Die lebenswichtige Rolle des Eises im arktischen Meer: Interview mit Dr. Ted Scambos & Dr. Mark Serreze
On February 28, the breakup of Antarctica's Wilkins ice shelf into the ocean, which measured 406 square kilometers, made headlines around the world.
This alarming discovering was made by Dr. Ted Scambos from satellite images. Dr. Scambos is the senior research scientist at the National Snow and Ice Data Center (NSIDC) at the University of Colorado in the United States.
Dr. Mark Serreze is also a senior research scientist at NSIDC and a Cooperative Institute for Research in Environmental Sciences (CIRES) fellow. He is a member of the American Geophysical Union and the American Meteorological Society.
Dr. Serreze has published numerous reports on his findings of the Arctic's shrinking sea ice cover. Currently, he is evaluating the causes for the decline in Arctic sea ice.
On today's Planet Earth: Our Loving Home, Drs. Scambos and Serreze, share their expertise in an interview with Supreme Master Television.
Let's now hear from Dr. Serreze on his research in the area of glaciology, polar science and what the implications of their discoveries of Arctic sea ice melt mean in terms of climate change.
Supreme Master TV: My first question is why the Arctic Sea ice is so important to keep the ecological balance of the earth?
Dr. Serreze: we think of the Arctic, we can think of it as the refrigerator of the Northern Hemisphere climate system. Now, of course, part of that refrigerator is just located far to the North so that the sun's rays don't strike as directly as they would in the Equatorial regions. But another big part of this is the existence of that sea ice cover itself.
It is reflective so most of the sun's energy that hits that surface is bounced right back up into space again, and keeps the Arctic cool. But now we are warming the system up, and what we are starting to do is lose that sea ice, that reflective sea ice.
We are changing the nature of that Arctic refrigerator. The thing is, is that everything in the climate system is coupled together. Eventually what happens in the Arctic influences what happens down here; I am talking say at middle latitudes like of the Unites States.
Supreme Master TV: When you think of losing ice in the Arctic, what's the biggest impact?
Dr. Serreze: When we think of losing Arctic ice, we can think of two components of the ice. One of them would be that ice which is locked up in the ice sheet, and we are talking here about Greenland.
Now when we start to melt down Greenland, that has an impact on the sea level and there's strong evidence that that is in fact happening right now.The other component of what we call the aqueous sphere in the Arctic, is the sea ice.
Supreme Master TV: I see.
Dr. Serreze: Now the melting of the sea ice, loss of the sea ice itself does not have an effect on the sea level. Because that ice was already floating, it's very different than Greenland. However, what we are talking about is loss of a very large area of a very white surface, this white surface.
Albedo is the reflectivity of a surface. Snow and ice if you could see it has high albedo, [and when] we lose that sea ice cover, we reduce that Albedo, we make that surface darker, [so it] absorbs more of the sun's energy, the Arctic heats up.
But everything is connected, so if we change the Arctic sea ice cover, we change these patterns of heating, the atmospheric circulation responds to changes in heating.
So the argument is, you lose that sea ice cover you start to impact things like patterns of weather, patterns of participation outside of the Arctic.
We think of the Arctic sometimes as this faraway place, what happens there doesn't matter, but we are starting to learn is that it indeed does matter.
Supreme Master TV: This is why they talk about feedback and that type of thing where it just goes in a circle, like a downward spiral.
Dr. Serreze: Exactly, this is the whole concept of feedback. Even our earliest climate models of circulations have been telling us that as we start to increase greenhouse gas concentrations it's in the Arctic where we are going to see the changes first and it's in the Arctic
where those changes are going to be doubly pronounced, and a large part of that sensitivity is due to these feedback processes.
The idea is that once you hit the system with something, the effect of it starts to snowball, and the most important feedback in the Arctic is associated with this change in albedo, especially associated with this ice cover.
We warm up the climate a little bit by putting atmospheric greenhouse gases in it, we melt some of this highly reflective snow and ice cover, that means more of the sun's energy is absorbed, the Arctic becomes warmer as a result, that means more of the snow and ice cover melts, the Arctic becomes even warmer so it's a feedback that we call it, a process that feeds on itself.
HOST: Dr. Ted Scambos specializes in studying the glaciers of Antarctica. He was first to discover the collapse of the Wilkins ice shelf in Antarctica via satellite images and lead a team of international scientists to study the region.
Dr. Scambos was a contributor of the report, Climate Change 2007: The Physical Science Basis for the UN's Nobel Peace Prize winning Intergovernmental Panel on Climate Change (IPCC).
He shares his knowledge on the significant role of ice in the polar regions here on Supreme Master elevision
Dr. Scambos: The only other component that's slightly different is the ozone hole in Antarctica, which is also caused by human activity, but the main event in 2002, I think, really was a turning point. It's an iconic image for saying that the Earth is changing because of warming; the blue patch of ice crumbling away, streaming across the ocean.
That's become an iconic image; it's been used hundreds of times by newspapers,books, magazine articles.
Supreme Master TV: There have been broke up of ice shelves that are much larger than that, still, in the past, in 1955 or something, I thought.
Dr. Scambos: In 1955, there was an iceberg that was sighted that was supposedly larger than the largest iceberg that's been mapped today.
I've looked at that newspaper story and I've looked at some of the ice shelves. That's normal, and Antarctica's been behaving that way for millions of years.
What's not normal is to see melt ponds on the surface, no sea ice in front of the ice shelf edge, and a sudden break-up, not just in one big piece, but crumbling down, disintegrating, absolutely blowing itself up within just a few weeks. The other thing is that the ice shelf doesn't recover from it.
There's no re-growth; there's no new shelf that starts to push out in the aftermath of one of these events.
HOST: The dramatic changes in the Arctic sea ice melts is a definite sign of the acceleration of global warming. Dr. Ted Scambos will further explain on other changes found in ice shelves of the polar regions when Planet Earth: Our Loving Home returns.Please stay tuned to Supreme Master Television.
Dr. Ted Scambos, senior research scientist at the University of Colorado's National Snow and Ice Data Center and the lead scientist who discovered the recent collapse of the Wilkins ice shelf speaks with Supreme Master Television.
Supreme Master TV: Do you see any immediate threat to the ice shelf now that you look at it? Larsen A ice shelf fell off, right? And Larsen B already fell off recently, right? Are we watching C?
Dr. Scambos: Yes, there is a C, and there are plans to visit it as part of the International Polar Year. There're two major efforts, one from Great Britain and a joint effort between Chile and the U.S. to visit Larsen C and set up measurements so that we know what it was like before it really began to retreat due to global warming. We thought that the only way that you would lose an ice shelf is part of global warming, but the only way you lose it is through this very slow process of calving and surface melting.
You have to wait for the warmth to reach the point where from the bottom of melting by the ocean and from the top of melting by the air, that both of those things to conspire to thin the ice shelf to zero.
But we didn't anticipate that there was this runaway process of fracturing that happens once you get the top soaked with water, the water actually acts to blow the ice shelf apart. Not by frost heat , this is something people in the north are familiar with, rocks can be split open by a film of water that gets into the crack.
It's not quite the same process. (Okay.)
If you get a tall column of water there's quite a bit of pressure at the bottom. And since ice is less dense than water or ice floats on water, the ice doesn't have the same level of pressure;
it's not as dense. So, at a bottom of a crevasse, it begins to fill with water because there's no water on the surface. At the bottom of that crevasse, you get to a point where the pressure is so high that just the weight of the heavy water inside the lighter ice is enough to crack through the ice and drive it all the way to the bottom. It was something that had been talked about for some glaciers but had never been - nobody had ever thought that it could happen on such a large scale so suddenly on an ice shelf. Right now, that's still the best model. There were some other things;
people have talked about how the oceans are getting warmer, thinning the ice from underneath, how the ice shelf, because it was thinning, was starting to lose contact with coastline, starting to break away from the coast.
But in terms of what happened in March of 2002 and earlier in 1995 for the Larsen A, that had to do with water fracture in the ice very suddenly one hot summer. So, if we got one really hot summer between now and 2020, we could see the Larsen C do the very same thing.
Dr. Scambos: What we've seen is that ice shelves are good indicators of climate change because they respond not only to air temperature on the surface, where the rest of the ice sheet responds too, but also to warming in the ocean underneath. That starts to trim them underneath, so they respond very quickly. The bad news is that these ice shelves are all fed by these glaciers coming off of the large ice sheet.
When you break the ice shelf away, take that away, all of those glaciers accelerate very rapidly, flowing into the ocean, calving very rapidly and dumping ice that was on the continent out on the ocean.
This is another case where glaciologists were surprised beyond their wildest imagination as to how fast the system could respond. We went from four glaciers that fed the Larsen B that were flowing at about a rate of one meter per day, to feeding it at six to eight meters per day, within the space of one year, a year and a half, after the loss of the Larsen B ice shelf.
If that happens elsewhere in Antarctica where there are even larger glaciers, we'll see very sudden jumps in the rate of sea level rise.
Dr. Scambos: It's clear that ocean warming along the southern Greenland coast and also on the western side of Greenland, the part that's close to Canada, glaciers are responding very rapidly; they respond in particular to surface melting and to warmer oceans.
The trigger that appears in Greenland appears to be a warmer ocean, and then melting on the surface appears to accelerate the flow into the ocean, from things that were triggered by a warmer ocean.
In Antarctica right now, in the peninsula, it seems as though air temperature is leading the way,
but elsewhere in Antarctica, ocean temperature's creeping up at depth, because the surface water in Antarctica and the surface ice in Antarctica is still quite cold. But underneath that cold layer, warm water from elsewhere in the world, from the temperate parts of the world is seeping in, and if there's a very deep layer of ice that's
touching the ocean, it's being melted away and breaking up and accelerating, even though Antarctica is remaining quite cool so far.
So, in the poles, anybody who works in polar science, nobody questions whether or not we're in trouble, a warming world, because we see it in our field areas every year.