Editor’s choice
The 2015–2016 El Niño event caused record heat and drought across South America and presented a unique opportunity to evaluate both the impact of long-term climate baselines and short-term climate anomalies on South American forests. In this article, the authors assessed it’s impact on South American tropical forests using 123 long-term monitoring plots in the RAINFOR and PPBio networks, the largest on-the-ground dataset yet mobilized to address the impact of a single tropical drought.
The single-lane wooden bridge of the RR-203 state highway spans the Paiva river, which has nearly dried up in the drought of the 2016 "El Niño" climate. The river is usually much larger, and a dramatic reminder of the severest droughts that the state of Roraima in northern Brazil has been enduring in decades.
The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here the authors report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha−1 per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected.
Perspective / Research from SEI and ACTO shows how a new declaration can be strengthened to protect this tropical rainforest, in South America and beyond.
Past event / This session in this year's Gobeshona Global Conference will detail SEI's research on how to tailor Loss and Damage financial support to local needs.
Feature / COP27 ended with a decision to establish a Loss and Damage fund for countries most-affected by climate change. SEI and ICCCAD researchers want your insight.
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