Global Warming/New Ice Age Nonsense. A Hollywood movie, The Day After Tomorrow, debuted this weekend. It posits catastrophic and sudden climate change, including a new Ice Age, produced by global warming. That's right: global warming might produce a new Ice Age. Climatologist Tom Prugh, interviewed by National Geographic News in a story hilited on AOL today, says there's "a kernel of truth" in the premise.
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I have followed the "global warming" craziness for years, and read some weeks ago the nonsense that seems to underlie the movie, that global warming might cause the Gulf Stream to stop flowing, which could plunge northern latitudes into a new Ice Age, with average temperatures dropping as much as 20 or more degrees Fahrenheit almost suddenly, and in only a few years from now. Yes, we really are supposed to believe that global warming can cause a new Ice Age, and soon! Let's be clear here: warming does not produce cooling, certainly not short-cycle.
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One theory about how warming could cause an Ice Age is that if the Arctic Ocean doesn't freeze solidly over, its exposed surface would produce much higher snowfalls all around it, much as open water on the Great Lakes produces high "lake-effect" snowfalls. Evaporation would tend to make the remaining Arctic water saltier, which would keep it open water longer. Meanwhile, snows all over the lands around it would accumulate higher and higher, reflect massive amounts of sunlite for most of the year, and gradually produce ice sheets such that even after the Arctic Ocean froze over because the temperature year-round was by then cold enuf, it would be too late to reverse the self-sustaining accumulation of ice, and a new Ice Age would creep down from the pole, burying everything under a mile of ice. But this could happen only if the astronomical conditions for an Ice Age were also in place.
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There is no such thing as global warming produced by human activity. We are between Ice Ages, so of course we're warmer now than 11,000 or 20,000 years ago. Scientists can't even agree on how much the Earth has warmed in the past 100 years or how much it might warm in the next 100. Some say it's warmer by one whole degree Fahrenheit and might rise another 2 degrees in the next fifty years! Passing over, for the sake or argument, the possibility that a tiny discrepancy between the accuracy of thermometers 100 years ago and now could explain away the entire phenomenon, let's consider if an increase of even 6 degrees Fahrenheit would make a damned bit of difference in climate change.
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Water freezes at 32 degrees Fahrenheit. It also melts at 32 degrees - tricky business, that; it depends on whether heat is being taken away or added. The warmer the surrounding temperature, the faster ice melts, which also means the greater the quantity of ice that melts. But 1 degree or 6 degrees' change in temperature is not going to do much of anything to the rate of melting presently experienced. The high Arctic rarely gets much above 60 degrees, and freezing temperatures occur every single month. Yellowknife, Northwest Territories' 'hottest' month, July, averages 69 degrees, even tho the sun never sets from early May to the beginning of August. Yellowknife has only 50 days above 65 degrees, as against 224 below freezing.
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Extended periods below -20 F are common in much of the Arctic, and temperatures of -40 and -50 are commonplace. How is a difference of 6 degrees going to accomplish anything? Minus 14 is going to keep ice frozen just as well as -20! Moreover, 32 is not the coldest ice gets. If the atmosphere adjoining ice cools to -20, some portion of the ice itself will also cool to -20. That means it has to be warmed up to 32 before it even begins to melt. That might take a while. One warm day isn't going to do it.
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Here in New Jersey temperatures vary from about 0 to 102 degrees Fahrenheit. Who cares about a change of 1-3 or even 6 degrees? We often have temperature differences of more than 20 degrees in the same day.
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Scientists can't agree on how long it will be before the next Ice Age arrives, or even if there will ever be another Ice Age, given human activity flooding the atmosphere with "greenhouse gases". Is the period between Ice Ages about 10,000 years long, in which case we're due for another within a couple of thousand years? Or might more "greenhouse gases" stave it off for 10,000 or 60,000 or 100,000 years? No one knows.
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What we do know is that the Ice Ages were produced not by anything on Earth itself but were "caused by slow, periodic changes in the shape and position of the Earth's orbit around the Sun". They are also affected by whether the Northern Hemisphere is tilted toward or away from the sun at our closest approach to that ultimate heat source. Now, we are closest to the sun in January, which means that winter in the Northern Hemisphere is milder than it was 11,000 years ago (during the last Ice Age), when we were closest to the sun in July, which meant that northern summers were hotter but northern winters occurred when we were farthest from the sun, which made them colder.
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Although the largest ice sheet is over the South Pole, because there is land there, it cannot extend too far outward because of open ocean almost everywhere around it save the narrow tip of triangular South America. The Ice Ages affected the Northern Hemisphere more severely because altho the North Pole itself is in water, the Arctic Ocean is small, and almost the entire circumpolar region is solid land for thousands of miles outward. Land doesn't have currents to carry away cold and bring warmth, so ice doesn't thin or break up over land nearly so fast as it does over water (especially sea water, which contains salt). Moreover, the Northern Hemisphere, the Land Hemisphere (most of the planet's land surface is north of the equator), is where most people live, so the growth of ice caps is, to people, much more important in the Northern Hemisphere than the Southern.
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Nature magazine's website says, "Although ice ages are ultimately caused by orbital changes, they seem to rely on feedbacks within the Earth's climate system. The ice sheets provide such a feedback - the bigger they get, the more sunlight and heat they reflect, and so the more the Earth cools." But this is a very gradual process. It doesn't occur overnite or over a few short years.
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What else reflects sunlite? Clouds. What produces clouds? Evaporation. What produces evaporation? Heat. So the system is in part self-regulating, even without biological activity, much less human activity. 71% of Earth's surface is covered by water, which means that most of what is heated by the sun is water. More heat, more evaporation, more clouds, more reflection of sunlite out into space - which reduces the amount of heat reaching the surface.
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Moreover, Earth supports huge amounts of plant life, much of it in the oceans in the form of algae. Tho deforestation is occurring in parts of the Third World, the forests of the First World are actually thriving, and expanding. In North America, for instance, areas that a century or two ago were cleared for farming in New England and for timber in Upstate New York are now covered in forests again. Even urban sprawl has meant reforestation in the sense that farmland, which is mainly treeless and thus relatively underutilized in a biological sense, and over the winter is basically devoid of vegetation, is replaced by houses around which are planted trees, including evergreens, which perform photosynthesis whenever the temperature rises above about 45 degrees. Older suburbs become the equivalent of forests interspersed with meadows, which absorb a lot more carbon dioxide than do seasonal farms.
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So, the warmer the climate, the longer the growing season, the more trees and algae thrive, the more carbon dioxide they take out of the atmosphere, so again there is a brake on warming. Snails and sea creatures that form shells take carbon dioxide and make calcium carbonate from it, which takes carbon dioxide out of the atmosphere for very long periods. Some is pretty much permanently removed, as limestone.
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Conversely, when temperatures are lower, the growing season is shorter, and less carbon dioxide is removed from the atmosphere, leaving more of this "greenhouse" gas to limit cooling.
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This biological regulation of atmospheric gases and thus moderation of climate was first appreciated in 1965 by James Lovelock, a British scientist working with NASA. His neighbor in Wiltshire, the Nobel prize-winning British author William Golding, suggested for this concept the name of the first Greek goddess, 'Mother Earth', who emerged from Chaos and gave order to the Earth. In the late 1960s, Lovelock formulated "The Gaia Theory" and published his first article on it in 1972.
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This theory predicts that climatological changes produced by changes in the chemistry of the atmosphere (not those produced by changes in Earth's orbit) will be moderated by life: cooler temperatures result in more carbon dioxide, which limits cooling; warmer temperatures result in more carbon dioxide being taken out of the atmosphere by living beings, which limits heating.
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Thus, we could have catastrophic global warming, with its unpredictable consequences, only if we destroyed a very large portion of the world's algae AND forests at the same time. We're not doing that.
- posted by L. Craig Schoonmaker @ 11:53 PM