More than 75% of the world's tropical forests went through drought and heat more extreme than usual during the El Nino years of 2023 and 2024, according to a study in Earth's Future reported by Down To Earth. Over three quarters of the forests endured an average of six months of anomalous drought and heat.
The researchers used several climate data sets from 2000 to 2024 covering 15.9 million square km of forest: 8.4 million in the Americas, 3.6 million in Africa and 3.9 million in Asia, and projected conditions to 2100. Compound hot and dry events hit on average 88% of American and 89% of African tropical forest area, against 43% in Asia, and lasted up to four times longer than in the 2015-16 El Nino. Heatwaves ran for 17 to 19 of the 24 months on all three continents.
Drier than usual conditions affected 80% of pantropical forests, including 91% in the Americas, 92% in Africa and 48% in Asia; Asia was the one region where the drought-hit area was smaller than in 2015-16, by 22%. About 80% of the anomalously dry and hot months fell in the wet season, which the authors say disrupts the groundwater recharge trees need to survive the following dry months.
Burned area rose by 9% and reports of forest degradation by 19% during the 2023-24 event, which the study reads as an accelerating drought, fire and degradation cycle. Drought resilience has fallen in Southeast Asia and West Africa, so even milder droughts may now turn carbon sinks into degraded land.
Under probable emission scenarios, the authors warn, the heat of 2023-24 could become normal for tropical forests in under 20 years; under high emissions, record-level annual temperatures become an every-year event by as early as 2043, and drought in the Amazon, Central America and Southern Africa becomes up to nine times more likely by 2100. Tropical forests absorb about 1.2 Pg of carbon a year, and widespread tree death would harm the water and carbon cycles and the livelihoods of millions. The report is by Himanshu Nitnaware.
Photo: NASA Earth Observatory / Wanmei Liang / Wikimedia Commons (Public domain)
Source: Down To Earth
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