https://www.eurekalert.org/pub_releases/2020-12/uol-ctf121120.php
News Release 14-Dec-2020
University of Leeds
For the first time scientists have provided clear evidence that tropical tree lifespan decreases above a critical temperature threshold.
Findings, published today (14 December) in the journal PNAS (Proceedings of the National Academy of Sciences) show that across the tropics, tree lifespans decrease for temperatures above 25 C [77 F].
As temperatures are rising rapidly across large parts of the tropics, tree mortality is likely to accelerate in substantial parts of the tropics, including the Amazon, Pantanal and Atlantic forests with implications for animal habitats, air quality and carbon stocks.
Although tropical rainforests account for only 7% of all land, they are home to about 50% of all animal and plant species, and approximately 50 % of forest carbon stocks on earth. Thus small changes in the functioning of tropical forests can significantly change the atmospheric levels of CO2 - the most important anthropogenic greenhouse gas.
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Currently, average temperatures in tropical rainforests vary between 21 C [70 F] and 30 C [86 F] . According to the latest forecasts, tropical temperatures on land will continue to rise, reaching on average a combined 2.5 C [4.5 F] above pre-industrial levels over the next 10 to 20 years. The study also shows that temperature effects on tree longevity will be further exacerbated by dry conditions.
Climate change will also have an impact on tropical rainforests outside of South America, such as the Congo Forest in west Africa - the second largest tropical forest in the world after the Amazon.
Dr Locosselli added: "While tropical rainforests in the Amazon are already close to this temperature threshold temperatures in the Congo are lower. But, with this great increase in temperature, we might begin to see signs of increased tree mortality. From this point of view, the scenario is quite bleak."
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