As a phenomenon like the continuing production and growing stocks of greenhouse gases by our industrial societies intensifies, it creates a warming effect that thaws the cryosphere – that part of the planet that is frozen. So, more melting gives more dark surfaces which leads to the earth absorbing more solar radiation which makes it hotter which induces more melting ….. There’s nothing positive at all about the fact that as ice and snow melts, it increases the area of darker surfaces like open ocean water and land that absorb solar radiation, but the fact that the cycle, the feedback loop, grows in intensity as it feeds on itself is said to be “positive” in the sense that it grows.
That the high albedo of snow and white ice makes it more reflective is a reassuring feature of nature. That we are diminishing the albedo of the Arctic, day by day and hour by hour, is deeply disturbing. That we now seek to extract even more fossil fuels in this melting environment is more than disturbing – it’s insane. (See the last paragraph in this item from me on Climate and Security.)
Reuters reports today on a new study that brings renewed focus to the Arctic thaw and its implications. What scientists are finding is an even greater impact than climate models have been predicting. Mark Flanner of the Department of Atmospheric, Oceanic and Space Science (AOSS) at the University of Michigan and lead author of the study, said: “…the cryosphere (areas of ice and snow) is both responding more sensitively to, and also driving, stronger climate change than thought.” The study itself, in Nature Geoscience, finds “that cyrospheric cooling declined by 0.45Wm−2 from 1979 to 2008, with nearly equal contributions from changes in land snow cover and sea ice.” Watts per square meter is the measure of radiative forcing.
It’s worth having this definition from Worldwatch Institute’s very useful Climate Change Reference Guide.
Forcing: Changes to the climate system that are caused by natural (volcanic eruptions, for example) or human-caused (such as greenhouse gas emissions) factors. Scientifically, radiative forcing measures changes to the natural energy balance of Earth’s atmosphere that affect surface temperature. So named because it measures incoming solar radiation against outgoing thermal radiation, radiative forcing is expressed as a rate of energy change in watts per square meter. Human-caused forcing factors like greenhouse gases have a positive radiative forcing and cause surface temperature to heat. Other such factors, including some aerosols, have a negative radiative forcing and cause surface temperature to cool.
