COLD, HARD FACTS Franklin Hadley Cocks ’63 visits the grave of Louis Agassiz, the great proponent of the ice age concept.
courtesy of F. H. Cocks
Will the greenhouse effect prevent the return of glaciers?
Global warming is an inescapable issue for our age. But 180 years ago, most scientists believed that Earth had been steadily cooling since it was formed. When Louis Agassiz presented the concept of a Great Ice Age to the Swiss Society of Natural Sciences in 1837, his suggestion that the planet had turned colder and then warmed up again was met with skepticism and even hostility, triggering years of fierce scientific debate before the idea was accepted.
Exactly why our planet occasionally cools down has taken more than a century to work out. Now we know that cyclic gravitational tugs from Jupiter and Saturn periodically elongate Earth's orbit, and this effect combines from time to time with slow changes in the direction and degree of Earth's tilt that are caused by the gravity of our large moon. Consequently, summer sunlight around the poles is reduced, and high-latitude regions such as Alaska, northern Canada, and Siberia turn cold enough to preserve snow year-round. This constant snow cover reflects a great deal of sunlight, cooling things down even more, and a new ice age begins. Naturally, this process does not occur with anything like the speed portrayed in the movie The Day After Tomorrow, but geological and other evidence shows that it's happened at least four times.
With so much attention focused on global warming, this chilly prospect has been all but forgotten. Given how catastrophic another ice age could be, one might be tempted to ask whether a human-caused increase in atmospheric and ocean temperatures will actually be a boon.
There's little question that global warming is happening. Climate data show that Earth's average temperature has risen at least 0.7 oC (1.3 oF) over the 20th century. Temperature increases over the 21st century will probably be two and a half to five times as large,because greenhouse gases like carbon dioxide allow sunlight to penetrate the atmosphere but make it harder for outgoing infrared radiation to escape. What's more, just as carbonated soda fizzes when it warms up, warmer temperatures cause the ocean to release carbon dioxide taken up during colder periods. Analyses of air trapped in glacial ice over the last 800,000 years show that atmospheric carbon dioxide generally ranged between 200 and 300 parts per million by volume (ppmv); increases in these levels were slightly preceded by increases in temperature caused by natural orbital shifts. During this period, global temperature varied by about 12 oC. Now, carbon levels are approaching 400 ppmv as the burning of fossil fuels pumps more and more carbon dioxide into the atmosphere. Even if the rate of growth could be moderated enough to stabilize levels at about 550 ppmv, average temperatures might well rise by about 5 oC--with devastating effects for us earthlings, such as rising sea levels and dramatic changes in weather patterns.
But even that warming will not stave off the eventual return of huge glaciers, because ice ages last for millennia and fossil fuels will not.In about 300 years, all available fossil fuels may well have been consumed.Over the following centuries, excess carbon dioxide will naturally dissolve into the oceans or get trapped by the formation of carbonate minerals. Such processes won't be offset by the industrial emissions we see today, and atmospheric carbon dioxide will slowly decline toward preindustrial levels. In about 2,000 years, when the types of planetary motions that can induce polar cooling start to coincide again, the current warming trend will be a distant memory.
This means that humanity will be hit by a one-two punch the likes of which we have never seen. Nature is as unforgiving to men as it was to dinosaurs; advanced civilization will not survive unless we develop energy sources that curb the carbon emissions heating the planet today and help us fend off the cold when the ice age comes. Solar, nuclear, and other non-fossil-fuel energy sources need to be developed now, before carbon emissions get out of hand. MIT alumni could play a prominent part in discovering the technology needed to keep us all going. And there are fortunes to be made from the effort. It's worth thinking about.
Professor Franklin Hadley Cocks '63, SM '64, ScD '65, teaches energy technology and climate-related courses at Duke University and is the author of Energy Demand and Climate Change (Wiley-VCH), which summarizes energy and climate issues of the past, present, and future.
Averting ice ages is easy; the real problem is avoiding a super-greenhouse world
"Global Warming Vs. the Next Ice Age" seems to make some basic mistakes about how long CO2 sticks around in the atmosphere. Much of the CO2 people are emitting will stick around in the atmosphere for many thousands of years, and its warming effects would persist even longer.
Recent studies by many climate scientists have shown that CO2's effects are extremely long-lasting. If we stopped burning fossil fuels soon, the planet would keep heating up for a few decades. CO2 levels would fall significantly—around half to two-thirds—over the first century.
Yet the temperature would stay basically constant for at least 500 years, and would take a lot more than 2,000 years for the planet to naturally cool back to pre-industrial levels. (See "Irreversible climate change due to carbon dioxide emissions," a 2008 PNAS study led by renowned scientist Susan Solomon, for more details.)
According to research by climate scientist David Archer, we may have already emitted enough CO2 to avert an ice age in a couple thousand years or so. If it weren't for people's CO2 emissions, an additional ice age might kick in sometime in the next 50,000 years—but that may too be averted by our emissions already. And if we burned all the available fossil fuels, we would likely prevent any ice ages from occurring for about half a million years into the future. (For more details, see Chapter 12 of Archer's recent and accessible book, The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate, from Princeton University Press.)
I wrapped up a bunch of the relevant research in an article for Nature Reports Climate Change, "Carbon is Forever".
Basically, if we don't stop burning fossil fuels soon, humanity's going to be in for a difficult time. If we can tackle global warming first, then several centuries down the road we can start worrying about the possibility of another ice age.
Averting an ice age should be relatively easy. We already know how to heat up the planet: just burn fossil fuels. Even if we let free markets run wild and burn up all the fossil fuels that companies and governments can get their hands on, there would remain a fair amount of left in the ground—especially coal and tar sands—that will probably never make sense to dig up. There are some fossil fuel reserves that are deep or dirty, so they take more energy to get out of the ground than they release in burning them, which makes digging them up basically pointless.
So if in some distant age, tens or hundreds of thousands of years from now, CO2 levels and temperatures did fall back toward pre-industrial levels, and we did find ourselves facing the prospect of another ice age, we could dig up some of the remaining coal and tar sands and burn them. It might not have made sense to burn these fossil remains earlier as fuel, because of low return on energy and severe effects on the climate. But if we decarbonize our economy quickly and are still facing the prospect of an ice age in a couple thousand years (or more), perhaps it would eventually make sense to burn some of the remaining coal and tar sands to avoid an ice age, as a kind of climate engineering.
But we could do this slowly, over centuries. It wouldn't call for anything like the all-out fossil fuel burning of the past 60 years. Or perhaps we'll decide that we've done enough monkeying with the climate, and it's better to ride out an ice age rather than try to engineering a way around it.
Overall, averting an ice age seems to be an easy problem compared with tackling global warming and trying to keep people from burning up all the fossil fuels that are relatively easy to get.
(Finally, a shameless plug: If you want to read more of my stuff, check out my website, Failing Gracefully.)
CO2 blocks all 15 micron infrared
This article has ignored an important fact. The fact is that carbon dioxide already absorbs all 15 micron infrared emitted by the Earth. Warming is not caused by CO2. Oceans are, in fact, releasing more CO2 because of temperature rise. Goggle the report "The Lynching of Carbon Dioxide-the Innocent Source of Life", written by Dr. Hertzberg. He is an expert on the CO2 topic.
global climate change Maddnesss
SO: Are we all now on the same page? Do we understand that:.
No matter what We. The human race do, we will not and we cannot change the natural progression of the planets, We cannot Engineer our way into or out of global warming or the next ice age
and it may take another 500.000 years till this happens
Also it will regardless of what taxes are placed on carbon etc,
Are we staving off the next ice age by burning fossil fuel ?
Is there more carbon in the atmosphere now that there was when millions upon millions of ancient forrest were constantly burning in the days before mankind discovered how to make fire. ?
I realise that many scientist and their cohorts in politics can build their careers and make a good living from generation of such hysterical media generation,
Professor Ross Garnaut of Australia is a prime example of the self proclaimed experts who may genuinely believe they are doing the right thing and at the same time they destroy Australian industry and millions of jobs and indeed the australian way of life.
They say that they will reduce carbon use in Australia by 5% while at the same time.
China Which has the worst pollution tonnage in the world will increases their existing
high levels by a further by 15 to 30%..
it would seem the Australian Government were elected on the cast iron promise that there would be NO carbon tax, This labor/Socialist Government, Who it may be be worth mentioning are only in power with the help of a few loopy Self centred independents and the Green party
( who are both morally and intellectually deficit.) Do not have a clue how to run a Country. or an economy.
WE SHOULD ALL BE AWARE THAT THEY WILL SPEND MILLIONS OF TAXPAYERS DOLLARS TO:
Tell the people that rising sea levels will swamp low lying land will be gone in just a few years. or perhaps a hundred years. But what they wont tell you is it will happen and not in our lifetime and all the tax in the world will not stop it or global warming or the next and 5th yes 5th Ice age. it will come in 500.000 years or maybe
2 million years who knows,?
NOBODY! knows and if the truth be told nobody can stop it.
One can only hope the people of Australia will wake up and get rid of them all before the country goes under.
Comment by: GRAYTMIND Qld Australia
Re: global climate change Maddnesss
In 1981 NASA's Dr Hansen made a huge mistake in assuming the Earth's surface radiates like a blackbody. A further assumption was made that radiation from a colder atmosphere can be converted to thermal energy by a significantly warmer surface. It cannot be, and so it cannot warm or slow the rate of cooling. See http://climate-change-theory.com for more detail.
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durs
44 Comments
OMG
This has got to be the stupidest drivel I've hear in a long time.
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edv
1 Comment
Re: OMG
At last an explanation of why there is a long history of an increase in CO2 approximately 50 years *after* an increase in atmospheric temperature. It is too bad that global warming advocates find this to be such a threat, even though it does not preclude the possibility of increases in temperature due *to* CO2 rise as well. This is the kind of thinking which has caused fudging of data to reinforce current global warming theories. Of course, this tactic has the unintended consequence of *weakening* the argument.
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