"How climate-change-driven drying of the air is leading to tree deaths the world over"
"When scientist Craig Allen first arrived in the Jemez Mountains of northern New Mexico in the early 1980s, the American Southwest was in the early years of a decades-long wet period. It was, in Allen’s words, a “good time to be a tree.” Allen had gone to New Mexico to study the local forests for the US Geological Survey. Fast forward two decades and conditions have radically changed.
Starting in the late 1990s and early 2000s, the Southwest’s long-term climate pivoted sharply, transitioning to what scientists are now calling a “megadrought.” The drought was marked by a decline in precipitation. But it also included something new: abnormally warm temperatures. The combination would prove deadly. The early 2000s marked the start of a region-wide, massive die-off of trees that continues to this day.
“2002 was the real kick in the teeth in terms of forest dieback here,” says Allen, now an adjunct professor at the University of New Mexico in Albuquerque. “There were millions of acres of different species of trees dying across the whole region.”
What makes the Southwest’s current megadrought so exceptional and so very different from the region’s notorious megadroughts of the past, says Allen, isn’t so much a lack of precipitation as an excessive amount of heat. Scientists have determined that about a third of the strength of the current megadrought is due not to a lack of water but to warming tied to climate change. Heat, it is now known, is making the region’s drought worse. But elsewhere heat is also leading to a very new and worrying development: drought-induced tree die-offs in regions not typically known for droughts."
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