Editing Greenhouse effect (section)

=== Effective temperature ===
[[File:Effective temperature for climate thermal radiation.svg|thumb|Temperature needed to emit a given amount of thermal radiation.]]
The power of outgoing longwave radiation emitted by a planet corresponds to the ''[[effective temperature]]'' of the planet. The effective temperature is the temperature that a planet radiating with a uniform temperature (a [[blackbody]]) would need to have in order to radiate the same amount of energy.

This concept may be used to compare the amount of longwave radiation emitted to space and the amount of longwave radiation emitted by the surface:

* ''Emissions to space:'' Based on its emissions of longwave radiation to space, Earth's overall ''effective temperature'' is {{convert|-18|C}}.<ref>{{cite web |url=http://eesc.columbia.edu/courses/ees/climate/lectures/radiation/ |title=Solar Radiation and the Earth's Energy Balance |publisher=Department of Earth and Environmental Sciences, Columbia University |access-date=15 October 2010 |archive-date=17 July 2012 |archive-url=https://archive.today/20120717025320/http://eesc.columbia.edu/courses/ees/climate/lectures/radiation/ |url-status=dead }}</ref><ref name="IPCC4_ch012"/>
* ''Emissions from surface:'' Based on thermal emissions from the surface, Earth's ''effective surface temperature'' is about {{convert|16|C}},<ref name="ipcc-ar6wg1-ch7" />{{rp|934}} which is {{convert|34|C-change}} warmer than Earth's overall effective temperature.

Earth's surface temperature is often reported in terms of the average near-surface air temperature. This is about {{convert|15|C}},<ref name="clchgtrack"/><ref>The elusive "absolute surface air temperature", see [http://data.giss.nasa.gov/gistemp/abs_temp.html GISS discussion] {{Webarchive|url=https://web.archive.org/web/20150905093320/http://data.giss.nasa.gov/gistemp/abs_temp.html |date=5 September 2015 }}</ref> a bit lower than the effective surface temperature. This value is {{convert|33|C-change}} warmer than Earth's overall effective temperature.