Greenhouse Gases

Greenhouse Gases

(C) Eric R. Pianka

Until recently, Earth was in a delicate thermal balance with heat gained approximately equal to heat lost, cycling within a fairly narrow range as glaciation produced cooling and deglaciation produced warming with a periodicity of roughly 100,000+ years (Milankovitch Cycles). But now, due to burning fossil fuels over the last century, humans have increased carbon dioxide levels, which in turn have enhanced the greenhouse effect and prolonged the present deglaciation/warming trend for the last 10,000 years, whereas former warm peaks in the cycle were much shorter (again, see the graph below). Holding in more solar energy has lengthened the period of global warming. This latest warm period extends for about 100 centuries and is called "the long summer" (Fagan 2004).

Recently, Ruddiman has proposed that human activities, primarily deforestation, began to alter atmospheric carbon dioxide and methane levels many centuries ago, long before the industrial revolution. If so, global warming may not be a recent development but may have begun nearly 100 centuries ago with the advent of agriculture.

We should be doing everything we can to KEEP this methane locked up in Earth's crust and frozen in the deep oceans. However, people seem to think we can live above the laws of nature and can use all the energy we "need" and want. Fracking cracks deep rocks releasing methane produced by anaerobes much of which vents to the surface and enters the atmosphere. We are also deliberately extracting methane from ocean clathrates and BURNING it for energy. Both fracking and clathrate mining release a lot of waste heat that cannot be dissipated as well as adding more water vapor and carbon dioxide to the atmosphere, further speeding up the rate of global warming. An international consortium involving Canada, the US, Japan, India, and Germany is already extracting methane from clathrates and burning deep sea methane off the north coast of Canada at a place called Mallik. The USGS has nine other similar projects underway scattered around the world. Our voracious appetite for ever more and more energy accelerates the rate of global warming. These ill-fated efforts to use methane as fuel will only hasten climate change. What fools we humans are, rushing to destroy this, our one and only Spaceship Earth!

Another very dangerous man-made molecule, trifluoromethyl sulfur pentafluoride SF5CF3, has recently begun to appear in the atmosphere. Each molecule of this greenhouse gas has 18,000 times the effect of one molecule of carbon dioxide on heat retention. Although SF5CF3 is present in very small amounts, it is exceedingly stable (half life=1000 years) and is increasing at a rate of about 6% per year [Sturges et al (2000) Science 289:611-613].

9 January 2014 by Eric R. Pianka