Global impacts of hydrological and climatic extremes on vegetation (SAT-EX)

Friday, 19 December 2014
Willem Waegeman1, Niko Verhoest2, Mathieu Depoorter2, Pierre Regnier3, Pierre Friedlingstein3,4, A Johannes Dolman5, Richard de Jeu6, Wouter Dorigo7 and Diego G Miralles2,6, (1)Ghent University, Department of Mathematical Modelling, Statistics and Bioinformatics, KERMIT Research Unit, Ghent, Belgium, (2)Ghent University, Laboratory of Hydrology and Water Management, Ghent, Belgium, (3)Université Libre de Bruxelles, Department of Earth and Environmental Sciences, Brussels, Belgium, (4)University of Exeter, College of Engineering, Mathematics and Physical Sciences, Exeter, United Kingdom, (5)Free University of Amsterdam, Department of Earth Sciences, Amsterdam, 1081, Netherlands, (6)Free University of Amsterdam, Department of Earth Sciences, Amsterdam, Netherlands, (7)Vienna University of Technology, Department of Geodesy and Geoinformation, Vienna, Austria
Global warming is expected to increase the frequency and severity of droughts, extreme precipitation events and heatwaves. Recent studies have underlined the critical impacts of these extremes on the terrestrial carbon cycle, particularly on the dynamics of vegetation. Yet, the latest IPCC report reveals large uncertainties in extremes trends and biomass impacts. Conversely, new advances in satellite Earth observation have led to the recent development of consistent global historical records of crucial environmental and climatic variables – like surface soil moisture, soil water storage, terrestrial evaporation or vegetation water content. These datasets provide alternative means to unravel the processes driving past climate extremes, uncover the spatiotemporal scales at which these extremes operate and understand their impact on terrestrial biomass.

The SAT-EX project (funded by BELSPO) recently raised with the purpose of exploring the potential of the state-of-art remote sensing datasets to study the causes and consequences of the spatiotemporal changes in wet, dry and warm spells over the past three decades. Core methodologies involve the analysis of satellite-based climate extreme indices and vegetation characteristics through a novel combination of machine learning methods and fingerprint identification approaches. First results will show how droughts, heatwaves and extreme rain events have changed in frequency and intensity since the '80s, and attribute these changes to on-going processes like the widening of the tropical belt, ocean-atmospheric teleconnections, the intensification of land-atmospheric feedbacks or the overall rise in greenhouse gasses (and expected acceleration of the hydrological cycle). At the same time, our analyses will uncover the effects of climate extremes on large-scale vegetation dynamics.

Further phases in the project will involve the evaluation of IPCC Earth System Models on the basis of their skill to reproduce the effects of climate extremes on vegetation. In the long run, SAT-EX findings will advance towards the timely forecasting of climate extremes, provide valuable insights about the management of water resources during these events and reduce the uncertainty in long-term IPCC predictions of climate extremes and global vegetation variability.