data show that Earth's tree-covered area actually expanded from 1982 to 2016 by 7 percent, an area larger than Mexico. But that doesn't mean forests are doing fine. The data don't distinguish between natural forests and industrial tree farms, such as the millions of palm, eucalyptus(桉树), and pine trees planted as crops while rainforest is cleared. Also, the data don't show which forests were lost to chain saws and which were killed by climate-related events.
