TY - JOUR
T1 - Tropical forests are approaching critical temperature thresholds
AU - Doughty, Christopher E.
AU - Keany, Jenna M.
AU - Wiebe, Benjamin C.
AU - Rey-Sanchez, Camilo
AU - Carter, Kelsey R.
AU - Middleby, Kali B.
AU - Cheesman, Alexander W.
AU - Goulden, Michael L.
AU - da Rocha, Humberto R.
AU - Miller, Scott D.
AU - Malhi, Yadvinder
AU - Fauset, Sophie
AU - Gloor, Emanuel
AU - Slot, Martijn
AU - Oliveras Menor, Imma
AU - Crous, Kristine Y.
AU - Goldsmith, Gregory R.
AU - Fisher, Joshua B.
N1 - Publisher Copyright:
© 2023, The Author(s), under exclusive licence to Springer Nature Limited.
PY - 2023/9/7
Y1 - 2023/9/7
N2 - The critical temperature beyond which photosynthetic machinery in tropical trees begins to fail averages approximately 46.7 °C (T crit)1. However, it remains unclear whether leaf temperatures experienced by tropical vegetation approach this threshold or soon will under climate change. Here we found that pantropical canopy temperatures independently triangulated from individual leaf thermocouples, pyrgeometers and remote sensing (ECOSTRESS) have midday peak temperatures of approximately 34 °C during dry periods, with a long high-temperature tail that can exceed 40 °C. Leaf thermocouple data from multiple sites across the tropics suggest that even within pixels of moderate temperatures, upper canopy leaves exceed T crit 0.01% of the time. Furthermore, upper canopy leaf warming experiments (+2, 3 and 4 °C in Brazil, Puerto Rico and Australia, respectively) increased leaf temperatures non-linearly, with peak leaf temperatures exceeding T crit 1.3% of the time (11% for more than 43.5 °C, and 0.3% for more than 49.9 °C). Using an empirical model incorporating these dynamics (validated with warming experiment data), we found that tropical forests can withstand up to a 3.9 ± 0.5 °C increase in air temperatures before a potential tipping point in metabolic function, but remaining uncertainty in the plasticity and range of T crit in tropical trees and the effect of leaf death on tree death could drastically change this prediction. The 4.0 °C estimate is within the ‘worst-case scenario’ (representative concentration pathway (RCP) 8.5) of climate change predictions2 for tropical forests and therefore it is still within our power to decide (for example, by not taking the RCP 6.0 or 8.5 route) the fate of these critical realms of carbon, water and biodiversity3,4.
AB - The critical temperature beyond which photosynthetic machinery in tropical trees begins to fail averages approximately 46.7 °C (T crit)1. However, it remains unclear whether leaf temperatures experienced by tropical vegetation approach this threshold or soon will under climate change. Here we found that pantropical canopy temperatures independently triangulated from individual leaf thermocouples, pyrgeometers and remote sensing (ECOSTRESS) have midday peak temperatures of approximately 34 °C during dry periods, with a long high-temperature tail that can exceed 40 °C. Leaf thermocouple data from multiple sites across the tropics suggest that even within pixels of moderate temperatures, upper canopy leaves exceed T crit 0.01% of the time. Furthermore, upper canopy leaf warming experiments (+2, 3 and 4 °C in Brazil, Puerto Rico and Australia, respectively) increased leaf temperatures non-linearly, with peak leaf temperatures exceeding T crit 1.3% of the time (11% for more than 43.5 °C, and 0.3% for more than 49.9 °C). Using an empirical model incorporating these dynamics (validated with warming experiment data), we found that tropical forests can withstand up to a 3.9 ± 0.5 °C increase in air temperatures before a potential tipping point in metabolic function, but remaining uncertainty in the plasticity and range of T crit in tropical trees and the effect of leaf death on tree death could drastically change this prediction. The 4.0 °C estimate is within the ‘worst-case scenario’ (representative concentration pathway (RCP) 8.5) of climate change predictions2 for tropical forests and therefore it is still within our power to decide (for example, by not taking the RCP 6.0 or 8.5 route) the fate of these critical realms of carbon, water and biodiversity3,4.
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U2 - 10.1038/s41586-023-06391-z
DO - 10.1038/s41586-023-06391-z
M3 - Article
C2 - 37612501
AN - SCOPUS:85168599598
SN - 0028-0836
VL - 621
SP - 105
EP - 111
JO - Nature
JF - Nature
IS - 7977
ER -