Photo: Jefferson Beck/NASA

by Michael D. Lemonick, via Climate Central

The sea ice that blankets the Arctic Ocean each winter peaked in early March this year, as usual, and is now in retreat, en route to its annual minimum extent in September. How low it will go is something scientists worry: Ice reflects lots of sunlight back into space, and when the darker ocean underneath is exposed, more sunlight is absorbed to add to global warming.

That’s the simple version of the story, but things look even worse when you dig into the details. For one thing, all that open water does re-freeze each winter, but it freezes into a relatively thin layer known as seasonal, or first-year ice. Because it’s so thin, first-year ice tends to melt back quickly the following season, giving the ocean a chance to warm things up even more in what National Snow and Ice Data Center director Mark Serreze has called a “death spiral” that could lead to ice-free Arctic summers by 2030.

But it’s worse than that, says a new analysis by scientists at the U.S. Army’s Cold Regions Research Laboratory in Hanover, N.H. “First-year ice is not just thinner, “ said Donald Perovich, lead author of a report in Geophysical Research Letters, in an interview. “We’re also beginning to realize it has other properties.” The most important: New ice is less reflective than old ice, for most of the year, anyway. It absorbs more heat from the Sun, which means it doesn’t just melt faster: It actually speeds up its own melting.

Here’s how it happens, according to Perovich. “Most of the precipitation in the Arctic,” he said, “happens at the end of summer and in the early fall.” When the snow first begins to fall, it builds on the multi-year ice, but disappears onto the patches of open ocean. Those patches eventually freeze, and the snow sticks there as well; it just forms a thinner layer. So for most of the winter, all of the ice, thick and thin, is covered with a brightly reflective blanket. That would be good as far as warming is concerned, except that for most of the winter, the Sun doesn’t rise.

When the Sun finally does rise in spring, it melts the thinner snow first, forming heat-absorbing pools on the surface of the first-year ice. The older ice eventually catches up, forming pools of its own, but since the surface is crumpled, the ponds don’t spread as widely, and they absorb less heat.

In short, the death spiral — where more melting leads to more melting — appears to be even steeper than anyone thought.

Read more

by Michael D. Lemonick, via Climate Central

It’s just two weeks since a paper in Nature flagged an ominous thinning of ice shelves along parts of the Antarctic coast lying due south of the Pacific Ocean. The ice appears to be melting from below, as changing ocean currents are bringing relatively warm water to bathe the shelves’ undersides — and as the ice shelves lose mass, they also lose their ability to slow land-based ice in its slide toward the sea.

Now there’s something new to worry about. A pair of brand-new studies published today, one in Nature and one in its sister publication Nature Geoscience, are pointing to yet another danger zone, this one on Antarctica’s Weddell Sea coast, nestled in the armpit of the Antarctic Peninsula. The first study asserts that warm ocean currents are likely to eat significantly into the huge Filchner-Ronne Ice Shelf by 2100; the second argues that the lay of the land underneath the shelf makes the ice even more unstable than it would otherwise be. “We don’t necessarily have any evidence for a dramatic change right now,” said Martin Seagirt of the University of Edinburgh, a co-author on the second paper, in a press conference, “but it’s on the threshold.”

The reason, say Seagirt and his colleagues, is that airborne radar shows that the ice shelf sits atop a depressed basin of bedrock about 60 miles wide by 160 miles long by up to a mile and half below sea level at its deepest. Right now, the so-called grounding line — the place where a shelf makes the transition from grinding along the rock to floating freely in the sea — lies at the outer rim of that basin. As warmer water melts the ice back, it can flow into the basin and cause the ice within to detach from the bedrock relatively quickly. “Its very nearly afloat already,” Seagirt said. “It needs some push and we don’t believe the push needs to be very hard.”

It’s exactly that sort of push that emerges from the work of Hartmut Hellmer, of Germany’s Alfred Wegener Institute for Polar and Marine Research and his colleagues. The scientists used a state-of-the-art climate model known as HadCM3, which simulates the responses of both atmosphere and oceans in a warming world, to test what might happen to the frigid waters off Antarctica as temperatures rise.  They found that a 7°F warming of the atmosphere — on the high end of what scientists expect by 2100, but still well within the plausible range — could warm the Weddell Sea by 3.5°F. Since the floating sea ice in the Weddell has already begun to disintegrate, that water would have easy access to the ice sheet.

If the Filchner-Ronne lifts off the bedrock, land-based glaciers that feed it will be able to move more quickly to the sea, especially, Seagirt said, because the inland part of the basin, where it slopes back upward toward the center of Antarctica, has a very smooth floor, which is easy for ice to slide along. This suggests it used to sit at the bottom of an ocean where sediment would have plastered over outcroppings of rock— a glimpse, perhaps, of things to come.

Since the Filchner-Ronne is mostly fed by ice from the West Antarctic Ice Sheet, it’s natural to think that the much larger East Antarctic Ice Sheet, which holds enough ice to raise sea level by 160 feet or more, is safe (although with 20 feet of sea level rise potential itself the West Antarctic sheet isn’t anything to sneeze at). But the safety is by no means guaranteed: the two sheets, which are separated by the Transantarctic Mountains, aren’t completely isolated from each other. If you lose the Filchner-Ronne, Seagirt said, “there will be knock-on effects. There will be consequences for East Antarctica.”

None of this means the world is necessarily headed for apocalyptic sea level rise by the end of this century. Current projections still put the most likely increase by 2100 at about 3 feet, which is bad enough. But scientists still barely understand the dynamics of the world’s great ice sheets. They could turn out to be more stable than glaciologists expect.

Or, as these new results seem to imply, they could be much less.

– Michael Lemonick covered science and the environment for TIME magazine for nearly 21 years, where he wrote more than 50 cover stories. This piece was originally published at Climate Central and was reprinted with permission.

Related Climate Progress Posts:

• JPL: Polar ice sheet mass loss is speeding up, on pace for 1 foot sea level rise by 2050
• Nature: Antarctica Is Melting From Below, Which ‘May Already Have Triggered A Period of Unstable Glacier Retreat’
• Large Antarctic glacier thinning 4 times faster than it was 10 years ago: “Nothing in the natural world is lost at an accelerating exponential rate like this glacier.”
• Greenland Ice Sheet “Could Undergo a Self-Amplifying Cycle of Melting and Warming … Difficult to Halt,” Scientists Find

Has the melt season started in the Barents and Kara Seas two months earlier than normal?

by Neven Acropolis

We are entering the final stage of the freezing season in the Arctic. Winter time is usually a boring time for watching the sea ice. Due to the polar night there are no direct satellite images, and it’s hard to tell what’s exactly going on up there because the ice is simply everywhere, filling up the entire Arctic ocean.

This winter was looking more or less like previous years, until about a month ago. A flip in atmospheric patterns that brought very late winter conditions to Europe, also had an effect on the fringes of the ice pack on the Atlantic side of the Arctic. Large swathes of sea water in the Barents and Kara Seas that ought to have been completely frozen over, opened up and total Arctic ice growth came to a practical standstill on various graphs, such as the Cryosphere Today sea ice area graph.

The regional effect can clearly be seen on this comparison of sea ice concentration maps for February 11th in the 2004-2012 period:

Image courtesy of the University of Bremen

Novaya Zemlya, the large Russian island that divides the Barents and Kara seas, is completely ice-free. The same almost goes for Svalbard, the archipelago in the top left. I think it’s safe to safe that this is unprecedented ever since satellites started monitoring Arctic sea ice in 1979. I have been looking at the Arctic sea ice from up close for about two years now, but this is definitely one of the most spectacular things I have seen so far. It’s almost as if the melting season has already started in the Barents and Kara Seas, more than two months earlier than normal.

What could be causing such an early retreat of sea ice cover?

Read more

Zee Evans, National Science Foundation

by Al Gore, reposted from the Climate Reality Project

After crossing the legendary Drake Passage, we came in sight of the Antarctic continent. It is a majestic, otherworldly place. The Antarctic Peninsula, which juts northward toward South America, is lined with ice-covered mountains and surrounded by abundant wildlife in the sea. But even on this continent that looks and feels pristine, a troubling process is underway because of global warming.

The ice on land is melting at a faster rate and large ice sheets are moving toward the ocean more rapidly. As a result, sea levels are rising worldwide. Most of the world’s ice is contained in Antarctica – more than 90 percent. The West Antarctic Ice Sheet, which lies south of the Peninsula, contains enough water to raise sea levels worldwide by more than 20 feet. Part of the ice sheet, the Pine Island Glacier ice shelf, is among the many in Antarctica that are shrinking at an accelerating rate. This has direct consequences for low-lying coastal and island communities all over the world – and for their inland neighbors.

In analyzing the relationship between melting ice and sea level rise, it is important to distinguish between two kinds of ice: the ice on land and the ice floating on top of the sea. When floating ice melts, sea level is not affected, because its weight has already pushed the sea level upward. But the melting of glaciers and ice sheets resting on land does increase sea level rise. So far, the melting of small mountain glaciers and portions of ice sheets in Antarctica and Greenland has been the main contributor to sea level rise from the loss of ice. (As the oceans warm up, their volume naturally expands, and this too has been a contributor to a small portion of the sea level rise that has occurred in the age of global warming).

Read more

Our guest blogger is Emilie Surrusco, Communications Director, Alaska Wilderness League.

Royal Dutch Shell’s quarterly earnings report includes numbers that are almost too big to comprehend – profits of $7 billion in just the last three months, or $2.3 billion in the last month, or $583 million in the last week, or $83 million on Thursday.

I don’t know about you, but I’ll never see the amount of money Shell makes in one day in my entire lifetime. Granted, they are a huge multinational corporation with a budget that is bigger than many nation states. I’m a mere mortal. But with that much money — just in profits alone — you’d think that a multinational corporation like Shell could move mountains. Or at least step up to the challenge of putting together a viable plan to clean up an oil spill in one of the world’s most extreme, remote places — the Arctic Ocean.

Instead, Shell has put forward an oil spill response plan that looks like a fancy cut and paste job from the spill plans of yesteryear. (Remember BP’s Gulf of Mexico spill plan? The one that talked about walrus in Louisiana’s warm, tropical waters? Those are the plans I’m talking about.) It looks to me like Shell didn’t even bother spending a day’s profits on their spill plan for the Arctic. Instead, they’ve piled millions into PR about how great the plan is.

Shell’s latest Arctic P.R. scheme barely costs them a minute’s worth of profits. They recently announced that they will donate $5,000 in Inupiat language preservation grants to an Arctic community school that comes up with the best Inupiat name for one of the drill rigs they plan to use to drill 10 wells in the Arctic’s Chukchi and Beaufort Seas.

But back to Shell’s plan to clean up an oil spill in waters completely covered by sea ice nine months of the year (and partially covered the other three months) — in an environment where temperatures plunge well below zero, there is no sunlight and where more often than not, hurricane force winds cause icebergs the size of apartment buildings to move at 40 mph. The Arctic gives foreboding a new zip code.

Here are some of the highlights of Shell’s plan: Read more

Dr. Jane Lubchenco, a top marine ecologist and senior Obama administration official, is concerned that opening the Arctic to oil and gas development brings unknown risks to human civilization.

In an exclusive interview with ThinkProgress Green, Lubchenco, the administrator of the National Oceanic and Atmospheric Administration (NOAA), discussed the vicious circle of oil and gas greenhouse pollution melting the Arctic sea ice, making it possible for new oil and gas drilling in the region that will melt the ice even faster. Lubchenco had just appeared in a panel on threats to oceans at the Society of Environmental Journalists annual conference on Friday morning, discussing ocean acidification and the unexpectedly rapid decline of Arctic sea ice, both results of greenhouse pollution from burning fossil fuels.

“Less sea ice means greater access to reserves for gas and oil that are there,” Lubchenco said in the TP Green interview, agreeing that “increased production of oil and gas means less sea ice.” When asked whether there are civilizational risks to a world without permanent Arctic sea ice, Lubchenco explained that “what happens in the Arctic doesn’t stay in the Arctic”:

Well, what happens in the Arctic doesn’t stay in the Arctic. It has huge implications for the global system. And one of the reasons people are legitimately concerned about melting of sea ice are the uncertainties associated with the consequences of that for the rest of the planet. We’re entering a no-analogue world here. We’ve never experienced the kinds of changes that we’re seeing now in the Arctic and elsewhere. And we don’t fully understand what the consequences of that are going to be.

Watch the interview:

The United States and other nations with access to the Arctic are taking steps to support the expansion of drilling in regions made accessible by global warming pollution. Although Norway is concerned about the costs of a Deepwater Horizon-like disaster, the government is still encouraging Arctic drilling. In August, Exxon Mobil signed a blockbuster deal with Russia’s Rosneft to explore the Russian reaches of the Arctic ocean for oil. This month, the Department of Interior announced it is moving forward with 500 oil drilling leases sold during the Bush administration for the Chukchi Sea. Last week, the Environmental Protection Agency granted Shell an air permit for exploratory drilling in the Beaufort Sea.

The Arctic Ocean is estimated by the U.S. Geological Survey to have vast reserves of oil and gas. Burning of those fossil fuels would add tens of billions of tons of carbon dioxide to our already overheated atmosphere.

Although NOAA is the nation’s top oceanographic agency, its scientists play only a minor, advisory role in the government’s approval of offshore drilling, which is run by the Interior Department. NOAA plays a larger role in cleaning up after oil spills. Read more

The Arctic ice cap, critical to the stability of the global climate, is melting away. Scientists have recorded new minima in total ice volume and area. Arctic ice volume, estimated by the Polar Science Center at the University of Washington, plummeted to 4275 cubic kilometers by the end of August, well below the 2010 record minimum of 4428 cubic km:

On September 6, Arctic sea ice area fell to 2,917,493 square km, 2000 square km below the previous record of September 7, 2007:

Arctic sea ice extent, as measured by the National Snow and Ice Data Center, has not yet reached its minimum for the year, and it it unknown whether 2007′s record minimum will be broken.