Oceanographers Fear a Return of the Little Ice Age

August 3, 2002

by Bob Webster - Editor at Large

Is a return to the frigid climate of the Little Ice Age imminent? According to oceanographers at Woods Hole Oceanographic Institute on Cape Cod in Massachusetts, there is a real near-term threat that average temperatures over much of the United States could drop by five degrees Fahrenheit with the Northeast U.S., northern Europe and northern Asia experiencing twice that degree of climate cooling.

But aren't we supposed to be in a period of global warming because humans are burning too much fossil fuel? How can this be?

Well, according to Terrence Joyce, chairman of the Woods Hole Physical Oceanography Department, such a scenario is not only possible, it could begin "in 10 years [and once] it does, it can take hundreds of years to reverse." In April Joyce wrote, "Recall the coldest winters in the Northeast, like those of 1936 and 1978, and then imagine recurring winters that are even colder, and you'll have an idea of what this would be like."

But, wait a minute. Aren't we experiencing global warming? Well, for now, maybe. But as climate history shows, periods of warming and cooling are part of the natural cycles of Earth's climate changes.

According to an article in the September 2002 issue of Discover magazine, the basis for oceanographer's concerns is the possibility that the Gulf Stream, a current of warm ocean water that warms the Northeast U.S. and, to a greater extent northern Europe and northern Asia, could be significantly curtailed or interrupted entirely.

The Discover article cautions, "Still, climate science is devilishly complex, and the onslaught of a little ice age is not certain, at least at this stage of the research."

The culprit, according to the Discover article, is "the appearance over the past 30 years in the North Atlantic of huge rivers of freshwater - the equivalent of a ten-foot thick layer - mixed into the salty sea." While there is no certainty of the source of this freshwater, one culprit is thought to be melting Arctic ice as a result of recent climate warming - despite the fact that Arctic warming didn't occur until the past 15-20 years! Nevertheless, regardless of the source, or the cause of the source, the effect of this large freshwater influx is to act as a "big thermal blanket" sitting atop the ocean since freshwater is less dense than saltwater. This freshwater blanket "could make the Gulf Stream slow or veer southward … [and at] some point the whole system could simply shut down, and do so quickly" according to the Discover article.

I encourage any interested reader to read the Discover article for an explanation of thermohaline circulation and how these ocean currents affect and respond to changes in climate.

If the prediction of an imminent return of a little ice age is credible, shouldn't we be concerned about what steps humans can take to mitigate the sudden and dramatic cooling?

Should we reconsider greenhouse gas abatement in favor of increased greenhouse gas emissions? After all, if humans can, indeed, affect climate, wouldn't it be prudent to get our climate furnace heated up if we're about to be plunged into another little ice age?

An intriguing question. As with all human attempts to regulate the environment, we run enormous risks when we embark on plans for change when the consequences of such change are not adequately considered or understood.