SAT-EX - Past climate extremes and their impact on the terrestrial carbon cycle

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Context and objectives

Droughts, rainfall extremes and heatwaves are major natural disasters with diverse socio‐economical and environmental consequences. These events cause the failure of food production systems, natural biomass loss, the spread wild fires, air pollution, water scarcity, and multiple other consequences. Our climate models predict the exacerbation and proliferation of such events, following the expected rise in greenhouse gases. Moreover, a series of biotic feedbacks on climate can also be expected, as the intensification of climate extremes severely impacts vegetation biomass and reduces the efficiency of land as a sink of CO2.

The term 'extreme' is applied to those climatic events that are significantly larger than expected,. Analysing these events is challenging given that their frequency of occurrence is low. This is especially problematical when using remote sensing data due to the short lifespan of satellite platforms and sensors. However, recent scientific efforts have yielded global consistent 30–35 years records of climatic and environmental variables through the combination of data from multiple satellite sensors. This timespan appears long enough to start assessing some of the changes in climate extremes and global vegetation dynamics in recent decades.

A trend in the number or intensity of these extremes would be indicative of greenhouse effect," but is a more descriptive term. Climate change refers to the buildup of man-made gases in the atmosphere that trap the suns heat, causing changes in weather patterns."> climate change. SAT‐EX aims to use traditional climate extreme indices derived from remote sensing long-term records, to detect and attribute changes in climatic and environmental extremes using a combination of spatiotemporal clustering methods, fingerprint analysis and random forest machine-learning.

The five objectives of SAT-EX are:

  1. To provide new observational evidence of how droughts, heatwaves and extreme rain events have changed in time and space over the satellite era.
  2. To identify the drivers behind these  changes, e.g., intensification of the hydrological cycle, widening of the tropical belt, ocean-atmospheric oscillations, anthropogenic emission, etc.
  3. To provide satellite-­‐based observational insights into the past changes in global vegetation and the role of extreme hydrological and climatic events on these changes.
  4. To show if IPCC ESMs reproduce the past changes in climatic extremes shown in the satellite records and understand the sources of discrepancies.
  5. To show if IPCC ESMs reproduce the observed changes in vegetation with particular emphasis on the extremes and the vegetation response to hydrological and climatic extremes

 

Project outcome

Expected scientific results

• Consolidation of user requirements report (survey)
• Comprehensive and documented database (web)
• Codes of the statistical framework
• Publications on:
o Vegetation and climate oscillation events from satellite data
o Global variability in past extreme climate events from satellite observations
o Impact on biomass of past extreme events
o Statistical sensitivity of the changes in climate extremes to different climatic variables
o Drivers of long-term vegetation dynamics
o Skill of ESMs at representing global changes in extreme climate events
o Skill of dynamic vegetation models at simulating the impact of extreme climate events on biomass
• Analysis societal implications of our findings, and the suggested roadmap for the future

 

Expected products and services

• New methodologies and insights into the application of remotely-sensed observations and enhanced knowledge regarding recent changes in the Earth climate system. 
• Datasets advertised via the project website.

 

• Climate scientists, hydrologists and remote sensing scientists
• Policy makers mainly by using the Intergovernmental Panel on greenhouse effect," but is a more descriptive term. Climate change refers to the buildup of man-made gases in the atmosphere that trap the suns heat, causing changes in weather patterns."> climate change (IPCC) as platform.
• Weather forecast community
• Earth observation agencies
• Food and agriculture agencies