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Polar Melting May Raise Sea Levels Faster than Anticipated

The height of the Greenland ice sheet at present (left) and during the last interglacial (about 130,000 years ago), as simulated by the NCAR-based Community Climate System Model coupled with an ice-sheet model. Source: Bette Otto-Bliesner, NCAR

A set of papers published in the 24 March issue of Science suggests that the ice sheets covering both the Arctic and Antarctic could melt more quickly than expected this century.

Two studies led by scientists at the National Center for Atmospheric Research (NCAR) and the University of Arizona blend computer modeling with paleoclimate records to show that by 2100 Arctic summers may be as warm as they were nearly 130,000 years ago when sea levels rose to 20 feet (6 meters) higher than they are today.

Bette Otto-Bliesner (NCAR) and Jonathan Overpeck (University of Arizona) based their findings on data from ancient coral reefs, ice cores, and other natural climate records, as well as output from the NCAR-based Community Climate System Model (CCSM), a powerful tool for simulating past, present, and future climates.

The National Science Foundation (NSF), which provides primary support to NCAR, funded the research. The study also involved researchers from the universities of Calgary and Colorado, the US Geological Survey, and Pennsylvania State University.

The historical data describe a period in Earth’s history characterized by a high level of Arctic warming. Based on those data, the modeling experiments Otto-Bliesner and Overpeck conducted provide important insights about possible future environmental changes in a warmer world that have the potential to significantly alter our natural and man-made environments.

Although the focus of our work is polar, the implications are global. These ice sheets have melted before and sea levels rose. The warmth needed isn’t that much more than present conditions.


The two studies show greenhouse-gas increases over the next century could warm the Arctic by 5-8 degrees Fahrenheit (3-5 degrees Celsius) in summertime-—about as warm as it was 130,000 years ago, between the most recent ice age and the one before it.

The difference 130,000 years ago is that there was an increase in solar radiation over the Arctic, caused by slight changes in the Earth-Sun orbit, which is a normal cycle that occur over tens of thousands of years. This time around the warming is man-made, caused by carbon dioxide emissions, but the effects on Arctic sea ice, permafrost, and icefields are forecast to be similar.

—Dr. Shawn Marshall, University of Calgary

Although simulation results depend on the assumptions and conditions of different models, estimates of warming from the CCSM are within the range projected by other climate models, according to the authors.

Getting the past climate change correct in these models gives us more confidence in their ability to predict future climate change.


The CCSM suggests that during the interglacial period, melt water from Greenland and other Arctic sources raised sea level by as much as 11 feet (3.5 meters), says Otto-Bliesner. However, coral records indicate the sea level actually rose 13-20 feet (4-6 meters) or more. Overpeck concludes that Antarctic melting must have produced the remainder of the sea-level rise.

These studies are the first to link Arctic and Antarctic melting in the last interglacial period. Marine diatoms and beryllium isotopes found beneath the West Antarctic Ice Sheet indicate parts of the ice disappeared at some point over the past several hundred thousand years.

Overpeck theorizes that the rise in sea levels produced by Arctic warming and melting could have helped destabilize ice shelves at the edge of the Antarctic ice sheet and led to their collapse. If such a process occurred today, it would be accelerated by global-scale greenhouse-induced warming year round, Overpeck says. In the Arctic, melting would likely be hastened by pollution that darkens snow and enables it to absorb more sunlight.

A study by Robert Bindschadler, a glaciologist at NASA’s Goddard Space Flight Center confirms that warmer water temperatures are creeping into the Earth’s colder areas, increasing melting and accelerating ice flow in polar areas.

Temperatures collected from ships and buoys showed a warming of all oceans. That increase began before satellite sensors detected temperature increases of sea surfaces. Most of the warming was limited to the oceans’ upper 1,000 meters (.62 mile), except in the North Atlantic. In the cold North Atlantic waters, heat penetrated even deeper. This warming has increased the melting of sea ice in the North Atlantic.

These warm waters are beginning to melt the underside of the floating fringes of the Greenland ice sheet, even at great depths, It is these fringes that have been holding back vast stores of ice locked up in the Greenland ice sheet, and as this ice has been melting, the glaciers have hastened their flow to the sea.

A recent assessment in the changes in speed and the amount of snow and ice around Greenland confirms a large melting of outflow glaciers and acceleration of ice flow. Three large glaciers, the Kangerdlugssuaq, Helheim and Jakobshavns Isbrae have been melting at a rapid rate over the past several years.

Jakobshavns, the largest outlet glacier on Greenland’s east coast, has been annually thinning at 15 meters (49.2 feet) since 1997. The other two glaciers have also been thinning. Kangerdlugssuaq at 40 meters (131.2 feet) per year and Helheim at 25 meters per year (82.0 feet), which can’t be explained by normal melting. All of these glaciers have also been accelerating. Scientists are seeing similar behavior in Antarctica as well.

In another paper, a team from Harvard University and Columbia University report an unexpected offshoot of global warming: “glacial earthquakes” in which Manhattan-sized glaciers lurch unexpectedly, yielding temblors up to magnitude 5.1 on the moment-magnitude scale, which is similar to the Richter scale.

Glacial earthquakes in Greenland, the researchers found, are most common in July and August, and have more than doubled in number since 2002.

People often think of glaciers as inert and slow-moving, but in fact they can also move rather quickly. Some of Greenland’s glaciers, as large as Manhattan and as tall as the Empire State Building, can move 10 meters in less than a minute, a jolt that is sufficient to generate moderate seismic waves.

—Göran Ekström, Harvard

As glaciers and the snow atop them gradually melt, water seeps downward. When enough water accumulates at a glacier’s base, it can serve as a lubricant, causing blocks of ice some 10 cubic kilometers in size to lurch down valleys known as outlet glaciers, which funnel all of Greenland’s glacial runoff toward the surrounding sea.

Our results suggest that these major outlet glaciers can respond to changes in climate conditions much more quickly than we had thought. Greenland’s glaciers deliver large quantities of fresh water to the oceans, so the implications for climate change are serious. We believe that further warming of the climate is likely to accelerate the behavior we’ve documented.

—Meredith Nettles, Columbia

Seismometers worldwide detected 182 earthquakes in Greenland between January 1993 and October 2005. The research team examined the 136 best-documented of these seismic events, ranging in magnitude from 4.6 to 5.1. All 136 temblors were found to have originated at major valleys draining the Greenland Ice Sheet, implicating glacial activity in the seismic disturbances.

Of the 136 earthquakes analyzed, more than a third occurred during the months of July (22 earthquakes) and August (24 earthquakes). By comparison, January and February each saw a total of only four earthquakes between 1993 and 2005. Non-glacial earthquakes in polar regions show no seasonal variability.

Greenland’s overall number of glacial earthquakes also increased markedly between 1993 and 2005. Annual totals hovered between 6 and 15 through 2002, followed by sharp increases to 20 earthquakes in 2003, 24 in 2004, and 32 in the first 10 months of 2005. A single area of northwestern Greenland, where only one seismic episode was observed between 1993 and 1999, experienced more than two dozen glacial quakes between 2000 and 2005. Polar regions have not experienced increases in non-glacial earthquakes in recent years.

While the glacial earthquakes appear most common in Greenland, the scientists have also found evidence of glacial earthquakes originating at mountain glaciers in Alaska and at glaciers located in ice streams among the edges of Antarctica.




I found this newly-published paper on solar forcings interesting.


We estimate that the sun contributed as much as 45–50% of the 1900–2000 global warming, and 25–35% of the 1980–2000 global warming. These results, while confirming that anthropogenic-added climate forcing might have progressively played a dominant role in climate change during the last century, also suggest that the solar impact on climate change during the same period is significantly stronger than what some theoretical models have predicted.

Rafael Seidl

Cervus -

you make a good point. The current debate is focussed mostly on if/how we can reduce anthropogenic CO2, with the implied assumption that doing so would avert the risk of climate change. This may well be naive, both because we may already have crossed the Rubicon and, because unrelated solar activity may be reducing what margin of safety remains.

The issue then is no longer just if/how we can avoid climate change but if we can/need to buy time by at least not accelerating the process. In this context, we need to start asking some unpalatable damage limitation questions:

What would we do if sea levels rose, the Gulf stream collapsed, hurricane activity increased or some other specific climate change phenomenon became real enough to have a significant lasting impact our societies and economies?

How would we soften the impact on those hardest hit in a nonviolent, socially responsible manner, both nationally and internationally?

Which specific metrics would trigger these contingency plans?


My view is that adaptation, rather than prevention, is key. Although human activities do affect our climate and atmosphere, there are a lot of other forces at work that we cannot control. The climate will never, ever remain static. The one constant in this world is change. Otherwise there'd be no Ice Ages, no Holocene Maximums.

We are arguably making the situation worse, but if the above paper is verified, our role in climate change is less than we thought it was. But it is increasing.

The only way we're going to mitigate this is by being wealty enough to afford investments into alternative sources (like oil from algae, my personal favorite process), and invest in them.

I also found this article about the climate and the Carboniferous Period. The author argues that continental configuratios play a large role in the formation of polar ice caps and Ice Ages.


I have seen it suggested that at this point, with the uncertainty facing us, the most cost-effective short-term measure is to STOP or at least reduce additional development in coastal areas, particularly highly vulnerable ones like the U.S. gulf coast. Every new hotel, resort and housing development built in these vulnerable areas is money spent that will add to the costs if and when those lands are directly threatened.

Luckily this is something that can generally be handled by the free market, i.e. individual incentives. Insurers are becoming gun-shy about additional investment in these areas as the weather becomes more chaotic. As insurance becomes more expensive, developers will begin to look elsewhere for their projects.

Most other measures that have been proposed, like Kyoto, are simultaneously extremely expensive and basically too small to make any difference. At this point there is nothing we can do to stop CO2 levels from continuing to rise well into the 400+ ppm region that has been called a point of no return. It is highly unlikely that we can stop at less than 500 without a worldwide depression.

That means that all these consequences, warming, rising sea levels, are basically going to happen no matter what we do. At this point our best strategy is to try to stop making things worse if and when they do happen, and as I noted the cheapest way to do that is to stop building new vulnerable infrastructure. That is the most cost-effective action available today.


I doubt society will change its ways so....

Personally, I think our only recourse is to reduce the insolation that the earth recieves. NASA recently proposed placing a semi-reflective surface of about 1 squre kilometer in a near sun orbit. The goal would be to reduce the insolation recieved from the sun by 1 to 2 percent. This could drastically cool our planet and at least provide short term relief from our seemingly out of control spiral.

Hard to imagine... I know. So were nuclear warheads/reactors not too long ago.

I'll dig up a link to NASA's proposition...


"and 25–35% of the 1980–2000 global warming"

... funny how many people out there will take that as a "majority" driver.

Rafael Seidl

Cornelius -

how would we go about putting something that huge into earth orbit, let alone get it into "near sun orbit" and keep it there? Solar mass ejections would reduce it to shreds before long. This is quite unlike the (also weird) recent Russian project to use a much smaller solar sail in Earth orbit to see if sunlight could be reflected toward Siberia.

The one thing you are right about is that it is possible to achieve global dimming. We're doing it today, albeit only a little and that inadvertently, by pumping aerosols into the atmosphere. Ironically, cleaning up diesel cars with particulate filters will remove a major source of these aerosols.


I believe the observed global cooling that happened between 1940-1970 (Resulting in Ice Age fears) was probably the result of these areosols. I guess we can't win.

Another article I found about the reliability of ice core CO2 data. The author argues that the 280ppm preindustrial estimate is invalid due to chemical changes in the air bubbles, since ice cores are not a closed system. The median of directly-measured levels in the 19th century was 335ppm.

Joseph Willemssen

I'm continually amused by the "it's a coincidence" contingent.

tom deplume

How do they know what the solar flux was 100-200 years ago?
CO2 measurements at Monua Loa have been recorded long enough to show a direct relationship between fossil fuel use and CO2 levels and average temps.


We should close all coal, gas and oil plants and replace them with renewables and nuclear power.

Or we should at least ban new contruction of coal, oil and gas plants. The current fossil plants will be retired in a few of decades and then only renewables and nuclear power will remain.



Do you realize that you "solution" is a very expensive one which may actually do more harm than good? Up to date cola fired plants remian the cheapest and most reliable source of power. Nuclear is very expensive and even though it doesn't directly emmit CO2, its production and fuel enrichment does consume fossil fuels which produce CO2 and it also has waste disposal issues. All these other renewables are either too expensive or highly unrealiable.

Rafael Seidl

Starvid -

I hope we'll eventually figure out ways to make do with renewables and geothermal heat alone. There might be a breakthrough in nuclear fusion, but it would be folly to count on it.

The problem with nuclear fission is not so much uranium supplies or even the accident safety of modern designs such as pebble-bed ractors - as opposed to the many legacy reactors. It is dealing with the risk of weapons proliferation, the risk of terrorist attack and above all, the long-term storage of spent fuel and decomissioned reactor components.

The US has spent many years on its Yucca Mountain project, but the local NIMBYs are (understandably) opposed to making Nevada the nation's radioactive waste dump.

In Germany, a person recently died in an accident while protesting rail transports to the Gorleben salt mine. There is now concern that natural gas exploitation in the area could be causing earthquakes, typically <2 on the Richter scale but with the potential for more. The impact that might have on the long-term viability of the nuclear storage facilty is uncertain.

The French operate a reprocessing plant (they used to operate fast breeders as well). Both technologies involve handling industrial quantitites of the most dangerous substance known to man, plutonium. There was an uproar some years ago when the Japanese sent their spent fuel half-way around the world for reprocessing. What if the ship sinks or pirates steal it?

A final mechanism for reducing the volume of radioactive waste is using a particle accelerator to fire protons at it in a sub-critical reactor, yielding yet more useful energy. The final waste stream has a half-life of "just" several centuries, but the radiation intensity is of course much higher than for the primary waste. That means it is still hazardous for many thousands of years.

Austria built a reactor at Zwentendorf in the 70s but public protests prevented it from ever being switched on; the country has never really looked back. If Iran wanted to back out of its nuclear ambitions without losing face, it could cite Austria as an example.


Cervus. Suggest you read the following analysis of the impact of the sun on climate change.


Cervus: Here is the skinny on your referenced World Climate Report. Perhaps you should have made this clear before you posted. Not surprised that this group would try to claim a big role for solar flux.

A newsletter on global warming, ozone, "sound science". WCR is sponsored by the Greening Earth Society, a Western Fuels Association project founded to spread the "good news" that global warming is benficial for the planet.

Look at the resumes of those who write for the site This are real and accomplished climate scientists with decades of experience and knowledge. I think you would be better off getting you climate knowledge from these people rather than a web site that is a tool of the fuel industry. Even if your data is accurate, it hardly suggests that we should be less concerned with the impact of greenhouse gas emissions.


You bring up interesting issues.


Nuclear power is cheaper than gas in most places due to the high cost of gas. Nuclear power is cheaper than coal except where there are high grade coal deposits close to the power plants, mainly in the USA and Australia. But the external costs for coal are immense. Not only global warming but also respiratory disease. According to the EU Externe study nuclear is the cheapest way to make power when all external effects are included. And remember France (80 % nuclear) has among the cheapest power in Europe.

Rafael Seidl:

I agree proliferation is the single biggest problem for nuclear power, way bigger than cost or handling of waste. But I believe it can be managed. Not all countries require all parts of the nuclear fuel cycle. The sensitive parts like enrichment and reprocessing could be reserved for the Great powers.

Waste management shouldn't be a problem. I live in Sweden and the counties where the nuclear plants are situated are fighting each other to get the high level waste repository because of all the jobs it'll bring. I happen to live in the county where the repositry will most likely be located (70 km from my home) and I don't complain. Nor do any one I know.

Plutonium is not that dangerous at all. You can handle solid plutonium as long as you have a gas mask and gloves. Plutonium is an alfa emitter and is only dangerous if you breathe plutonium dust. Plutonium can be handled, and has been handled in a safe way for decades.

Shipping is not a problem either. The nuclear fuels ships are escorted by warships. Even if pirates captured one, what should they do with 100 ton heavy transport canisters? If they manage to open them (with anti-tank explosives) they'll get a fatal radiation dose. Don't worry about that issue.

Gentlemen, we face an enormous issue. In the end it boils down to nuclear or coal. Nuclear has issues, but climate change is 1000 times worse. We have to choose the least bad realistic alternative.

Understanding this will be a major challenge for the environmental movement.

And then it will be a huge challenge to implement it.

James White

I strongly disagree with the positions being put forth by Rafael Seidl, Cervus, Alan, Hal, and company. They sound like the rest of the paid liars from Exxon. In their view nothing can be done to stop global warming, so get used to it and just learn to live with the consequences. They used to argue that global warming wasn't happening, but "that dog don't hunt no more". Now they are saying it is natural, not caused by fossil fuels, but if it is, it's too late to do anything about it.
If they are not going to offer Green Car solutions to address climate change, then I hope they find another forum to spread their misinformation.


Nuclear power and gas generated electricity do not compete with each other. Nuclear has very high fixed costs to with its fuel costs are neglectable. Gas has very high fuel costs but the fixed costs are cheap so it is cheapest to produce electricity with gas during peak demand.

Rafael Seidl

James White -

I think your rant is fairly wide of the mark. I absolutely advocate sensible green technologies (automotive and otherwise), mostly to contribute in a small way to avoiding future armed conflicts over various natural resources.

In particular, I did not state that climate change cannot be avoided. I don't know if that's possible. Solar activity may or may not be an exacerbating factor so we have to assume to assume it might be - which makes action on our part more urgent, not less!

It's just that human nature being what it is, chances are the industrialized nations will end up taking too little action too late. Perhaps the exercise of drawing up concrete contingency plans would get the stragglers to wake up to the risks we are taking.

Starvid -

sadly, your assertion that "the sensitive parts like enrichment and reprocessing could be reserved for the great powers" flies in the face of reality. India, Pakistan, North Korea and Israel all developed nuclear weapons technology under the cloak of civilian programs. Iran stands accused of doing the same right now.



your remark that Austria hasn't looked back after rejecting nuclear is not supported by other commentators

More pointedly it seems every developed country is seriously thinking of nuclear.


Rafael Seidl:

As far as I am concerned India is a Great power and can have both nuclear power and nuclear weapons.

Israel is also a Great power at least militarily. But Israel, Pakistan and Noth Korea have all paid for their insolence by being shut out of all international fuel cycle activities. North Korea has been declared a pariah state.

The only reason the same thing hasn't been done with Israel and Pakistan is that they are regional Great powers.

Rafael Seidl

Aussie -

none of the political parties here advocates revisiting nuclear power generation in Austria - it's the proverbial third rail. At the recent EU summit, leaders agreed to disagree on the subject because other nations don't have the luxury of hydroelectric dams. Moreover, some feel overly dependent on oil & gas from their former colonial masters in the Kreml.

Starvid -

my intent was to underline that non-proliferation safeguards - such as they are - are simply no longer effective.

North Korea used to be a signatory to the NPT but simply canceled its membership when it became inconvenient. China and South Korea continue to appease the "Dear Leader" in spite the threat he represents because they don't want 20+ million refugees on their doorstep.

Iran remains a signatory to the NPT but recently opted out of the additional protocol. They just announced a successful experiment linking hundreds of UF6 ultracentrifuges in a cascade, which can be used for producing fuel rods (5% enrichment) or, at a larger scale, for producing weapons-grade uranium. Do you believe their pious claims?


The U.S. only supports nonproliferation when it comes from their perceived enemy. We still have an obligation to reduce and elminate nuclear weapons. We blink at Israel, India, and Pakistan. The piper will be paid eventually. On the bright side, maybe we can get some termporary cooling when the big bombs go off.

allen zheng

what happened to aerosoling white/silver particles in the upper atmosphere made of calcium carbonate (limestone) or other natural rock based light reflecting particle? Especially over Antartica above the Antartic circle?


that's being done globally by mostly military aircraft as an unacknowledged special access project, although with things like barium salts... watch the sky fill up with the crud!

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