Study: ‘Virtually’ Certain Impact of Manmade ‘Climate Change is Observable in Arctic Sea Ice Already Today’

Joe Romm
Think Progress / Investigation
Published: Sunday 6 May 2012
When scientists try to attribute some observed climatic change to a specific forcing, they usually use complex climate models.
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The ongoing rapid retreat of Arctic sea ice is often interpreted as the canary in the mine for anthropogenic climate change. In a new study, scientists have now systematically examined the validity of this claim. They find that neither natural fluctuations nor self-acceleration can explain the observed Arctic sea-ice retreat. Instead, the recent evolution of Arctic sea ice shows a strong, physically plausible correlation with the increasing greenhouse gas concentration. For Antarctic sea ice, no such link is found – for a good reason.

When scientists try to attribute some observed climatic change to a specific forcing, they usually use complex climate models. The scientists at Germany’s Max Planck Institute for Meteorology (MPI-M), however, decided on a different strategy as they set out to identify the main driver for the observed sea-ice loss in the Arctic. Dirk Notz, lead author of the study that was now published in the journal Geophysical Research Letters [1], explains why: “Sea ice is so thin that it reacts very sensitive to the large natural fluctuations of weather and climate that prevail in the Arctic. Because these fluctuations are inherently chaotic, their specific timing cannot be reproduced by standard climate models. Such models therefore aren’t necessarily the best tool to examine if natural fluctuations did cause the observed sea-ice loss.”

The scientists instead used a historical record that described the natural variations of sea-ice extent between the early 1950s and late 1970s. These natural fluctuations were then compared to the magnitude of fluctuations of the Arctic sea-ice cover as measured from satellites since the late 1970s. From such comparison, the scientists found only a minute chance that the recently observed extreme sea-ice minima simply happened by chance – and they could exclude self-acceleration as the main driver for the observed sea-ice retreat. “Whenever we had a strong sea-ice loss from one year to the next, the ice cover always recovered somewhat in the following year,” explains Dirk Notz. This would not be the case if the sea-ice retreat were indeed self-accelerating.

Jochem Marotzke, Director at MPI-M and co-author of the study, describes what the scientists did next: “Having excluded natural fluctuations and self acceleration as the main driver for the sea-ice retreat, it was clear to us that some external driver was responsible for the observed sea-ice decline. We therefore set out to find an external driver that showed a physically plausible relationship with the observed sea-ice retreat.” The scientists examined, for example, the strength of solar radiation. “Here, a physically plausible link to the observed sea-ice retreat can only be established if solar radiation had increased in recent years.” However, solar radiation has slightly decreased in the past decades. Its fluctuations are therefore very unlikely to be the main driver of the observed sea ice loss. The scientists could not find a plausible link to changes in prevailing wind patterns, volcanic eruptions, oceanic heat transport, or cosmic rays, either.

“In the end, only the increase in greenhouse gas concentration showed a physically plausible link with the observed sea-ice retreat. We expect a decreasing sea-ice cover for increasing greenhouse gas concentration, which is exactly what is observed,” Notz explains. The physical link between greenhouse gas concentration and sea ice is quite straightforward, he adds: “Greenhouse gases increase the down welling thermal radiation. This radiation, in turn, is the major player in the heat budget of Arctic sea ice.”

In the Antarctic, the situation is different. Here, the sea-ice cover is slightly increasing. This increase is clearly incompatible with greenhouse gas concentration being the main driver for the sea-ice evolution down South. The major reason for this discrepancy lies in the different landmass distributions, the scientists find. In the Arctic Ocean, the ice is virtually locked by the surrounding landmasses, and its extent is primarily governed by its melting and freezing. Therefore, greenhouse gases play such an important role up in the high North. In the Antarctic, by contrast, the sea ice is free to drift around in the open Southern Ocean. Hence, the ice extent there is primarily governed by the prevailing wind patterns. “Our results show that greenhouse gas concentration is currently not a major driver for sea-ice extent in the Southern Ocean, where winds and currents clearly are more important,” explains Marotzke. “In the land-locked Arctic Ocean, however, greenhouse gas concentration appears to play the dominating role for the observed sea-ice evolution”.

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ABOUT Joe Romm

Joe Romm is a Fellow at American Progress and is the editor of Climate Progress, which New York Times columnist Tom Friedman called "the indispensable blog" and Time magazine named one of the 25 “Best Blogs of 2010.″ In 2009, Rolling Stone put Romm #88 on its list of 100 “people who are reinventing America.” Time named him a “Hero of the Environment″ and “The Web’s most influential climate-change blogger.” Romm was acting assistant secretary of energy for energy efficiency and renewable energy in 1997, where he oversaw $1 billion in R&D, demonstration, and deployment of low-carbon technology. He is a Senior Fellow at American Progress and holds a Ph.D. in physics from MIT.

If a paradigm enters into a

If a paradigm enters into a species such as man, then participation in the issues that bring about change is key to how the debate, or the zeitgeist is formed. This is the most important point in the history of humanity and we are proving ourselves to be ignorant in the collective sense, or participatory sense as that relates to learning and structural coupling, indicating an awareness of, essentially, spherical relationships in ecology. Getting back to the debate, however, considering James Lovelock and his May lecture of 2011 where there should be argument about how to turn the thermostat on the planet lower and this is a beginning (as is Hurricane Erin on 9/11 a similar primer for the application of, and..., for hope - from Alex Jones). Certainly, CIHT technology as well the the Grand Unified Theory of Classical Physics should be applied, presented, and debated from all the angles, which are many it can be introduced from. Possibly, Mills should have to take pennies on the dollar for the insane profits he stands to make, but, is paving the way for. Likely, the criminals will not be outbid in the end, and will apprehend this profit motive to wholesale the intellect of the human race for.

There is soooo much more. Do not ignore Lovelock. Covert, however, begins with the drug cartels and money laundering. Google Indira Singh Guns and Butter from back in 2005. Know James Bamford, William Binney, and Thomas Tamm. A second grader (an intelligent one) could program what the drug cartels are getting away with. The psychology is explained by Gregory Bateson's Steps to an Ecology of Mind.

I read recently that around

I read recently that around 16000 scientists had signed a petition claiming that our carbon emissions were not the main reason for climate change. It would appear that íncreased underwater volacanic activity is also playing a role and that other planets are also experiencing warming. While the claim that it is greenhouse gases seems very credible it would be interesting to see some research evaluating the role of non greenhouse gas factors. I have the feeling this article may have over simplified the issue.

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Mr. Ziolkowski is right on,

Mr. Ziolkowski is right on, and it's worse than most think.... since 2009 in Copenhagen, nearly the whole world has been willing to act on CO2 dosing of the air, but American Republicans have blocked the way! So, what do we do about this half of America that is sluicing the world down the drain to death? This is where leftists and environmentalists need to wise up a little....our elections and poiliticians are mostly honest and NOT bought and paid for by Wall Street nor corporations. What happens is that the voters all watch television, and they THINK that if anything were wrong with the environment, television WOULD TELL them! Oh, wrongo, activists, TV conceals the problems, conceals the solution (Solar Panels), and reassures the loyal Republicans and center-right that everything is OK! Re-direct, activists, Occupy Hollywood and Burbank in Los Angeles and get the word out to these TV-hypnotized Republicans and swing voters how bad the problem is. Until the motion imagery media gets into action, we will be in a bad way! Pretty soon, TV ignoring the problems (like ocean acidification) will force the public to concede that the movie and television industry is a law unto itself, dedicated to evil, and bent on steering the population towards death. Do something about the way the media works in this country, and presto: PROBLEM SOLVED!

There is no doubt as to the

There is no doubt as to the validity of these comments. We have been hearing this for many years. Nobody's listening! The nations bordering on the Artic Ocean are talking about constructing shipping ports. The date when the Artic Sea Ice finally disappears is a source of betting pools. The rising sea levels are measurable and the changing climate conditions become more evident each year. Nobody is listening! And this is one event they can't "fix" with a few laws and a bunch of money at the last moment. Will the last person out please turn off the lights.

What the heck is wrong with

What the heck is wrong with those scientists (said dripping with sarcasm)?? Don't they know they don't need to check it out? The deniers have already decided how it is and they don't need to be burdened with no stinkin' facts or proof. See, you all just don't get it. They just KNOW it's a natural phenomenon and that's all there is to it. Just ask them. They'll set you right. Science not required.For other examples see: George W. Bush and Weapons of Mass Destruction. Many other examples available.

It's good to hear yet again

It's good to hear yet again proof of our harmful impact on the climate, but sometimes words are not enough.
If you want to observe the effects of climate change with your own eyes, please make every effort to see the soon-to-be-released documentary "Chasing Ice" (
It follows the work of renowned National Geographic photographer, James Balog, who since 2007 has devoted his life to recording the massive melting of glaciers and ice shelves from Iceland to Alaska. The time-lapse videos he's produced are breathtaking in their beauty, but no less horrifying for all that.
These glaciers are "canaries" in the coal mine of climate change on Spaceship Earth.
We ignore their demise at the peril of our own.


CONSERVATIVES, REPUBLICANS, TEA-PARTY members and BLUE DOG DEMOCRATS are not capable of recognizing Good Science or admiting what the average Individual can see with their own eyes, or speaking the TRUTH about anything to do with the Environment.

If CONSERVATIVES, REPUBLICANS, TEA-PARTY members and BLUE DOG DEMOCRATS cannot tell the Truth about something this simple, how can we ever TRUST anything that they say??? How can we ever support or vote for one of them again???

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