TCS Daily


Pentagonal Poppycock

By Robert C. Balling - March 1, 2004 12:00 AM

Recent headlines on global warming trumpet incredible horrors from a Pentagon report on how abrupt climate change could threaten our national security. The storyline is straight out of the upcoming blockbuster movie entitled "The Day After Tomorrow." Humans (particularly those in the United States) continue to pour greenhouse gases carelessly into the atmosphere, the ocean-atmosphere system crosses some critical threshold, the conveyer belts moving heat through the world's oceans collapse (e.g., bye-bye Gulf Stream), and very quickly, the climates of Europe and North America become substantially colder, drier, and more windy. The report details how our national security would be threatened by resultant battles over food, fresh water, and energy.

The authors of the report, Peter Schwartz and Doug Randall, point out that "Many scientists would regard this scenario as extreme both in how soon it develops, how large, rapid and ubiquitous the climate changes are." They argue that in an anything-is-possible world, we should carefully evaluate the problems such a climate event would have on our national security. Fair enough, but we could all generate a "what if scenario" for the future and fill newspapers with headlines day after day, much to the delight to the environmental community constantly promoting the global warming crusade.

However, a quick trip to the science library will show that the probability for this scare is closer to zero than it already is! A paper just published Global and Planetary Change focuses on what happens to ocean heat transfers in the North Atlantic as greenhouse gas concentrations continue to increase. The scientists used a coupled ocean and atmosphere computer model with a one percent per year increase in carbon dioxide (CO2) levels. The authors (Bleck and Sun, 2004) found that "the Atlantic overturning stream function appears to be stable," and is "insensitive to global warming resulting from gradual CO2 doubling." The translation is simple -- relax, the Gulf Stream is going to be around for a very long time!

This important conclusion is reinforced by another recent paper published in Geophysical Research Letters by a trio of scientists from the United Kingdom. Wu et al. (2004) used numerical climate model simulations that included variations in solar output, volcanic eruptions, and changes in atmospheric composition associated with CO2, sulfur dioxide, and ozone. They found similarities between model outputs and global temperatures and sea conditions in the North Atlantic Ocean, but they found no decreasing trend in the strength of the ocean circulation and heat transfer for a buildup in greenhouse gases. In fact, the authors found the strength of the ocean circulation "unexpectedly shows an upward trend, rather than a downward trend" as we move forward in this century.

Thirty years ago we were told to fear global cooling; over the last 15 years we have been asked to lose sleep over global warming, and here we are again supposedly concerned about a threat of sudden and severe cooling. Apocalyptic predictions about nuclear winter and some never-realized massive climate effect of the Kuwait oil fires made their rounds in this same short time period.

You are certainly excused if you are having trouble warming-up to this latest scare about imminent and catastrophic cooling.

Readings

Bleck, R. and S. Sun. 2004. Diagnostics of the oceanic thermohaline circulation in a coupled climate model. Global and Planetary Change, 40, 233-248.

Wu, P., R. Wood, and P. Stott. 2004. Does the recent freshening trend in the North Atlantic indicate a weakening thermohaline circulation? Geophysical Research Letters, 31, 10.1029/2003GL018584.

The author recently wrote for TCS about our gift to Christmas trees.


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