Investigating Variability in the Intensity, Direction, and Spatial Distribution of Carbon Cycle Extremes and Attribution to Climate Drivers Using Observations and CMIP6 Earth System Models.
Abstract
Terrestrial ecosystems and their biodiversity are significantly affected by climate-driven carbon cycle (e.g. gross primary productivity, GPP) extreme events, and the impact of compound climate drivers on carbon cycle extremes is expected to increase under future climate change. While terrestrial ecosystems have sequestered a quarter of the anthropogenic carbon emissions over the last decade, the variability in the magnitude, spatial and temporal distribution of carbon cycle anomalies and their climate drivers is large, and these anomalies are key to determining the future trajectory of the land carbon sink capacity. In this study, we quantify the uncertainty in the interannual variability (IAV) and extremes of the carbon cycle in observations and CMIP6 Earth System Models. While observationally derived GPP estimates show high IAV in the tropics and upper mid-latitudes, the CMIP6 models suggest large IAV in the tropics and lower mid-latitudes with large variability among models. Several CMIP6 models suggest an increase in the magnitude of negative carbon extremes relative to the total GPP toward the end of the century. Furthermore, the negative feedback of temperature anomalies on carbon cycle extremes is relatively instantaneous, predominantly in tropical regions. However, the dominant driver of negative carbon cycle extremes is antecedent anomalous reductions in precipitation that cause a decline in soil moisture. Our results support the hypothesis that the extreme events associated with water limitation will have a larger overall impact on the ecosystem than temperature-driven events, especially in semi-arid regions. The disagreements in the characteristics of the carbon cycle and its extreme events between observations and the models are significant and require an effort from the scientific community to better estimate the uncertainties in carbon uptake in the future. Characterized uncertainty is especially critical when nations are pledging to aggressively reduce their carbon emissions, while simultaneously increasing infrastructure spending and facing growing consumer demand, which have the potential to further increase carbon emissions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.B55G1274S