August 06, 2009
Earth Rotational Periods Cause Ice Ages And Warmings

Changes in how large planets such as Jupiter and Saturn pull at the Earth's rotation cause the Earth to go into periodic cooling and warming periods.

CORVALLIS, Ore. Researchers have largely put to rest a long debate on the underlying mechanism that has caused periodic ice ages on Earth for the past 2.5 million years they are ultimately linked to slight shifts in solar radiation caused by predictable changes in Earth's rotation and axis.

In a publication to be released Friday in the journal Science, researchers from Oregon State University and other institutions conclude that the known wobbles in Earth's rotation caused global ice levels to reach their peak about 26,000 years ago, stabilize for 7,000 years and then begin melting 19,000 years ago, eventually bringing to an end the last ice age.

The melting was first caused by more solar radiation, not changes in carbon dioxide levels or ocean temperatures, as some scientists have suggested in recent years.

"Solar radiation was the trigger that started the ice melting, that's now pretty certain," said Peter Clark, a professor of geosciences at OSU. "There were also changes in atmospheric carbon dioxide levels and ocean circulation, but those happened later and amplified a process that had already begun."

Solar radiation changes rather than carbon dioxide (CO2) concentration changes initiated recent ice ages and warmings. So then is CO2 causing warming now?

A lot of people hope that carbon dioxide emissions do not cause global warming. I say they are making an error in how they look at the problem. Since changes in the Earth's orientation are driving us toward a cooling period all that coal and oil we burned might be all that is holding off another ice age. So I hope CO2 warms up the planet.

Sometime around now, scientists say, the Earth should be changing from a long interglacial period that has lasted the past 10,000 years and shifting back towards conditions that will ultimately lead to another ice age unless some other forces stop or slow it. But these are processes that literally move with glacial slowness, and due to greenhouse gas emissions the Earth has already warmed as much in about the past 200 years as it ordinarily might in several thousand years, Clark said.

If CO2 is causing warming we probably ought to stop burning fossil fuels and instead reserve their burning for the future period when the solar radiation drops enough to cause an ice age.

Share |      Randall Parker, 2009 August 06 10:05 PM  Climate Trends


Comments
"The Other" Grim said at August 6, 2009 10:56 PM:

The CO2 levels used to be much higher than today (something on the order of 10x as much). If that did not prevent ice ages I don't think anything we produce can.

Paul said at August 7, 2009 5:19 AM:

If a change in solar radiation in the past started ice ages, that does not imply a change in CO2 cannot affect global climate.

Similarly, the fact that shooting yourself in the head with a shotgun can kill you does not not imply jumping off a 100 story building is safe.

"The Other" Grim said at August 7, 2009 8:41 AM:

Paul, I believe you missed my point: CO2 does not seem to be able to stop ice ages. Wither it cause slight variations on warming is immaterial to that issue. We need something stronger top stop an ice age. In the long run finding controls that stop ice ages is one of the most important things the human race can do.

Look at it this way: 4C increase in the next 100 years = loosing lots of productive areas to desert/water. But we gain places like Northern Canada and Siberia to expand into.
Ice Age = loosing 40% of our productive land and gaining a small amount low lying formerly under water land/a few deserts. Ice ages are much worse for the future of humanity.

Or maybe I am wrong and both would open good areas for humanity?

Wolf-Dog said at August 7, 2009 11:40 AM:

However silly, the new movie 2012 about the end of the world, capitalized on the related theory that somehow external events in the solar system, such as changes in the sun, can cause the poles of the planet Earth to reverse abruptly, causing major earthquakes and tsunamis powerful enough to destroy civilization.

JAY said at August 7, 2009 6:18 PM:

Every warming was caused by humans driving SUVs. The IPCC already proved it.

simone said at August 8, 2009 9:22 AM:

Your last line makes me wonder if you are just trying to tweak all of us because it has nothing to do with scientific reasoning.

Randall Parker said at August 8, 2009 9:36 AM:

simone,

Online communication is difficult at best because we can't immediately ask a person what they mean and we do not necessarily remember what other people have said on various subjects. My views are more visible than yours since I write this blog. So I gotta ask you: Are you implying that the theory of anthropogenic global warming (AGW) is bullshit and therefore saving fossil fuels to prevent warming later is not going to work?

Or are you saying something else?

Once you make your position clear I'll respond about my last line.

Randall Parker said at August 8, 2009 11:38 AM:

"The Other" Grim,

When did the Earth have an ice age while CO2 was 10 times current levels? Got a link to a scientific source for this assertion?

As for the possibility that CO2 wouldn't be enough to prevent an ice age: Depends on how much solar radiation drops. But suppose CO2 wasn't enough. We have other gases at our disposal. For example, we could make methane using nuclear reactors or photovoltaics to power the synthesis of methane. Or we could generate chloroflourocarbons (CFCs).

But if we really want to heat up the place then one gas stands out: Sulfur Hexafluoride (SF6) has 23,900 times the warming potential of CO2.

rsilvetz said at August 8, 2009 11:54 AM:

Geez, look at that... Now how many times have I posted this exact info right here -- that nutation and precession of the Earth in its orbit -- are the primary determinants of temp? Can we now stop the Global Warming Hysteria (tm)?

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