Volcanos in Gakkel Ridge NOT responsible melting the Arctic iceJuly 10, 2008
I am not only a global warming skeptic, but a skeptic in general. I call ’em as I see ’em.
The truth is that all the energy from a volcano the size of Mount St. Helens could only melt 100 square kilometers of three meter thick ice. This is a trivial amount of ice for the arctic region, which typically oscillates between about 4 million and 14 million square kilometers every year. 100 square kilometers is only one hundred thousandth of the yearly change in Arctic sea ice extent
Arctic region showing the location of the Gekkal ridge. This Google Earthimage, with annotation by Moriarty, obviously does not show the arctic sea ice.
Let’s do some simple math to work this out:
First, how much energy is released by a volcano? Of course, if varies greatly, but we just need an order of magnitude approximation for now. A common estimate for the energy released by the Mount St. Helens explosion is 24 megatons, where a megaton is supposed to be equivalent to the energy released by a million tons of TNT. A joule is the basic SI unit for energy, and one megaton is equal to 4.2 million billion joules (4.2e+15 joules). Therefore the 24 megatons released by Mount St. Helens translates into about 100 million billion joules (1.0E+17 joules). That is:
(4.2E+15 joules/megaton X 24 megatons = 1.0E+17 joules).
So now the question is: how much ice could be melted by 100 million billion joules of energy? It takes about 4 joules to heat one gram of water by 1 degree C. But it takes many more joules to melt a gram of ice. The amount of energy needed to melt a gram of a solid to a liquid is called the “heat of fusion.” The heat of fusion for water is 334 joules per gram. If we divide the total energy of the volcano by the heat off fusion of water, we will get the number of grams of ice that could be melted. Doing the math:
1.0E+17 joules / 334 joules per gram = 3.0E+14 grams
OK, the energy released by Mount St. Helens would melt about 3.0E+14 (three hundred million million) grams of ice. A gram of ice is about 1.1 cubic centimeters (1.1 cc), so we can round it to 1 cc just to make things simple. That means that Mount St Helens released enough energy to melt 3.0E+14 cubic centimeters of ice.
Let’s get a handle on what “3.0E+14 cubic centimeters of ice” means. A cubic meter of ice is the same as 1,000,000 cubic centimeters of ice. So, 3.0E+14 cubic centimeters of ice are the same as 3.0E+8 cubic meters of ice. Still a pretty big number to grasp. A sheet of ice that is one meter thick and one square kilometer would have a volume of 1 million cubic meters (1.0E+6 m3). In this case, 3.0E+8 cubic meters of ice would be the same as 300 square kilometers of ice that is 1 meter thick.
Now we have a number that is easier to deal with. That is, the energy of Mount St. Helens would be enough to melt 300 square kilometers or ice that is 1 meter thick. Finally, we’ll make the estimate that the ice is about 3 meters thick in the arctic. (Of course, it is much thicker some places and much thinner in others.) Then the energy of Mount St. Helens would melt about 100 square kilometers of ice in the Arctic.
The bottom line
The Arctic goes through some serious changes in sea ice extent every year as the season change. The sea ice extent changes by about 10 million square kilometers every year. 100 square kilometers is about one hundred thousandth of that. It would take a thousand volcanos the size of Mount St. Helens every year to account for just 1% of the yearly Arctic ice loss.
I am not only a global warming sceptic, but a skeptic in general. I call ’em as I see ’em.
Mount St Helens explosion, May 18th, 1980.