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The Planet Earth blog

'Greenhouse gases could have caused an ice age'

Owen Gaffney

On Monday we reported on a piece of research funded by NERC and published in the journal Science. The work confirms earlier predictions that the Snowball Earth theory - that ice sheets probably stretched down to the equator during some periods of Earth's history - could coexist with high levels of greenhouse gases in the atmosphere.

To some this seems to contradict all that's reported in the press about greenhouse gases and rising temperatures: more greenhouse gases equals more heat. Indeed when the Daily Telegraph originally reported the story (3 January) it said, 'Greenhouse gases could have caused an ice age, claim scientists. Filling the atmosphere with Greenhouse gases associated with global warming could push the planet into a new ice age, scientists have warned.'

The article has generated 65 comments to date, all entirely understandable. Here are a few from Monday:

'So, CO2 causes both global warming and global cooling? Could it be that these two effects cancel each other? Or could it be that the warming theory is falling apart and they need research funds so badly, that they will say ANYTHING to justify more research (money).'

'You "scientists" dont have a clue what is really going to happen. yawn.....'

'First they say Global Warming is caused by CO2, now they are saying Global Cooling is caused by CO2. Which is it?'

One of the paper's authors, Professor Ian Fairchild from the University of Birmingham, was rightly concerned about how his paper has been reported. He had written to the Telegraph who eventually responded (on Monday coincidentally) - the journalist said he would correct the text. Yesterday they made the changes. The headline now reads, 'Ice age atmosphere was 'warm', claim scientists.'

The research paper, and its accompanying press release, don't say greenhouse gases caused the ice age. Indeed, the original deep freeze may have been prompted by a drop in greenhouse gases. Earth at the time - 630 million years ago - was very different from today, not least because the sun radiated less heat. And the ocean and atmospheric circulations that distribute heat from the equator towards the poles would be significantly less effective with ice covering the planet - have a look at our article for a full explanation.

The reporting highlights the problems of communicating climate science and has sparked heated debates on the Telegraph and Ben Goldacre's Bad Science websites.

Goldacre raises an interesting point: 'People in the "public engagement" community often talk about how scientists should do more to communicate with the media. I take a different line: scientists have good grounds to be extremely nervous, and some entities and journalists could quite fairly be blacklisted.'

Over a year ago I questioned a journalist at the paper about how it reported and commented on climate science. He said the then editor did not believe the evidence presented by the climate research community.

This article, along with Christopher Booker's recent opinion pieces left me wondering if the Telegraph still held the same editorial view. Yesterday I spoke to the Telegraph's environment correspondent, Louise Gray, who did not write the article in question, to find out. Gray says the Telegraph's line on climate science is pragmatic. 'Scientists and world leaders accept that climate change is a major challenge and we don't disagree with that viewpoint. But the response needs to be balanced and proportionate. We think it is right to question everything. It is legitimate to ask questions and to show another viewpoint. This opens up debate.'

No one would disagree with that. The article has stirred a debate.

Posted on 13 January 2009

Your comments

An important part of the science connected with this issue is that water vapour is a powerful greenhouse gas and if levels of it are lower (in a Snowball earth) one has to factor that into how large the overall greenhouse effect would be. So the warming contribution from any increase in carbon dioxide has to be added to a cooling contribution from a reduction in water vapour to get the net effect.

Alan Thorpe, NERC
Wednesday, 14 January 2009 - 15:58

I've read so many articles on this greenhouse effet.I may be a simple man but I looked at a simple process that goes on in every household - making cold and ice in a refrigerator.The process is simple; heated ammonia vaporizes in one half of the cycle, it condenses in the other, reducing temperature and freezing water. Vaporize and condense.On a large scale, the planets processes half of a cycle being warming,(green house gases), condensing, cold and ice formation.The planet must heat up, via gases, then condense, cooling down.This is a continual process, cycling elements from inorganic to organic forms, from magma to gases to humic substances found on the surface, to micrtobes in water; the planet is completely alive and continualy recycling everything through their cycles.Within the vaccum, negative pressure of space, there is atmosphere, then liquids, then solid matter-this is the same environment you find in a vacuum flask putting whatever though changes via temperature.

Larry Corliss, Adelanto, Calif.
Tuesday, 1 September 2009 - 02:16

This article and its links do not really give a clear idea of the research. However, another story has more information and links to the paper in Science.

What noone seems to realise is that far from it being amazing that high leves of CO2 co-existed with Snowball Earth, those high levels were needed to get the Earth out of Snowball Earth. The most likely scenario is Snowball Earth began when CO2 levels fell. The continents and the mountains were arranged such that ice sheets formed cooling the planet and causing more ice sheets. This positive ice-albedo feedback led to a runaway cooling and a Snowball Earth. There was also a positive feedback from water vapour decreasing as the temperature fell and so caused more cooling.


Alastair B. McDonald, Wimborne
Thursday, 14 January 2010 - 14:58

(continued from previous comment)

The only way out of Snowball Earth was for CO2 levels to increase, due to volcanic eruptions, to a level where they melted the sea ice, and so raised water vapour density, which then ran away due to its positive feedback effect, now operating in the opposite direction. The catastrophic melting is recorded in the Great Breccia, Port Askaig Formation, Scotland.

It is not amazing that high levels of CO2 existed during Snowball Earth, they were needed in order to end it.

Alastair B. McDonald, Wimborne
Thursday, 14 January 2010 - 15:20


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