Atmosphere-biosphere interactions

Human life depends intimately on interactions between Earth’s atmosphere and biosphere. Plants provide the oxygen we breathe, remove the carbon dioxide we exhale, and, through transpiration—the biologically controlled evaporation of water from plant leaves—provide much of the water that rains on our crops and fills our reservoirs.

In more subtle ways, atmosphere-biosphere interactions influence the health of the air we breathe (see figure): rough surfaces of vegetation remove aerosols, ozone, and other reactive gases from the air through dry deposition; plants emit a huge variety of volatile organic compounds (VOCs) that are precursors to tropospheric ozone and aerosols; and the terrestrial biosphere sequesters almost 30% of fossil fuel carbon dioxide (CO2) emissions. Air pollutants also affect the biosphere in turn. Ozone and acid deposition suppress plant growth; meanwhile, aerosols and their indirect effects on clouds decrease total photosynthetically active radiation (PAR) while increasing the diffuse fraction.

We are using satellite and ground observations to test and improve the way these interactions are represented in numerical models.