A chronic state of incomplete drought recovery may be the new normal for the remainder of the 21st century, thanks to increasingly common extreme temperatures, new research suggests.
The findings, published in the journal Nature, showed that land ecosystems took progressively longer to recover from droughts in the 20th century.
"Using the vantage point of space, we can see all of Earth's forests and other ecosystems getting hit repeatedly and increasingly by droughts," said study co-author Josh Fisher of NASA's Jet Propulsion Laboratory at Pasadena.
The research team, led by Christopher Schwalm of Woods Hole Research Center, Falmouth, Massachusetts, measured recovery time following droughts in various regions of the world.
They used projections from climate models verified by observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite and ground measurements.
The researchers found that drought recovery was taking longer in all land areas. In two particularly vulnerable regions -- the tropics and northern high latitudes -- recovery took even longer than in other regions.
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"Some of these ecosystems recover, but, with increasing frequency, others do not. Data from our 'eyes' in space allow us to verify our simulations of past and current climate, which, in turn, helps us reduce uncertainties in projections of future climate," Fisher said.
The conditions most-strongly contributing to drought recovery time were precipitation and temperature, the scientists found.
Recovery time is a crucial metric for assessing the resilience of ecosystems, shaping the odds of crossing a tipping point after which trees begin to die, according to the scientists.
"If another drought arrives before trees and other plants have recovered from the last one, the ecosystem can reach a 'tipping point' where the plants' ability to function normally is permanently affected," said Yuanyuan Fang of Carnegie Institution for Science, Stanford, California.
Shorter times between droughts, combined with longer drought recovery times, may lead to widespread tree death, decreasing the ability of land areas to absorb atmospheric carbon.
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