Plant Physiology Increases the Magnitude and Spread of the Transient Climate Response to CO₂ in CMIP6 Earth System Models

• Autor: Zarakas, Claire M. ; Swann, Abigail L. S. ; Laguë, Marysa M. ; Armour, Kyle C. ; Randerson, James T.
• Assuntos: Air temperature ; Atmosphere-land interaction ; Atmospheric models ; Biosphere-atmosphere interaction ; Carbon cycle ; Carbon dioxide ; Carbon dioxide atmospheric concentrations ; Carbon dioxide concentration ; Climate ; Climate change ; Climate models ; Climate sensitivity ; Conductance ; Earth ; ENVIRONMENTAL SCIENCES ; Evapotranspiration ; Fluxes ; Greenhouse effect ; Greenhouse gases ; Intercomparison ; Leaf area ; Meteorology & Atmospheric Sciences ; Physiological effects ; Physiological responses ; Physiology ; Plant cover ; Plant physiology ; Resistance ; Stomata ; Stomatal conductance ; Surface energy ; Surface properties ; Surface-air temperature relationships ; Water use
• É parte de: Journal of climate, 2020-10, Vol.33 (19), p.8561-8578
• Notas: National Science Foundation (NSF)
  SC0020347; AGS-1553715; AGS-1752796
  USDOE Office of Science (SC), Biological and Environmental Research (BER)
  
• Descrição: Increasing concentrations of CO₂ in the atmosphere influence climate both through CO₂’s role as a green-house gas and through its impact on plants. Plants respond to atmospheric CO₂ concentrations in several ways that can alter surface energy and water fluxes and thus surface climate, including changes in stomatal conductance, water use, and canopy leaf area. These plant physiological responses are already embedded in most Earth system models, and a robust literature demonstrates that they can affect global-scale temperature. However, the physiological contribution to transient warming has yet to be assessed systematically in Earth system models. Here this gap is addressed using carbon cycle simulations from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP) to isolate the radiative and physiological contributions to the transient climate response (TCR), which is defined as the change in globally averaged near-surface air temperature during the 20-yr window centered on the time of CO₂ doubling relative to preindustrial CO₂ concentrations. In CMIP6 models, the physiological effect contributes 0.12°C (σ: 0.09°C; range: 0.02°–0.29°C) of warming to the TCR, corresponding to 6.1% of the full TCR (σ: 3.8%; range: 1.4%–13.9%). Moreover, variation in the physiological contribution to the TCR across models contributes disproportionately more to the intermodel spread of TCR estimates than it does to the mean. The largest contribution of plant physiology to CO₂-forced warming—and the intermodel spread in warming—occurs over land, especially in forested regions.
  
• Editor: Boston: American Meteorological Society
  
• Idioma: Inglês