- Michael Van Woert, NOAA NESDIS, ORA. National Oceanic and Atmospheric Administration/Department of Commerce
- This view of the seaward edge of Antarctica’s floating Ross Ice Shelf shows a region where the ice is cracking and may produce an iceberg.
UA scientists are part of a team that suggests that the Greenland and Antarctic ice sheets are going to melt faster than anticipated because of warming oceans. Mari Jensen of UA News brings us details from a paper that’s being published today in Nature Geoscience:
Warming of the ocean’s subsurface layers will melt underwater portions of the Greenland and Antarctic ice sheets faster than previously thought, according to new University of Arizona-led research. Such melting would increase the sea level more than already projected.
The research, based on 19 state-of-the-art climate models, proposes a new mechanism by which global warming will accelerate the melting of the great ice sheets during this century and the next.
The subsurface ocean layers surrounding the polar ice sheets will warm substantially as global warming progresses, the scientists found. In addition to being exposed to warming air, underwater portions of the polar ice sheets and glaciers will be bathed in warming seawater.
The subsurface ocean along the Greenland coast could increase as much as 3.6 F (2 C) by 2100.
“To my knowledge, this study is the first to quantify and compare future ocean warming around the Greenland and the Antarctic ice sheets using an ensemble of models,” said lead author Jianjun Yin, a UA assistant professor of geosciences.
Most previous research has focused on how increases in atmospheric temperatures would affect the ice sheets, he said.
“Ocean warming is very important compared to atmospheric warming because water has a much larger heat capacity than air,” Yin said. “If you put an ice cube in a warm room, it will melt in several hours. But if you put an ice cube in a cup of warm water, it will disappear in just minutes.”
Given a mid-level increase in greenhouse gases, the researchers found the ocean layer about 650 to 1,650 feet (200 to 500 meters) below the surface would warm, on average, about 1.8 F (1 C) by 2100.
Along the Greenland coast, that layer would warm twice as much, but along Antarctica would warm less, only 0.9 F (0.5 C).“No one has noticed this discrepancy before — that the subsurface oceans surrounding Greenland and Antarctica warm very differently,” Yin said.
Part of the warming in the North comes from the Gulf Stream carrying warm subtropical waters north. By contrast, the Antarctic Circumpolar Current blocks some of the subtropical warmth from entering the Antarctic’s coastal waters.
Even so, the Antarctic ice sheet will be bathed in warming waters, the team writes.
Co-author Jonathan T. Overpeck said, “This does mean that both Greenland and Antarctica are probably going melt faster than the scientific community previously thought.”
Overpeck, a UA professor of geosciences and co-director of UA’s Institute of the Environment, said, “This paper adds to the evidence that we could have sea level rise by the end of this century of around 1 meter and a good deal more in succeeding centuries.”
The paper by Yin, Overpeck and their colleagues, “Different Magnitudes of Projected Subsurface Ocean Warming Around Greenland and Antarctica,” is scheduled for online publication in Nature Geoscience on July 3.
Their co-authors are UA assistant professor of geosciences Joellen L. Russell; Stephen M. Griffies and Ronald J. Stouffer of the National Oceanographic Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory in Princeton, N.J.; and Aixue Hu of the National Center for Atmospheric Research in Boulder, Colo.
Other researchers have recently measured surprisingly high subsurface ocean temperatures along coastal glaciers in Greenland, Yin said. In addition, scientists have reported the Greenland and Antarctica glaciers that empty into the sea are moving faster.
Yin decided to figure out how much those subsurface currents would warm during this century and the next.
Glaciers are rivers of ice. Like rivers of liquid water, glaciers move downhill. Some glaciers melt before reaching the ocean, and others, called tidewater glaciers, flow all the way to the sea.
The face of a tidewater glacier visible from a boat is only part of it — much of the glacier’s leading edge is underwater in a deep fjord.
Yin’s research suggests Greenland’s glaciers are being exposed to increasingly warm subsurface water that will melt the underwater portion of the glaciers. As a result, the tops of the glaciers will no longer have support and will topple into the sea, creating icebergs. In addition, as the undersides of the glaciers melt, that meltwater will speed the glaciers’ movement into the sea by lubricating their undersides.
Ultimately, those glaciers will melt back so far they no longer reach the sea, the team writes.
In contrast, much more of the Antarctic ice sheet is based on land that is already below sea level. Therefore as the Antarctic ice sheet melts back, the leading edge of the ice sheet will continue to be underwater. As such warming and melting continues into the 22nd century and beyond, parts of the Antarctic ice sheet may disintegrate, the team writes.
Yin’s next step is examining climate models that can zero in even further on the regional effects of climate warming on the subsurface ocean and the ice sheets.
This article appears in Jun 30 – Jul 6, 2011.
Greenland was “Green” at one time , perhaps it will be again. Natural Earth cycles, enjoy!
And with the sunspots in remission, we will someday experience another ice age – isn’t Mother Nature wonderful? – she hardly knows that we’re here – and when one single volcano goes off, she spews millions of cubic miles of pollutants – more crap than man has contributed since the first cave-dweller lit up the interior of his dwelling. I think I’ll hold off on buying that Pius…
One good Solar Flare can end it all but our real threat is Global Warming due to man’s intervention? How Spiritual do yoou need to be to figure this one out, let alone your personal contribution to either end.
There will be winners and losers.
I’m happy to say Arizona will be a loser.
What was Phoenix yesterday? 118.
Yee-haw…
More of that and all these fat republicans are going to start dropping dead just going from Walmart to their SUVs. Those old rednecks can’t take the heat. They are wheezing like pale slugs under a hot spot light. Texas and Arizona are now ash trays. But it is what it is: Global warming really is just evolution’s way of getting rid of the dead dumb wood.
Meanwhile the Confederacy is drowning in Mississippi sludge and being roiled by maximum twisters. Is their anything funnier than seeing some trashy low-brow Denier-Birther sobbing over his trailer blown to smithereens and begging for federal help? Lord, how I laugh and laugh. And of course I wouldn’t lift “a finger” to help that poor dumb southern sop. He’s proven himself unfit for the future. He is a loser. He is good for a laugh and nothing more…
So I say bring on the heat baby! The liberal parts of the country are going to be okay. And I don’t care at all about republican children in Texas or Arizona, or their future. And it is true, the sins of the fathers’ should be visited on their children. That is environmental justice. That is evolution. Red-neck land is going to fry and flood. So be it. I’m happy. And the sooner we make the future miserable for those parts of the country the better. I am all FOR global warming, and will do what I can to make it worse…
Enjoy!
There are lots of predictions on the recent weather patterns we experience these days. They claim to tell that the sun spots are decreasing but we are experiencing hot temperatures. How come this is altered the opposite way?
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Romel @ http://reduce-stretch-marks.com/revitol-re…
Llrnccrp@aol.com, nice talking about about volcanoes, what is your source?
I say you are wrong and just spewing a Fox talking point…
“According to the U.S. Geological Survey (USGS), the world’s volcanoes, both on land and undersea, generate about 200 million tons of carbon dioxide (CO2) annually, while our automotive and industrial activities cause some 24 billion tons of CO2 emissions every year worldwide. Despite the arguments to the contrary, the facts speak for themselves: Greenhouse gas emissions from volcanoes comprise less than one percent of those generated by today’s human endeavors.”
http://environment.about.com/od/greenhouse…
http://www.livescience.com/14591-carbon-di…
http://environment.about.com/gi/o.htm?zi=1…
Is climate change primarily caused by humans? I personally do not know, I just go by what the majority of scientists have concluded. The science is the science. Thousands of researchers worldwide are working on the problem of climate change and most of them are not Americans – or democrats -let alone republicans.
However, I do see how our society and culture is unsustainable. From our dependency of oil, coal and other dirtier and hard to get resources. The fact we are running out of easy sources of oil. Drilling in the ocean, drilling on a ice sheet (Alaska), and other harder areas to drilling is not going to drive down price. Drilling in those areas cost a lot more than drilling in Texas, Saudi Arabia and on land. Plus with the increasing demand from China, India, and other developing countries are going to put even more of a demand. Also if you believe in peak oil, which makes sense since oil is a finite resource, we need to move off of fossil fuels.
Not to forget our unsustainable industrial farming (which relies heavily on fossil fuels), unsustainable mass fishing, and our unsustainable consumer driven society.
The benefits of changing our lifestyle are numerous..
-energy independence
-preserving rainforests
-sustainability
-new green jobs
-cleaner, livable cities
-clean water and less pollutants in our enivorment
But hey What if global warming is a hoax and we create a better world for nothing? We should just keep polluting, maybe our kids will figure it out in the future…after they deal with the 13 TRILLION dollars that was smacked onto our debt in only 30 years. I do not blame myself and my generation for all these problems. I blame the baby boom generation for not leaving us a better world that their parents did. How is listening to neo-conservative, supply side, free trade, de-regulation idea that Rush keeps talking about working out for you?? Don’t worry, your kids will just deal with it after you are long and gone…
Nate1980: Is climate change primarily caused by humans? I personally do not know…
Quit bending over backwards to satisfy the Fox News Bleacher Bums…
The science is so simple only a Limbaugh Dunce could be propagandized into doubting it:
CO2 in atmosphere in 1960 was 313 ppm.
CO2 in atmosphere now 383 ppm.
The Keeling curve is indisputable. It is time to man-up and admit in AGW (Anthropogenic Global Warming). Of course most Fox News sluts don’t even know the Keeling graph exists. They are “programmed” to be ignorant and spread their legs for free. But know this: GW is caused by man, and it will severely impact red states more than blue states. That’s a good thing.
http://scrippsco2.ucsd.edu/home/index.php
Now wait a minute… You Eco goons can’t have it both ways. Back in the 1970’s you were all saying that we were headed for another Ice Age. Now we are supposedly headed in the other direction. Just admit it; it’s all about wealth re-distribution and bringing down the U.S. We have stopped drilling for oil in OUR waters, but yet lease or sell the platforms to foreign countries. How is this helping to “Save the Planet”? It doesn’t. It hurts us and helps the other countries. We have to stop sacrificing our country on the alter of political correctness and climate change. You libs will have a hard time paying for all your crap when we eventually stop producing anything in this country except homeless and unemployed. And as far as the melting ice, it will cause the oceans to rise just like a glass of ice water overflows when the ice melts. Idiots!