Radiative Forcing

     Radiative forcing (RF) describes the difference between the energy that is gained by Earth and then later lost to space.  The IPCC uses radiative forcing with assessments, “to denote an externally imposed perturbation in the radiative energy budget of Earth’s climate system, which may lead to changes in climate” (Braun, 2013).  Greenhouse gas concentration can change and cause a disturbance in the radiative forcings that are calculated.  It is used to assess and compare natural and human related drivers of climate change.  It ranks and quantifies the different influences of climate change but doesn’t represent overall climate responses (IPCC, 2007).

     Radiative forcing can be related to the greenhouse effect as well, both natural and human enhanced.  The imgage belshows a number of radiative forcing drivers, the first two bars, both red, are greenhouse gases, mainly driven by human forces.  Both of these have a large radiative forcing affects.  CO₂ emissions cause an increase of RF.  This is due to the fact that carbon dioxide influences the amount of heat that is captured within the atmosphere.  The more heat that is captured due to that specific greenhouse gas, which is influenced by human activities such as driving cars, the higher the radiative forcing bar for that driver.  The third bar that is shown depicts ozone RF, depending on the good or bad ozone there is either a negative or positive RF, which can also be affected by human activities.  

A simple graph showing the components of radiative forcing.  Bars in red show where heat is added while bars in blue show cooling influences.  Heating affects have positive values, while cooling affects have negative values.

Braun, Carsten. 2013. The Concept of Radiative Forcing. Handout.

IPCC. 2007. "2.2 Concept of Radiative Forcing - AR4 WGI Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing." IPCC - Intergovernmental Panel on Climate Change. N.p., n.d. Web. 22 Feb. 2013. <http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-2.html>.