The current Earth system models used for climate predictions show that the Amazon rainforest is very sensitive to water stress. Since the air in the future is predicted to get warmer and drier with climate change, translating to increased water stress, this could have large implications not just for the forest’s survival, but also for its storage of CO2. If the forest is not able to survive in its current capacity, climate change could greatly accelerate.
Columbia Engineering researchers decided to investigate whether this was true, whether these forests are really as sensitive to water stress as what the models have been showing. In a study published in Science Advances, they report their discovery that these models have been largely over-estimating water stress in tropical forests.
The team found that, while models show that increases in air dryness greatly diminish photosynthesis rates in certain regions of the Amazon rainforest, the observational data results show the opposite: in certain very wet regions, the forests instead even increase photosynthesis rates in response to drier air…[In fact] As the trees become stressed, they generate more efficient leaves that can more than compensate for water stress.”…
“So much of the scientific research coming out these days is that with climate change, our current ecosystems might not be able to survive, potentially leading to the acceleration of global warming due to feedbacks,” Gentine added. “It was nice to see that maybe some of our estimates of approaching mortality in the Amazon rainforest may not be quite as dire as we previously thought.”
Excerpts from Some Amazon Rainforest Regions More Resistant to Climate Change than Previously Thought, Columbia Engineering, Nov. 20, 2020