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

You are here

Context and objectives

Advances in satellite remote sensing and high-performance computing in recent years are opening up new
possibilities to investigate our biosphere, hydrosphere and atmosphere, from sub-daily to multi-decadal time
scale. In this new era of information technology, routine satellite observations can be used to: (a) provide
process understanding about the drivers of vegetation dynamics at increasingly higher resolutions and
planetary scales, and (b) benchmark the representation of vegetation dynamics in ESMs. Given the nonstationary
tendency of our climate system, the emphasis of ESM benchmarking should be placed on correctly
characterising in our models the cause–effect links between vegetation and its multiple climatic drivers. In
other words: present-day vegetation dynamics should not only be correctly represented in our ESMs, but also
'right for the right reasons'. Only then the ability of ESMs to represent the future state of our ecosystems
would be reliable. Some recent studies have already used long-term satellite datasets on their own with the
focus of studying past extremes; others have applied them with the explicit goal of evaluating climate model
representation of general average hydro-climatic patterns. Conversely, the ESM representation of climate
extremes has been evaluated by comparison to reanalysis and in-situ measurements. However, long-term
remote sensing datasets have not yet been applied to evaluate the global-scale variability of precipitation and
temperature extremes in climate models and identify their role in ongoing changes in global vegetation dynamics.

The objectives of SAT-EX strive in that direction.

  1. To provide evidence of how climate extremes have changed over the satellite era and identify the drivers
    behind these changes (Objective 1).
  2. To provide new insights into past changes in vegetation and the role of climate and climatic extremes on these
    changes (Objective 2).
  3. To test the extent to which IPCC ESMs reproduce the changes in climatic extremes and the associated
    response of vegetation (Objective 3).

Project outcome

Expected scientific results

 

 

Expected products and services

 

 

 

 

Results

1. Climate extremes have substantially changed in frequency and intensity over the satellite era.
2. Climate has a causal effect on vegetation in most of the continental land.
3. More than half of the continental vegetated area is primarily controlled by water availability.
4. Hydro-climatic conditions have a substantial effect on vegetation browning events.
5. Hydro-climate biomes can be directly identified from the observational data by advanced machine-learning.
6. Satellite-observed atmospheric composition can help detect the influence of climate extremes on vegetation.
7. The influence of climate on vegetation dynamics in ESMs is underestimated.
8. Climate models agree on water availability being the most relevant global constraint on vegetation dynamics.
9. Just below 3% of global annual GPP is lost via compound climatic extremes.
10. Climate models may overestimate the magnitude of interannual variation in NEP.

Products and Services

The main products that are delivered are new methodologies and insights in (a) the application of remotely
sensed observations, and (b) recent changes in the Earth climate system. The products are initially distributed in
the form of contributions to different international conferences, journal publications, and through data and code
sharing via public repositories (https://github.com/lhwm/) and project website (http://www.sat-ex.ugent.be).

Potential Users

As described above, given the fundamental scientific objective of the project to evaluate satellite records to
enhance our understanding of hydro-climatic extremes and their ecosystem impact, the potential users mainly
consist of climate scientists, hydrologists and remote sensing scientists. End-users interested in these findings
may include: (a) the climate modelling community and climate-related entities (e.g. IPCC, WMO), (b) the
weather forecast community (e.g., ECWMF), (c) Earth observation agencies (e.g. ESA, NASA), (d) entities
looking specifically at the impact of these extremes on agriculture and ecosystems (e.g. USDA, FAO, UNESCO),
or (f) different scientific research teams working on related topics.