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Serious Stuff

Has Global Warming Forever Ended Ice Age Cycles?

by Somebody Else
March 18, 2011

I was talking with a friend of mine the other day about global warming. He is a very educated man with a PhD in Mathematics and is an assistant professor at a prestigious university. True, he is not an expert on matters of climate and the weather, but in any case, one might reasonably assume that his take on the topic of global warming would be worth some serious consideration.

While we both agree that human activity has led to and is continuing to lead to a progressive increase in global temperatures, we see the long-term consequences differently.

"The ice ages have ended forever," he stated with complete confidence, with a firm smile spread across his face. "We human beings will always keep expelling such a large quantity of greenhouse gases into the atmosphere that an ice age can never again return."

He did not see this as a terrible problem.

"The seas will rise, it is true," he remarked. "But this will be gradual, so that people on the coast will have sufficient time to move further inland."

I particularly objected to this last point, which seemed to me overly optimistic, but decided to allow him to continue without interrupting him.

"The warm climate will remove all of the ice from the poles. Large numbers of people will be able to migrate to Antarctica. The Arctic Sea will be free of ice and will provide an excellent shipping lane between Asia and the West."

I suspect that this particular perspective is quite common throughout the world. As the concept of global warming has gained widespread acceptance everywhere, and has steadily taken on the status of fact as opposed to mere scientific theory, it has been natural for many people to assume that we humans are in the process of permanently banishing cold from our planet. All too often, global warming is seen as signaling the final end to customary global climate cycles.

However, there are several problems with such a view, which I will consider at length.

We should begin our investigation of this important matter by going back in time three million years. During that era, the Isthmus of Panama was formed, a land bridge connecting the North and South American continents. This formation separated the Atlantic and Pacific Oceans and rerouted currents, leading to the creation of the Gulf Stream, which since that time has been transferring Caribbean warmth, and hence greater levels of precipitation, to the northern reaches of the globe. The relatively warmer and snowier weather in these areas in turn led to the formation of a large Arctic ice cap -- the greater the amount of moisture, the more snow and ice can be formed -- and thus to the ice age cycles of the last three million years, according to which we periodically transition back and forth between epochs of extreme cold and moderate warmth.

One key principle of long-term climate study, known as paleoclimatology, is that snow and ice tend to be self-perpetuating. Weather forecasters today know this, and must take it into account even with short term forecasts.

For example, if a weather forecaster knows that there is significant snow cover over a large geographic area, she must make allowances for the chilling effect that it will have on the surrounding air. Dark, exposed ground absorbs more energy from the sun's rays than snow does, heats up more, and transfers more warmth to the surrounding air. Snow and ice, on the other hand, tend to reflect out into space most of the energy coming from the sun's rays.

So, a large area of land covered by snow and ice tends to chill the air above it, and this chilled air tends to spread out towards warmer areas. Snow will often fall where cold and warm masses of air meet, and this fallen snow will chill the surrounding air, etc. Thus, cold can build upon cold through the instrumentality of frozen precipitation that accumulates on the earth's surface.

This is the essential dynamic that led to the buildup of massive ice sheets thousands of feet thick that descended from the northern regions of the planet and gouged out the Great Lakes at the border of Canada and the United States. And even though the ice sheets of Greenland are currently melting at an alarming rate, lest we forget, they are still so huge that they create their own climate and have been essentially self-perpetuating since the end of the last ice age.

Returning to the topic of the Isthmus of Panama, we see that since the ocean currents have more or less had their present configuration beginning three million years ago, we have experienced a regular cycle of ice ages, which come and go depending upon a number of factors, such as fluctuating carbon levels in the atmosphere, the variable tilt of the earth's axis over very long periods of time, the fluctuating intensity of the sun's output throughout the millennia, the long-term buildup and melting of snow and ice, etc. The context for these cycles is the present arrangement of the earth's major land masses and the resultant ocean currents, which effectively regulate the transference of heat energy over much of the globe.

In other words, under the present global configuration, we should expect a continuation of the periodic and customary cycles of warmth and cold.

The usual pattern over the last three million years has been the following. After an ice age reaches its coldest point -- when the ice sheets have reached their greatest extent and sea levels have fallen to their lowest -- a period of rapid warming ensues. Global temperatures rise steeply over a period of a few thousand years. Geologically speaking, the ice and snow melt rather quickly. Warmth builds upon warmth -- just as cold can build upon cold -- and carbon levels in the atmosphere rise steadily as biological activity on the planet increases.

Although carbon in the atmosphere is not the only kind of greenhouse gas, we might consider it to be the most significant one when considering impact upon global temperatures. Higher carbon levels in the atmosphere mean more greenhouse retention of warmth, and of course, the inverse is also true.

After reaching a peak of warmth, a somewhat gradual but steady decline in temperature -- punctuated at times by sudden, sharp reductions -- commences. Carbon levels in the atmosphere decrease as the scope of planetary life, which has been the customary source of atmospheric carbon throughout most of geological history, is increasingly limited by the ever-expanding regions of inhospitable cold. The cold begins to perpetuate itself. Ice sheets lead to more ice sheets. Over a period of tens of thousands of years, the global climate finally reaches its nadir of cold, then, the cycle begins anew.

Here below you can see a chart outlining these cycles. Please note that according to this graph the present time is on the extreme left with 400,000 years ago on the extreme right. Note the close correspondence between temperatures and carbon levels.

With regard to carbon levels, there is something of a cause and effect conundrum going on. Do increased carbon levels lead to a greater profusion of biological life and increased global temperatures, does a greater profusion of biological life lead to increased carbon levels and increased global temperatures, or do increased global temperatures lead to a greater profusion of biological life and increased carbon levels? Similarly, do reduced carbon levels lead to a general reduction of biological life and reduced global temperatures, etc.? The answer seems to be yes several times over. The three factors apparently reinforce each other until they reach a critical point.

What about humankind's massive contribution of carbon to the atmosphere? Isn't that an extraneous factor that doesn't follow the normal natural pattern? If so, is it not so decisive as to render the general climate pattern of the last three million years completely inapplicable?

Yes, human activity clearly is an extraneous factor that breaks with the usual long-term climate pattern, which is itself subjected to so many different variables that it is only a rough model at best. But the established cycle has in no way been rendered inapplicable. With regard to the greenhouse gas effect, carbon is basically carbon, whether it comes from purely natural processes or human ones. The eventual descent into all previous ice ages has always been marked by a peak in temperatures and carbon levels.

Apparently, there is some kind of mechanism that "switches" the ice ages off and on at each end of the cycles. It seems that once an extreme of either warmth or cold is reached, something kicks in to head the trend in the opposite direction.

In his documentary film An Inconvenient Truth, Al Gore briefly touches upon this topic by explaining how the continued melting of the Greenland ice sheet will lead to lower salinity levels in the Gulf Stream, which may cause ocean current to change direction. As Gore has pointed out, a similar event several thousand years ago led to a precipitous drop in temperatures and a subsequent resurgence of ice age conditions.

So, we now come to the point of asking ourselves if we as a species have effectively found a way to override or cancel out the switching mechanism.

We are now emitting huge amounts of carbon into the atmosphere by burning coal and oil, among other fuels. Over millions and millions of years, the earth has removed vast quantities of carbon from the atmosphere and stored it through natural processes, and in the span of a century or two, we have released a significant percentage of that stored carbon back into the air. Have we pumped so much carbon into the atmosphere that the earth can no longer reabsorb it?

This is highly unlikely. The earth has experienced many episodes of raised carbon levels in the atmosphere, whether through prolonged outbursts of biological activity or massive volcanic releases of greenhouse gasses, and in every case the carbon levels eventually decreased along with temperatures over a very long period of time. The planet has always been able to eventually reabsorb the excess carbon. True, the carbon levels we are reaching today are for all intents and purposes unprecedented. But lest we forget, similar to a volcanic release of gases, this is not a self-sustaining process, but rather one that must eventually run its course.

Are we capable of continuing to pump carbon into the atmosphere until the end of time? Evidently, we are not. Oil and coal reserves must eventually be exhausted. Even if we chop the top off of every last mountain, strip mine every last inch of land, and sink oil wells into every conceivable part of the globe, there's no postponing the inevitable. There are only so many non-renewable energy sources on this planet. Eventually, we won't be able to pump much more carbon into the atmosphere because we won't have any more oil and coal left to burn. And geologically speaking, that time is approaching very quickly. Actually, we should come upon it in only a few human generations.

Admittedly, before we reach that point, we will have raised the temperature of the atmosphere considerably. Global warming is real and has real consequences. My argument is of course not against the scientific fact of global warming per se, but rather against the idea that human beings will be able to indefinitely sustain our accelerated release of carbon into the atmosphere and that the mechanism that switches on ice ages has been permanently disabled.

In fact, there is evidence to suggest that we may have actually sped up the switching mechanism through our activities and that our next ice age could be arriving considerably ahead of schedule. This is a theme touched upon in the film The Day After Tomorrow, which despite a number of unscientific details -- such as the supposed arrival of a new ice age in a matter of weeks or of air descending from the stratosphere so quickly that it supposedly doesn't have a chance to warm up -- makes a very valid point by showing that human-caused global warming could indeed eventually lead to an alteration of ocean currents that would in turn precipitate a decisive switch to a colder climate.

We do not know when exactly the next ice age will occur. But I think it fairly reasonable to assume that we will reach our peak global temperatures at some point after we have exhausted our non-renewable energy resources. As I have just written, that should take place within a few generations, unless we finally realize earlier that we are operating within a losing paradigm and abandon oil and coal as viable sources of energy.

Regardless, the peak global temperatures will come, our carbon emissions will taper off to lower levels one way or another, and sooner or later, the switching mechanism for initiating the next ice will be turned on.

Geologically speaking, our influence upon the planet's climate will be a rather short chapter in earth's history. Hopefully, distant generations will learn from our mistakes and will minimize their impact upon our thin and delicate atmosphere. Well, with all of the oil and coal gone, they won't really have much of a choice, I suppose.

"Won't you tell me where my country lies?" said the unifaun to his true love's eyes...