Gretchen Weber

Ice melting in the Arctic, summer 2010

This week, NPR launches a six-part series on, “the changing Arctic,” taking a look at, “what may be the world’s next geopolitical battleground.” Part of that look includes considering the impact of rising temperatures and melting ice, such as freshly-opened strategic waterways and the rush to claim newly-accessible natural resources, like oil and gas deposits.

This focus comes just as MIT releases a new study arguing that the Intergovernmental Panel on Climate Change (IPCC) substantially underestimated the rate at which Arctic sea ice is melting.  The IPCC’s Fourth Assessment Report, released in 2007, forecasts an ice-free Arctic summer by the year 2100.  NPR has created an animated map, showing the Arctic’s loss of summer sea ice for the last 30 years.

NPR's animated Arctic sea ice map.

Take in the companion radio feature and slide show at The California Report weekly magazine. Gretchen’s slide show also appears below.

Photo: Gretchen Weber

During the two weeks I spent in the Arctic at Toolik Field Station this summer, there was a lot of talk about positive feedbacks and how what happens in the Arctic can affect the entire planet. Thawing permafrost, which I explore in my radio piece for The California Report, is cause for some of the greatest concern.

Another is the loss of sea ice. Mean summer temperatures in the Arctic have risen about three degrees Fahrenheit since 1960, and summer sea ice is shrinking more than 11% per decade.  This year ranks third for the minimum Arctic summer sea ice extent since satellite record-keeping began in 1979.   2007 and 2008 hold the records, and 2009 is in fourth place.

Shrinking sea ice matters not just because it’s an indication of warming, but also because it can accelerate it.  Sea ice keeps polar regions cool by reflecting sunlight and heat, which helps moderate the global climate system. When sea ice isn’t there, the sun hits the surface of the Arctic Ocean instead.   The ocean is relatively dark in color, so instead of reflecting 80% of the sunlight, it absorbs 90%.  This heats up the ocean and the Arctic–which, of course, melts more ice.

Another potential feedback scientists are looking at is “shrubification” (try tossing that one into a conversation), but whether it’s a positive or negative feedback remains up for discussion. As the Arctic warms, the boreal forest is moving north and the tundra itself is changing.  The vegetation is shifting to more woody and leafy plants, like birch, and this change could have varying effects on the climate system. On one hand, more leaves mean more photosynthesis, which could mean that the Arctic vegetation could increase its CO2 uptake, acting as a carbon sink by absorbing CO2 from the atmosphere. On the other hand, increased leafy vegetation would make the landscape darker, which would make it absorb more heat, and that warming could potentially offset any effects of increased CO2 uptake.  Also, the woodier, leafier plants can create protected areas where snow can gather, insulating the ground and keeping it warm.  This too, could have warming effects that offset any additional photosynthesis.

“The takeaway is that it’s complicated, and there’s a potential for large positive feedbacks if things continue in the direction they’re going,” said Donie Bret-Harte, a biologist at the University of Fairbanks and the Associate Field Director at Toolik. “And those large positive feedbacks are things that we won’t be able to control.”

Gretchen Weber in the Valley of the Thermokarsts, ready for the mosquitoes. (Photo: Susan Moran)

Bret-Harte said that some scientists are concerned that the Earth may pass a tipping point, and then it won’t matter how much humans recycle their waste or invest in renewable power or reduce their emissions from burning fossil fuels.  The positive feedback loop will take on a life of its own.

“It’s important to remember that these natural feedbacks that come from melting ice and snow and permafrost are not things we can legislate a solution to,” she said.

“If, they start going, and things get warming, and everything starts to thaw, you can’t say, ‘Well, let’s have a treaty and we’ll stop the thawing,’ because that won’t happen.”

One of the positive feedbacks that scientists are most concerned about in the Arctic, is thawing permafrost, which I explore more in-depth in my radio feature.  With that is a slide show from my reporting trip to “The Valley of the Thermokarsts,” a region on the North Slope of Alaska’s Brooks Range, where researcher Andrew Balser digs into the permafrost for clues about why these areas where chunks of permafrost thaw, form where they do.

Coast Guard Cutter Healy. Photo: Petty Officer Patrick Kelley, US Coast Guard

Next week, a NASA team of more than 40 scientists will take to the seas for a five-week expedition in the Arctic to study how changing conditions there are affecting ocean chemistry and ecosystems.  The voyage, NASA’s first dedicated oceanographic research mission, is named ICESCAPE, which stands for “Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment.”  It will take place aboard the US Coast Guard Cutter Healy.

“We’re  trying to address what is the long term impact of climate variability and change, both natural and anthropogenic, on the biogeochemistry and ecology of the Arctic,” said Paula Bontempi, program manager for NASA’s ocean biology and biogeochemistry research program.

The expedition will give scientists a chance to make field observations about the ocean, sea ice, and the atmosphere in regions where researchers often must rely on remote sensing technology for their data.  One main focus of the research will be to observe how changes, such as a substantial decrease in sea ice, may be affecting the ocean’s ability to absorb CO2 from the atmosphere and the consequent effects on ecosystems.

“The Arctic is in the midst of some substantial changes,” said ICESCAPE Chief Scientist Kevin Arrigo of Stanford.  “In the last 10 years, the ice-free season in the Arctic Ocean has increased by about 45 days.  And this has a big impact on organisms in the Arctic that are keyed to these events.”

Arrigo says that the sea ice retreats about 28 days sooner than it did just a decade ago, and advances about 17 days later. He says this change has shifted the timing of food production.  Phytoplankton, the base of the food chain in the Arctic Ocean, are now growing a month earlier than they did in the 1990s, says Arrigo, which could spell a problem for organisms such as the California gray whales, which time their migrations around peak food production.

“Over the years satellite imagery has shown a significant decline in the Arctic ice cover,” said Don Perovich, a research geophysicist at the Cold Regions Research and Engineering Laboratory in Hanover, NH, who is part of the ICESCAPE expedition. “But there’s really more to it than just the ice.  It’s important to remember that sea ice isn’t just some isolated component. It’s part of larger system.”

Sea ice, he said, serves as a barrier between the atmosphere and the ocean, limiting the exchange of heat, moisture and gases; acts as a reflector of sunlight; and is a habitat for a rich marine ecosystem.

“It’s an ecosystem where sea ice and biology are intricately intertwined,” said Perovich. “You can think of the ice and the biology as executing this intricate dance, but it’s a dance where one of the partners has started changing its steps. And that partner is the sea ice cover.”

The 2010 ICESCAPE expedition starts in Dutch Harbor in the Aleutian Islands, will continue across the southern Chukchi Sea and into the Beaufort Sea along Alaska’s northern shelf.  A second expedition is planned for 2011.   NASA estimates the cost of the ICESCAPE project to be $10 million over four years.

The expedition blog has already launched, and will be updated daily once the expedition is underway, according to NASA spokesman Steve Cole.

I’ll be launching my own “Arctic expedition” next week.  Starting June 18th, I’ll be spending two weeks with climate scientists at the Toolik Field Station in northern Alaska, as part of the Logan Science Journalism Program, run by the Marine Biological Laboratory in Woods Hole, MA.   Check back here for periodic dispatches about the science, the landscape, and the impacts of constant daylight on one journalist’s mental state.

To help sort some of this out, I asked for responses from two highly regarded scientists in the field. Here’s a response to the specific reader challenge from Mark Serreze, Director of the National Snow & Ice Data Center, in Boulder, CO:

It is unclear what Mr. Steele is trying to get at with reference to the seasonal cycles in sea ice extent from the AMSR-E data. The AMSR-E data, while valuable, only go back to 2002. Through combining SSM/I and SMMR satellite data with other information sources for earlier years, we have a decent record of Arctic sea ice extent going back to the early 1950s. The relevant issue is the long-term decline in end-of-summer (September) ice extent evident in this record, with the extreme September minima of recent years (represented in the short AMSR-E record) serving as exclamation points. The observed rate of September ice loss exceeds expectations from nearly all climate models.

I also turned to Waleed Abdalati. Now director of the Earth Sciences Observation Center at the University of Colorado, Abdalati is a veteran of the Cryospheric Sciences and Terrestrial Hydrology programs at NASA, and one of the most articulate people I’ve heard speak on the subject of polar ice. He offers the following:

I am not an expert on polar bears, but I do think it is safe to say that
 their primary habitat, the Arctic sea ice, is severely threatened.  I, and 
most of my colleagues believe we are well on our way to an ice-free Arctic
 in summer any time between this decade and the next 40 years.

This
 is because of two things:  1) it will be decades before the ocean has 
finished its response to present-day greenhouse forcing, so the impacts of 
what we’ve done already have not been fully realized; and 2) the loss of
 sea ice is self-compounding: when it starts to shrink, exposing a 
darker more (heat) absorbing ocean underneath, the likelihood of its continued
 shrinking is greater (ice melts, exposes darker ocean, absorbs more heat, 
melts more ice, exposes darker ocean, and so-on).

Of course the flipside
 of this is that as ice starts to grow, it is more inclined to grow, but
 against the backdrop of the increased warming, the former is far more likely 
than the latter. Finally, as thick multi-year ice disappears, it is
 replaced with thinner and younger ice that is more vulnerable to surface 
melt from the atmosphere, bottom melting from sea water, and being carried
 away to lower, warmer latitudes by ocean current and wind.

So back to the polar bears: If their habitat disappears and they are unable 
to hunt seals, their main source of food, they seem to stand little or no
 chance of survival. I am not a wildlife biologist but its hard for me to 
believe they as a population can sustain themselves on land and with only a
 seasonally-present ice cover. In some cases, the fact that they face more
 challenges on sea ice than in the past, has driven them to forage inland,
 creating the illusion in some people’s minds that their populations are 
increasing, because there are more sightings on land. Who knows? Maybe 
they’ll evolve to hibernate in late summer, when there is no ice, and hunt
 the rest of the year.

There is an added effect that doesn’t get much attention.  There was a 
fascinating study by a Canadian Biologist (Ian Stirling) and a sea ice
 expert (Claire Parkinson) [Stirling, I., and C.L. Parkinson. 2006. Possible 
Effects of Climate Warming on Selected Populations of Polar Bears (Ursus
maritimus) in the Canadian Arctic. Arctic 59(3): 261-275.], which suggested 
that the bears are also losing weight, and approaching the weights at which 
they have historically not been able to bear cubs.  So not only is the
population threatened by starvation, the ability to replenish the population
 seems diminished.

I don’t believe we can say anything with absolute certainty,
 so I, myself would not make the statement that the polar bears are doomed–but I will say that the outlook for them, in my view, looks very, very bad.