One of the reasons I accept the idea that human activities, such as burning fossil fuels, is contributing to global warming beyond the Earth’s natural rhythms is that I find most arguments given by the opponents of this concept to be faulty. This is especially true, unfortunately, in the conservative Christian media. In my daily web browsing this morning, for example, I came across an article on a widely-read, conservative Christian magazine site which had some really bad science on global warming.
The article was based on two recent news reports. The first of these was a report of record melting of Arctic sea ice, to the point that the North Pole might be ice-free for part of the summer this year. The melting of polar ice, of course, has been in the news frequently, and this thawing could have many consequences, environmental and political. The second report was that scientists recently discovered that the rate of volcanism along the mid-ocean ridge, deep on the floor of the Arctic Ocean, is much higher than had been previously predicted. The author of the article jumped to the conclusion that it is obviously the volcanism that is causing the melting of sea ice. After all, volcanoes not only release a lot of heat, they release carbon dioxide. This double-whammy, according to the author, was a sufficient explanation for the thinning of the ice in the Arctic.
There are two major problems with this argument.
First, the volume of the water in the Arctic Ocean is immense compared to the volume of lava extruded. The author of this article doesn’t realize that heating the Arctic Ocean by mid-ocean ridge volcanism would be like heating an Olympic sized swimming pool by occasionally lighting a match. In addition to the huge volume of water—the Arctic contains about fifteen million cubic kilometers of water—one needs to take into account the heat capacity of water. Heat capacity is a measure of how much heat it takes to increase the temperature of a substance. One of the important physical properties of water is its unusually high heat capacity, which means that it takes a tremendous amount of heat to make water change its temperature by a small amount. If one places an empty pan on a hot burner, the metal will heat up very quickly. On the other hand, if one places a water-filled pot on the same burner, it will take much longer to heat up (a watched pot never boils!). Likewise, the small amount of heat added to the Arctic by mid ocean ridge volcanism isn’t sufficient to have a measurable effect on the overall temperature of the polar ocean.
Another point of confusion in the article was the thought that the carbon dioxide released by these submarine eruptions somehow dwarfs CO2 that is released by human activity, and perhaps even stays concentrated over the Arctic ice pack. This is part of the urban legend that floats around conservative web sites that says that the amount of CO2 released by a single volcanic eruption is greater than what humans release to the atmosphere through burning fossil fuels. The truth is that the carbon dioxide released by these Arctic eruptions is tiny compared to the CO2 released worldwide by volcanoes, and the amount of CO2 released by volcanoes is tiny compared to the amount of CO2 released by human activities. According to the US Geological Survey:
- Annual volcanic production of CO2: 130-230 million metric tons
- Annual human production of CO2: 27 billion metric tons
- Therefore, human production of CO2 is at least 100 times greater than volcanic production
Additionally, the CO2 released by seafloor Arctic volcanism will either stay in solution in the water, or become evenly mixed and dispersed in the atmosphere.
The record melting of Arctic sea ice has absolutely nothing to do with seafloor volcanism. It is one thing to be skeptical of global warming, but the poor scientific reasoning expressed in this article does no one a service.