Earth’s temperature ‘depends on CO2 levels in atmosphere’October 15th, 2010 - 1:53 pm ICT by ANI
Washington, Oct 15 (ANI): A new atmosphere-ocean climate modeling study has shown that the planet’s temperature ultimately depends on the atmospheric level of carbon dioxide and not only on water vapor and clouds.
The study conducted by Andrew Lacis and colleagues at NASA’s Goddard Institute for Space Studies (GISS) in New York examined the nature of Earth’s greenhouse effect and clarified the role that greenhouse gases and clouds play in absorbing outgoing infrared radiation.
Notably, the team identified non-condensing greenhouse gases — such as carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons — as providing the core support for the terrestrial greenhouse effect.
Without non-condensing greenhouse gases, water vapor and clouds would be unable to provide the feedback mechanisms that amplify the greenhouse effect.
A companion study led by GISS co-author Gavin Schmidt that has been accepted for publication in the Journal of Geophysical Research shows that carbon dioxide accounts for about 20 percent of the greenhouse effect, water vapor and clouds together account for 75 percent, and minor gases and aerosols make up the remaining five percent. However, it is the 25 percent non-condensing greenhouse gas component, which includes carbon dioxide, that is the key factor in sustaining Earth’s greenhouse effect. By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth’s greenhouse effect.
The climate forcing experiment described in Science was simple in design and concept — all of the non-condensing greenhouse gases and aerosols were zeroed out, and the global climate model was run forward in time to see what would happen to the greenhouse effect.
Without the sustaining support by the non-condensing greenhouse gases, Earth’s greenhouse effect collapsed as water vapor quickly precipitated from the atmosphere, plunging the model Earth into an icebound state — a clear demonstration that water vapor, although contributing 50 percent of the total greenhouse warming, acts as a feedback process, and as such, cannot by itself uphold the Earth’s greenhouse effect.
“The bottom line is that atmospheric carbon dioxide acts as a thermostat in regulating the temperature of Earth,” Lacis said.
The study’s results have been published in Science. (ANI)
- Global temperatures could rise more than expected - Dec 21, 2009
- Spike in carbon dioxide emissions can cause mercury to rise - Dec 21, 2009
- Dust in Earth's atmosphere has doubled since the beginning of 20th century - Jan 09, 2011
- Slow changes to Earth systems can amplify global warming - Dec 21, 2009
- Healing of ozone hole could aggravate global warming - Jan 26, 2010
- Scientist offers better ways to engineer Earth's climate to prevent global warming - Sep 08, 2010
- Large changes in climate likely over next century - Dec 16, 2009
- Venus could hold warning for Earth - Dec 01, 2010
- Aerosols may impact climate more than estimated - Aug 02, 2011
- Soot on Tibetan snow 'causes more rainfall over India and China' - Mar 04, 2011
- Traveling by car 'contributes to global warming much more than by plane' - Aug 05, 2010
- Dams the latest culprit in global warming - Aug 08, 2012
- Sulphuric acid formation affects climate, health - Aug 09, 2012
- Soot from India triggers retreat of Himalayan glaciers - Feb 04, 2010
- Whitening clouds could fight global warming - Jun 29, 2010
Tags: atmosphere ocean, chlorofluorocarbons, co2 levels, companion study, core support, effect water, feedback mechanisms, gavin schmidt, global climate model, goddard institute, greenhouse effect, greenhouse gas, greenhouse gases, infrared radiation, journal of geophysical research, lacis, minor gases, ocean climate, space studies, water vapor