Remote sensing - The Carbon Cycle

The increasing global mean air temperature and other climatic changes are driven by the increase of atmospheric greenhouse gas concentrations, of which carbon dioxide (CO₂) is the most important. The concentration of CO2 in the atmospheric is not only influenced by anthropogenic CO₂ emissions, but also by the exchange of CO₂ between the atmosphere and the biosphere. This exchange is an important ecosystem service mitigating climate change since vegetation on land absorbs globally on average 30% of the anthropogenic CO₂ emissions.

Improved understanding of the distribution in photosynthesis and respiration

The net exchange of CO₂ is the difference between the photosynthesis that absorbs and the respiration that releases CO₂. An improved understanding of the distribution in photosynthesis and respiration is therefore essential to better understand, quantify, and forecast the effects of climate change, and is of relevance for climate change mitigation policies designed to reduce atmospheric CO₂ concentrations.

With satellites, we measure the amount of solar radiation that is absorbed by the Earth surface. Since photosynthesis is linked with absorption of solar radiation by the plants, we can use satellites to estimate the amount of CO₂ absorbed by the vegetation. Satellites can also be used to estimate the land surface temperature, which is a key driver of the respiration of CO₂ back to the atmosphere. We thereby use satellite data to map these CO₂ exchange processes. However, the satellites have been around for a long time now, and we thereby also use satellite data for studying the trends and long-term dynamics in these CO₂ exchange processes.

Quantifying the carbon dioxide exchange globally

We study these carbon cycle processes from plot to global scale, using satellite data for ecosystem-scale studies all the way from the Tropical forests to the High-Arctic tundra. These data are used for improving our understanding of how ecosystems are functioning, and how ecosystems are affected by climate and land use changes. We also use data to improve our understanding of how well climate change mitigation and adaptation strategies work.

Quantifying the CO₂ exchange globally to understand of how different areas contribute to the global carbon cycle is particularly important for improved quantifications of national contributions of sinks and sources of CO₂ within the Paris Climate Agreement. Our studies thereby have a strong societal benefit and increases our understanding of Earth processes increasing the capability to predict environmental changes. This enhances the possibilities to make better informed decision making and is of high relevance for many of the UN Sustainable Development Goals.