| Understanding the role of climate extremes is increasingly in the focus of Earth system sciences and highly relevant to climate change assessments In particular, we need a precise understanding of the impact of extreme events on the terrestrial biosphere in order to quantify the relevance for, and feedbacks with, the climate system. Previous studies have shown that climate extremes may have severe regional effects on the carbon cycle, but a state-of-the-art global impact assessment is still lacking. Hence, we quantify the impact of extreme anomalies in the state of vegetation on the global gross primary productivity (GPP). Using a definition of less than 5% chance of occurrence, we estimate that the 100 largest extreme events experienced by the terrestrial biosphere over the last 30 years are responsible for a decrease in carbon uptake of about 30 Pg C. We find that most extremes are best explainable by phases of water scarcity in the ecosystems, particularly relevant for crops. An analysis of the results from the "Coupled Model Intercomparison Project Phase 5" (CMIP5) reveals that the magnitude of biospheric extremes tends to increase. |
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