Quantifying global phenological trends, their drivers, and the effects on terrestrial carbon uptake

Remote sensing data show a widespread increasing trend in gross primary productivity and leaf area index since the 1980s, which can be attributed to both the magnitude of the seasonal greenness and the length of the growing season (phenological shifts). These phenological shifts result in changes in water, nutrient, and energy fluxes hence altering terrestrial carbon uptake under climate change. In this presentation we address the following key questions: i) What are the temporal trends in phenological shifts in Earth's different biomes? ii) What are the main drivers of these shifts across different biomes? More specifically, what is the relative importance of external environmental drivers such as temperature, precipitation, and radiation versus internal vegetation feedbacks such as growth and nutrient limitation? iii) To what extent are phenological shifts of the beginning and end of the growing season determining trends in gross primary productivity? These results are crucial for forecasting long-term changes in the carbon cycle under climate change.