February 10, 2009
Save Fossil Fuels To Use To Delay Next Ice Age?

We should use more nuclear, wind, solar, and geothermal power now so we can save fossil fuels to use later to delay the next ice age.

Professor Shaffer made long projections over the next 500,000 years with the DCESS Earth System Model to calculate the evolution of atmospheric CO2 for different fossil fuel emission strategies. He also used results of a coupled climate-ice sheet model for the dependency on atmospheric CO2 of critical summer solar radiation at high northern latitudes for an ice age onset.

The results show global warming of almost 5 degrees Celsius above present for a "business as usual" scenario whereby all 5000 billion tons of fossil fuel carbon in accessible reserves are burned within the next few centuries. In this scenario the onset of next ice age was postponed to about 170,000 years from now.

Carbon can postpone ice age

However, for a management scenario whereby fossil fuel use was reduced globally by 20% in 2020 and 60% in 2050 (compared to 1990 levels), maximum global warming was less than one degree Celsius above present. Similar reductions in fossil fuel use have been proposed by various countries like Germany and Great Britain.

In this scenario, combustion pulses of large remaining fossil fuel reserves were then tailored to raise atmospheric CO2 content high and long enough to parry forcing of ice age onsets by summer radiation minima as long as possible. In this way our present equable interglacial climate was extended for about 500,000 years, three times as long as in the "business as usual" case.

Sounds like a good idea to me. Though we could always use nuclear fusion reactions to drive synthetic production of methane for a much more powerful greenhouse gas.

In any case, we've already kicked the next ice age 55,000 years into the future. So we've got that going for us. Which is nice.

"It appears to be well established that the strong ice ages the Earth has experienced over the past million years were ushered in by declining levels of atmospheric CO2. Our present atmospheric CO2 level of about 385 parts per million is already higher than before the transition to these ice ages" Professor Shaffer notes and adds that "The Earth's orbit is nearly circular at present meaning that the present minimum in summer radiation at high northern latitudes is not very deep. We have already increased atmospheric CO2 enough to keep us out of the next ice age for at least the next 55,000 years for this orbital setup".

Share |      Randall Parker, 2009 February 10 10:55 PM  Climate Engineering

Engineer-Poet said at February 11, 2009 8:46 PM:

We wouldn't need fossil fuels.  There is an enormous amount of carbon tied up in limestones and methane hydrates that we could liberate to keep the climate from tipping to a cold state if we needed to, and these things reform much more easily than coal, oil and gas.  Every few tens of thousands of years we could shift the economy from using atmospheric carbon to some measure of sequestered carbon and back, and keep the temperature more or less even.

Paul F. Dietz said at February 12, 2009 5:10 AM:

Perfluorocarbon gases are probably much better than CO2 for deliberately increasing atmospheric IR opacity. CO2's absorption bands are already well covered, so additional gas has a relatively weak effect, compared to gases covering virgin parts of the spectrum. PFCs can also be longer lived in the atmosphere, and do not acidify the oceans.

Jag Fulvit said at February 12, 2009 2:41 PM:

This is the absurd cargo cult thinking that is making Al Gore a billionaire.


David Friedman said at February 13, 2009 12:55 AM:

I think concern about whether the next ice age starts in 170,000 years or 500,000 years, while entertaining, is essentially pointless. Given the current rate of technological progress, the world of even two or three centuries in the future is almost entirely unpredictable. We might wipe ourselves out, we might all upload to silicon, we might be spending our time in VR with minimal consumption of physical goods, ... . It is extraordinarily unlikely that we will still be getting from one place to another in automobiles powered by internal combustion, and not very likely that we will be heating our houses by burning coal, gas and oil.

Stretch that out past 100,000 and you might as well be talking about a neanderthal estimating the global problems of the 21st century and what to do about them.

happyfeet said at February 13, 2009 7:29 AM:
"Fossil fuel reserves may be too valuable for regulating climate far into the future to allow the reserves to be consumed within the next few centuries. The price of extreme global warming to avoid ice ages is a high and indeed unnecessary price to pay."

For this to be workable, you'd have to believe that the cult of global warming will have died a well-deserved death by the time we needed to carbon up. Here's a rock solid prediction... 170,000 years from global warming will be earth's largest established religion and the very idea of purposely releasing sinful carbon dioxide molecules will be anathema and to even suggest it, blasphemy. And poor naive Professor Shaffer's work will have all been burned and forgotten long long ago.

Engineers Doet said at February 13, 2009 7:52 AM:

We are learning to make all types of hydrocarbon fuels from microbes and biomass. How stupid is it to sanctify hydrocarbons lying deep within the ground when more industrialists every day are learning to make the same hydrocarbons in the full light of day?

Pat said at February 13, 2009 7:58 AM:

The idea assumes that CO2 actually heats up the atmosphere. Would 10 times more CO2 do anything to global temperatures? The long-term climate record of planet Earth suggest that CO2 is not a factor.

According to this report:

"There has historically been much more CO2 in our atmosphere than exists today. For example, during the Jurassic Period (200 mya), average CO2 concentrations were about 1800 ppm or about 4.7 times higher than today. The highest concentrations of CO2 during all of the Paleozoic Era occurred during the Cambrian Period, nearly 7000 ppm -- about 18 times higher than today.

The Carboniferous Period and the Ordovician Period were the only geological periods during the Paleozoic Era when global temperatures were as low as they are today. To the consternation of global warming proponents, the Late Ordovician Period was also an Ice Age while at the same time CO2 concentrations then were nearly 12 times higher than today-- 4400 ppm. According to greenhouse theory, Earth should have been exceedingly hot. Instead, global temperatures were no warmer than today. Clearly, other factors besides atmospheric carbon influence earth temperatures and global warming."

Shannon Love said at February 13, 2009 8:07 AM:

"It appears to be well established that the strong ice ages the Earth has experienced over the past million years were ushered in by declining levels of atmospheric CO2.

This is incorrect. Evidence from ice core samples shows that CO2 is a trailing indicator of warming and cooling during ice ages. As the planet cools, CO2 is interred in frozen biomatter and solvated into the oceans. When the planet warms again. The CO2 is released. Ice ages are caused by the precession of earth's axis that subtly alters the heat distribution on the oceans and continents.

There is a feedback cycle with CO2 that amplifies both cooling and warming but changes in CO2 do not initiate the changes.

Alec Rawls said at February 13, 2009 11:34 AM:

Wrong. What is needed to be able to stop the next ice age from descending is technological progress, which in turn is a function of prosperity. We need to do what is economically efficient today so that we can keep making the technological progress to ward off not just the next ice age, but all the other looming threats, astroidal, biological, Islamofascist, etcetera.

My technological prediction? Massive sun reflectors, directing additional sunlight to planet earth.

RebeccaH said at February 13, 2009 11:53 AM:

If it is at all possible to fend off an Ice Age (which I think is highly unlikely), it won't be by burning fossil fuels. In any case, thousands of years into the future, we will have colonies in space and our cities will be so technologically advanced that a mere Ice Age would be a negligible nuisance, nothing more.

Randall Parker said at February 13, 2009 6:22 PM:

David Friedman,

Yes, I agree. 100 years from now I doubt our replacements (be they robotic, cyborg, or genetically engineered, or nanotech goo organisms) will need fossil fuels for climate engineering.

But I wrote this post because it entertains me to think about using fossil fuels for climate engineering.


Why do think we won't be able to fend off an ice age? We will have lots of ways to do it:

1) Our space colonists could construct reflector satellites that will aim more sunlight at Earth.

2) We could darken portions of the Earth by painting buildings and highways black. They would absorb more light and give off more heat.

3) We could make desert areas darker. Easy enough to do with sufficiently advanced tech. Again, will absorb more light.

4) We could generate methane or, as Paul F. Dietz recommends, perflourocarbons to warm things up.

Randall Parker said at February 13, 2009 10:14 PM:


Maybe I misread you and you are really saying an ice age is what is unlikely? Well, certainly unlikely in the short term. But in the scale of tens or hundreds of thousands of years ice ages become likely. At least they become likely absent human or robotic intervention.

th said at February 14, 2009 7:03 AM:

Greenhouses heat from convected heated air, not this new age nonsense about IR light. A polished rock salt greenhouse that allows IR to pass freely out traps heat as well as one made of 12 inch thick glass or thin sheet plastic, R-values being the only variable that matters.

Ken said at February 15, 2009 5:35 PM:

I think that, given the best scientific understanding of the severe consequences of rapidly increasing GHG concentrations, a comment like "In any case, we've already kicked the next ice age 55,000 years into the future. So we've got that going for us. Which is nice..." is at all appropriate. It appears to be trivialising the enormous changes to our climate that are occurring now.

Randall Parker said at February 15, 2009 5:49 PM:


An ice age is worse than a big melting. There are benefits from the CO2 build-up. That's one of them.

Also, I was slightly paraphrasing Bill Murray from Caddy Shack at the end of his Dalai Lama speech while holding a pitch fork at the kid's throat.

Ken said at February 16, 2009 8:12 PM:

Randall, are you serious? The consequences of AGW are that we're benefiting from a massive build up of GHG's? But then you've never really taken AGW seriously.

Randall Parker said at February 17, 2009 8:28 PM:


Am I serious? I just told you that I'm quoting Bill Murray from Caddy Shack. Moral posturing is wasted on me.

I told you we are benefiting from a delay in an eventual Ice Age. Granted that Ice Age might not come for thousands of years even if we'd stopped burning fossil fuels 20 years ago. So the benefit seems slight. See what I said above when I agreed with David Friedman.

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