Saturday October 19
10AM to 11AM
Human life on Earth has always depended on natural levels of greenhouse gases. The Earth absorbs visible light from the sun and, to stay in energy balance in the global and seasonal mean, must emit an equal amount of energy back into space.
The effective temperature at which the earth radiates to space is about -18 °C while the global annual surface temperature has been about 15 °C, a 33 °C difference.
Partly this separation between surface and effective temperature is a direct effect of the non-precipitating greenhouse gases and partly an effect of their control of the amount of water vapor in the atmosphere, itself a strong greenhouse gas.
There is no physical reason that increases in carbon dioxide and methane from human activities would not continue to increase the mean surface temperature to maintain the effective radiative temperature.
This change in global, annual mean surface temperature is what we call global warming, but it is only part of the story.
Read the announcement in full here (link).
http://maps.secondlife.com/secondlife/The%20Science%20Circle/67/129/32
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