Earth’s Energy Imbalance and Climate: An Observational Perspective

Increasing concentrations of well-mixed greenhouse gases (WMGG) in the atmosphere have led to an imbalance between how much solar radiant energy is absorbed by Earth and how much thermal infrared radiation is emitted to space. This net radiation imbalance, also referred to as Earth’s energy imbalance (EEI), has led to increased global mean temperature, sea level rise, increased heating within the ocean, and melting of snow and sea ice. In addition to anthropogenic radiative forcing by WMGG, EEI is influenced by aerosol emissions and land use change as well as by natural forcings associated with volcanic emissions and variations in solar irradiance. As the climate system responds to warming, changes in clouds, water vapor, surface albedo and temperature further alter EEI. At decadal timescales, internal variations within the climate system also play an important role. Recent satellite and ocean in situ observations indicate an alarming doubling in EEI between 2005 and 2019. This presentation will introduce the concept of EEI, describe the observing system used to measure it, present the observational evidence for a doubling in EEI, and discuss possible reasons for its increase.