Table 1.

Essential climate variables.

Atmosphere	Ocean	Land
Surface •Precipitation •Pressure •Surface radiation budget •Surface wind speed/direction •Temperature •Water vapor	Physics •Ocean surface heat flux •Sea ice •Sea level •Sea state •Sea surface salinity •Sea surface temperature •Subsurface currents •Subsurface salinity •Subsurface temperature •Surface currents •Surface stress	•Above-ground biomass •Albedo •Anthropogenic greenhouse gas fluxes •Anthropogenic water use •Fire •Fraction of absorbed photosynthetically active radiation •Glaciers •Groundwater •Ice sheets and ice shelves •Lakes •Land cover •Land surface temperature •Latent and sensible heat fluxes •Leaf area index •Permafrost •River discharge •Snow •Soil carbon •Soil moisture
Upper atmosphere •Earth radiation budget •Lightning •Temperature •Water vapor •Wind speed/direction	Biogeochemistry •Inorganic carbon •Nitrous oxide •Nutrients •Ocean color •Oxygen •Transient tracers
Composition •Aerosols properties •CO2, methane, other greenhouse gases •Cloud properties •Ozone	Biology/ecosystems •Marine habitat properties •Plankton

Adapted from The Global Climate Observing System Essential Climate Variable Data Access Matrix (https://www.ncdc.noaa.gov/gosic/gcos-essential-climate-variable-ecv-data-access-matrix).