Compensatory water effects link yearly global land CO₂ sink changes to temperature

Area of Science:

• Earth System Science
• Ecology
• Climate Science

Background:

• Interannual variations in atmospheric CO2 growth rates are mainly driven by land ecosystem carbon uptake.
• The precise roles of temperature and water availability in controlling land ecosystem carbon balance remain unclear across scales.

Purpose of the Study:

• To investigate the influence of temperature and water availability on gross primary productivity (GPP), terrestrial ecosystem respiration (TER), and net ecosystem exchange (NEE).
• To differentiate the impacts of climate variables on local and global carbon balance variability.

Main Methods:

• Utilized empirical models based on eddy covariance data.
• Employed process-based models to simulate ecosystem responses.
• Analyzed data at both local and global scales.

Main Results:

• Water availability was the primary driver of local interannual variability in GPP and TER.
• Temperature fluctuations were the main driver of global NEE variability.
• Compensatory effects of water availability at local and spatial scales reconciled the differing influences of water and temperature.

Conclusions:

• Spatial climate covariation, particularly temperature, significantly influences the global carbon cycle response.
• Reconciled conflicting reports on the relative importance of temperature and water in regulating terrestrial carbon balance variability.
• Emphasized the complex interplay between water and temperature in modulating ecosystem carbon dynamics.