Fundamental Research Division
The DRF at the CEA assemble approximately 6,000 scientists since January 2016.
Scientific result | Climate | Carbon cycle
Although the annual carbon footprint seems to be driven by temperature at the global scale, water availability appears to be the dominant factor at the local scale. A study in which LSCE researchers participated sheds new light on this paradox.
Terrestrial ecosystems are the main cause of interannual variations in the carbon cycle. Why, then, do they seem to be driven by the tropical temperature when looking at the global scale and by water resources when looking at the local scale?
In a systematic modelling approach, climate scientists have analyzed the effects of temperature and precipitation on carbon exchange between the atmosphere and the terrestrial biosphere, from small areas up to the global surface of the Earth.
Photosynthesis and the respiration of plants and microorganisms are driven by water availability and these effects partially compensate each other. Yet, on a larger scale, the influence of water decreases, since exceptional drought in one part of the world is often compensated by exceptional precipitation in another.
This study points to the need for a better understanding of how climate variables change across different space scales. The simple relationship observed today between temperature and the global land carbon sink should be treated with caution, and should not be used to make long-term predictions. According to the scientists, the water cycle could become a critical factor for the terrestrial carbon sink on a global scale.
Compensatory water effects link yearly global land CO2 sink changes to temperature, Nature.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.