Essential Climate Variables

Atmosphere

Surface

• Precipitation
• Pressure 
• Radiation budget
• Temperature 
• Water vapour 
• Wind speed and direction 

Upper-air

• Earth radiation budget 
• Lightning 
• Temperature 
• Water vapor 
• Wind speed and direction 

Atmospheric Composition

• Aerosols 
• Carbon dioxide, methane and other greenhouse gases 
• Clouds 
• Ozone 
• Precursors for aerosols and ozone 

Land

Hydrosphere

• Groundwater 
• Lakes 
• River discharge

Cryosphere

• Glaciers
• Ice sheets and ice shelves
• Permafrost
• Snow

Biosphere

• Above-ground biomass
• Albedo
• Evaporation from land
• Fire
• Fraction of absorbed photosynthetically active radiation (FAPAR)
• Land cover
• Land surface temperature
• Leaf area index
• Soil carbon
• Soil moisture

Anthroposphere

• Anthropogenic Greenhouse gas fluxes
• Anthropogenic water use

Ocean

Physical

• Ocean surface heat flux 
• Sea ice
• Sea level
• Sea state
• Sea surface currents
• Sea surface salinity
• Sea surface stress 
• Sea surface temperature
• Subsurface currents 
• Subsurface salinity 
• Subsurface temperature

Biogeochemical

• Inorganic carbon
• Nitrous oxide
• Nutrients
• Ocean colour
• Oxygen
• Transient tracers

Biological/ecosystems

• Marine habitats
• Plankton