Posted by: ericgrimsrud | September 30, 2012

Loss of Sea Ice

I happen to think that the most damaging change about to occur in the next decade or two will be the loss of our Arctic Sea Ice during the Northern Hemisphere (NH) summertime.  Measurements suggest that this change is about to occur by the time my young grandchilden graduate from college.

This change will cause enormous additional warming on top of that which is already occurring due to our continuously increasing levels of greenhouse gases.  Imagine changing the Arctic from a snow and ice covered place to an open ocean.  Snow covered ice reflects about 90% of incoming sunlight back out into outer space while an open, ice-free ocean will reflect much less, about 10% to 20% depending on the angle of incidence.  In the NH summertime when the NH is tilted towards the Sun so that the entire Arctic region is exposed to sunlight all day long for several months, there will be a lot more solar radiation being deposited onto our planet and specifically into the Arctic Ocean as this layer of ice dissappers.

Perhaps the most troublesome outcome of a warming Arctic Ocean is what is likely to then occur in its depths below. The floor of the Arctic Ocean contains vast quantities of decayed organic matter that was deposited there some tens of millions of years ago when Alaska, for example, had a tropical climate home to alligators and abundant vegetation. A final product of the anaerobic decay of plant material is methane, CH4, which would normally escape to the atmosphere if not prevented by other physical processes. Over time as the entire planet cooled and an Arctic sea ice progressively grew, the depths of the Arctic Ocean also cooled to a point where the methane being produced within the ocean floor was no longer allowed to escape to the atmosphere above. This is because if the temperature is sufficiently low and the pressure sufficiently high at the ocean’s floors, methane combines with water to form a rather exotic form of solid ice, called methane clathrate, in which one molecule of CH4 is trapped in an ice crystal of about 15 water molecules. That molecule of methane is thereby immobilized in the ocean bottom until it can be released for some reason – such as an increase in temperature.

Estimates of how much methane is thereby locked up under the Arctic Ocean vary a great deal with some suggestions being that the carbon content in it exceeds the sum of all know reserves of natural gas, oil, and coal. In addition, as the Arctic has been warming significantly in the last decades, observations of increased methane emissions from various coastal shelves of the Arctic are being observed. All of this presents that worst of all possibilities associated with a warming world – what’s called a runaway greenhouse effect in which increased temperature causes increased emissions of methane which, in turn, causes increased temperature, which causes increased emissions, which…. etc, until essentially all of the trapped methane has been released to the atmosphere. With an occurrence such as this, the Earth would experience a change from one distinct climate state to another relatively quickly that could not be prevented by any conceivable actions by man.

The only positive aspect of this looming problem is that it’s occurrence and easier-to-understand scientific basis just might possibly and finally force our political and industrial leaders to admit that planet Earth has a huge problem and that is one that must be addressed immediately before its too late.  Very wishful and probably unwarrented thinking, I will admit, to think that there might be a limit to the utter stupidity of Man.


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