Into Thin Ice
NATIONAL GEOGRAPHIC | Earth cools when sunlight reflects off Arctic sea ice—which is melting away. Where does that leave us?
To track changes in sea ice, the Norwegian research vessel Lance drifted along with it for five months in 2015, on a rare voyage from Arctic winter into spring. Photo: Andy Isaacson
FIRST PUBLISHED IN NATIONAL GEOGRAPHIC, JANUARY 2016
THE SEA ICE THAT BLANKETS THE ARCTIC OCEAN isn’t the unbroken white mantle depicted in maps. It’s a jigsaw puzzle of restless floes that are constantly colliding, deforming, and fracturing from the force of wind and ocean currents. Last February I stood shivering on the deck of the Lance, an old Norwegian research vessel, as it picked a path through a labyrinth of navigable fractures. A barren white plain of ice and snow extended to the horizon in every direction. The ship’s steel hull shuddered and screeched as it plowed through floating chunks of jagged ice. The Lance was seeking a solid patch of ice to attach to—the last one had shattered—so that it could resume its erratic drift across the frozen sea, charting the fate of Arctic sea ice by going with the floe.
The Norwegians have done this before, more than a century ago, when polar explorer Fridtjof Nansen and the Fram were locked in pack ice for nearly three years during a vain attempt to drift across the North Pole. But the Arctic is a different ocean now. The air above it has warmed on average about 5 degrees Fahrenheit in the past century, more than twice the global average. Much less of the ocean is covered by ice, and much more of that ice is thinner, seasonal ice rather than thick, old floes. A feedback loop with far-reaching consequences has taken effect: As white ice is replaced in summer by dark ocean water, which absorbs more sunlight, the water and air heat further—amplifying the ongoing thaw.
“The Arctic warms first, most, and fastest,” explains Kim Holmén, the long-bearded international director of the Norwegian Polar Institute (NPI), which operates theLance. Climate models predict that by as early as 2040 it will be possible in summer to sail across open water to the North Pole.
Arctic sea ice helps cool the whole planet by reflecting sunlight back into space. So its loss inevitably will affect the climate and weather beyond the Arctic, but precisely how remains unclear. Better forecasts require better data on sea ice and its shifting, uneven distribution. “Most scientific cruises to the Arctic are conducted in summer, and this is where we have the most field data,” says Gunnar Spreen, an NPI sea-ice physicist I met on board the Lance. “The continuous changes that occur from winter into spring are a huge gap in our understanding.”
On the Lance’s five-month mission its rotating crew of international scientists would investigate the causes and effects of ice loss by monitoring the ice across its entire seasonal life cycle—from the time when it formed in winter until it melted in summer.
A few days after photographer Nick Cobbing and I joined the ship by icebreaker and helicopter from Longyearbyen, on the island of Spitsbergen in the Svalbard archipelago—the base for NPI’s Arctic operations—the Lance steamed to 83 degrees north, just west of Russian territory. The scientists singled out a half-mile-wide floe of predominantly seasonal ice that they hoped to study. The crew tethered the vessel to the floe with nylon ropes attached to thick metal poles driven into the ice. They shut off the main engine. Isolated and in near darkness, we began our wayward drift and our month-long shift in the ice desert.
Like homesteaders, the scientists established camps on the floe, pitching tents and laying electric cables. Physicists like Spreen mapped the ice topography with lasers and recorded the thickness and temperature of the snow on top. Oceanographers bored a hole through the ice to gather data about the water and the currents. Meteorologists erected masts carrying instruments to collect weather data and measure greenhouse gases. Biologists searched for ice algae, which look like dirt and live on the underside of the ice and in the channels of trapped brine left after newly formed sea ice expels salt. In a few weeks, after the returning sun cast aside the cloak of polar night and began filtering through the melting floe, the scientists would watch the ecosystem awaken.
Temperatures regularly plunged to 30 degrees below zero Fahrenheit. Scientists had to contend with numb fingers, snapped cables, and crippled electronic instruments, along with the danger of roving polar bears. “This is really extreme science,” one researcher said.
Photo: Andy Isaacson
IN 2007 THE UN INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC) warned that the impacts of climate change in the Arctic over the next century “will exceed the impacts forecast for many other regions and will produce feedbacks that will have globally significant consequences.” Nearly a decade later this grim forecast is already being borne out. Probably no region has been more affected by climate change than the Arctic. Permafrost is thawing, and the land is greening, as tree lines creep north and shrubs and grasses invade the tundra. Certain populations of polar bears, walruses, and caribou have suffered significant declines. National Oceanic and Atmospheric Administration (NOAA) oceanographer James Overland says, “The Arctic really is the canary showing that climate change is real.”
Since 1979, when satellite records began, the Arctic has lost more than half its volume of ice, which has diminished in both overall area and thickness. The frozen area shrinks to its annual minimum in September, at summer’s end. In September 2012 its extent was just half the average during the 1980s and ’90s. The maximum ice extent in winter, usually reached in March, also is declining, though at a slower rate; its average thickness has decreased by half. What was once mostly a layer of 10- to 13-foot-thick ice floes that lingered for years—perennial ice—has given way to large tracts of thinner, less reflective ice that forms and melts during a single year. Sea-ice coverage has always fluctuated naturally, but there’s little doubt among scientists that man-made greenhouse gases are now accelerating its decline. “Old, thick sea ice was a global reservoir for cold, but that is now changing,” Overland says.
An entire ecosystem is melting away. The loss of sea ice may take a toll on some of the photosynthesizing organisms that fuel the marine food chain—single-celled algae that live under the ice and bloom in the spring when the light returns. Changes in the magnitude and timing of these blooms, as winter ice retreats faster and earlier, may throw off the life cycle of tiny, fatty zooplankton called copepods, which eat the algae and are in turn eaten by arctic cod, seabirds, and bowhead whales. For marine mammals such as the polar bear, Pacific walrus, and ringed seal, the loss of hundreds of thousands of square miles of sea ice has already been devastating. “It’s like someone took the floor out from under you,” says Kristin Laidre, a polar scientist at the University of Washington.
The assumption is that later this century, without a home field, these animals will simply lose all competitive advantage. Killer whales, for example, are likely to replace polar bears as the top marine predators, as bears retreat to the dwindling remnants of summer sea ice. Though polar bears sometimes spend time on land, where lately a few have been hybridizing with grizzlies, Ian Stirling of the University of Alberta, a leading polar bear expert, dismisses any notion that they could survive long-term on land as “wishful thinking.” Ice-free conditions are likely to draw in other competitors—zooplankton (maybe less fatty and nutritious ones), fish, seals—from more temperate waters.
Ice loss is also making the Arctic even more vulnerable to ocean acidification, another effect of rising atmospheric carbon dioxide. Cold water absorbs more CO₂ than warm water does, and more cold water is now open to the air. As the water acidifies, it loses carbonate. Within the next 15 years it may no longer contain enough for animals such as sea snails and Alaska king crabs to construct and maintain their calcium-carbonate shells.
The upshot of all this, as Stirling bluntly puts it: “The Arctic marine ecosystem as we know it now will no longer exist.”
Photo: Andy Isaacson
WARMER AIR ABOVE THE OCEAN BASIN IS PROJECTED TO SPILL DOWN over the surrounding coasts of Russia, Alaska, and Canada, causing feedback effects as far as 900 miles inland, including accelerated melting of the Greenland ice sheet and large emissions of carbon dioxide and methane from thawing tundra. IPCC models forecast that the total loss of summer sea ice may in itself cause one-third of the warming of the Northern Hemisphere and 14 percent of total global warming by the end of the century.
How a rapidly warming Arctic will influence weather across the hemisphere is a bit hazier. Atmospheric scientists Jennifer Francis at Rutgers University and Steve Vavrus at the University of Wisconsin have suggested that people in the continental United States already may be feeling the effects of melting Arctic sea ice—especially in the past two winters in the east, which made “polar vortex” household words.
The polar vortex is the mass of cold air that’s normally confined over the Pole by the polar jet stream—the high-altitude, fast-moving torrent of air that snakes around the Pole from west to east. The jet stream draws most of its energy from the contrast in temperature and pressure between the frigid air to its north and the warmer air to the south. As sea-ice loss amplifies the warming in the Arctic, the Francis theory goes, that contrast is reduced, weakening the jet stream’s westerly winds. It becomes a lazier, more sinuous river, with large meanders that extend far to the south and north. Because the meanders advance slowly across the map, whatever weather they enfold persists for a long time. During the past two winters the wavier pattern allowed Arctic air and extreme snow to beset New England and drought to linger over California. The melting Arctic may be affecting weather elsewhere too. Korean researchers have linked extreme winters in East Asia to air-circulation changes caused specifically by ice loss in the Barents-Kara Sea.
It’s a neat theory, but parts of it remain “fuzzy,” Francis admits. Also, many researchers who study atmospheric dynamics aren’t buying it. A more plausible explanation for the wavier jet stream and the southward excursions of the polar vortex, some of them argue, is the influence of the tropical Pacific, which is a far more powerful source of heat than the Arctic. It will take years of data gathering and modeling to settle the debate.
In any case, as the warming of the planet continues, cold spells of any kind will become less common. Even if sharp limits on greenhouse gas emissions are adopted over the next 20 years, the decline of sea ice will continue for decades. “We’re on a one-way trip and not going back,” says Overland. A further rise of 4 degrees Celsius (7.2 degrees Fahrenheit) in the Arctic is all but assured by mid-century, he says, enough to keep the ocean ice free for at least two months of the year, enough to change the seasons there—“enough to affect everything.”
Photo: Andy Isaacson
IN LATE JUNE, DURING THE FINAL PHASE OF THEIR EXPEDITION, the scientists aboard theLance awoke to discover that the latest ice floe they’d attached to was disintegrating too. They scrambled to salvage their gear before it became flotsam. It was time to pack up anyway. The vessel by that point had spent 111 days in the ice, tethered to different floes for several weeks at a time—logging altogether some 4,000 nautical miles across the Arctic. Polar bears had crossed its path, sometimes pausing to play with the scientists’ strange-looking electronic instruments. Storms had bulldozed huge blocks of ice high against the ship, elevating it above the surface. The Lance’s crew had bested the researchers in a soccer match on the floe. Over the next couple of years the 68 scientists involved will be hunkered in their warm labs, making sense of all the data they gathered.
One morning in March, under a dusky blue sky, I had joined Gunnar Spreen and another NPI researcher, Anja Rösel, on one of their periodic forays to measure changes in the ice floe’s thickness. We each wore insulated armor—jumpsuit, balaclava, goggles, gloves, mittens over the gloves. The scientists brought along a snow-depth probe, a GPS device, and an orange plastic sled carrying the ice-thickness instrument, which works by inducing an electric current in the seawater below. I carried a flare gun and a .30-06-caliber rifle: bear protection. Following a mile-long path staked by bamboo poles, we trudged over dunelike snowdrifts and pressure ridges—slabs of sea ice pushed up by colliding floes—that looked like crumbling stone walls. Every few feet Spreen stopped and plunged the depth gauge into the snowpack until it beeped to indicate that the measurement was complete.
Arctic warming seemed an abstract concept that day—I couldn’t really feel my toes—but across the icescape, Spreen saw evidence of change. “This is an unusual amount of snow,” he noted. Two feet of it lay beneath our moon boots, twice the amount in a typical year. One data point doesn’t make a trend, but this one was consistent with model forecasts: As sea ice shrinks, the extra heat and water vapor released from the open water into the lower atmosphere should generate more precipitation.
More snow falling on a glacier on land would be a good thing, because that’s how glaciers grow—by accumulating layers of snow so thick that the stuff at the bottom gets compressed into ice. But sea ice forms when cold air freezes seawater, and snow falling on top of it acts as an insulating blanket that slows the growth of the ice. As it happened, two weeks after my walk with Spreen, the National Snow and Ice Data Center in Colorado announced that Arctic sea ice had already reached its maximum extent for the winter in late February—much earlier than usual. It was the lowest maximum the satellites had ever recorded.
Photo: Andy Isaacson
In a Changing Antarctica, Some Penguins Thrive as Others Suffer
NEW YORK TIMES | Global warming and the Adélie penguin.
Adélie penguins in Cape Royds, home to the southernmost colony of penguins. Credit: Andy Isaacson
FIRST PUBLISHED IN THE NEW YORK TIMES, MAY 9, 2011
ROSS ISLAND, ANTARCTICA— Cape Royds, home to the southernmost colony of penguins in the world, is a rocky promontory overlaid with dirty ice and the stench of pinkish guano. Beyond the croaking din of chicks pestering parents for regurgitated krill lies the Ross Sea, a southern extension of the Pacific Ocean that harbors more than one third of the world’s Adélie penguin population and a quarter of all emperor penguins, and which may be the last remaining intact marine ecosystem on Earth.
The penguin colony is one of the longest-studied in the world. Data on its resident Adélie penguins was first acquired during the 1907-9 expedition of Ernest Shackleton, the eminent British explorer, whose wooden hut stands preserved nearby. “This is penguin nirvana,” David Ainley, an ecologist with the consulting firm H. T. Harvey and Associates who has been studying Ross Sea penguins for 40 years, said on a morning in January. “This is where you want to be if you’re a pack ice penguin.”
Of the species that stand to be most affected by global warming, the most obvious are the ones that rely on ice to live. Adélie penguins are a bellwether of climate change, and at the northern fringe of Antarctica, in the Antarctic Peninsula, their colonies have collapsed as an intrusion of warmer seawater shortens the annual winter sea ice season.
In the past three decades, the Adélie population on the peninsula, northeast of the Ross Sea, has fallen by almost 90 percent. The peninsula’s only emperor colony is now extinct. The mean winter air temperature of the Western Antarctic Peninsula, one of the most rapidly warming areas on the planet, has risen 10.8 degrees Fahrenheit in the past half-century, delivering more snowfall that buries the rocks the Adélie penguins return to each spring to nest — and favoring penguins that can survive without ice and breed later, like gentoos, whose numbers have surged by 14,000 percent.
The warmer climate on the Antarctic Peninsula has also upended the food chain, killing off the phytoplankton that grow under ice floes and the krill, a staple of the penguin diet, that eat them, by as much as 80 percent, according to a new study published this month in The Proceedings of the National Academy of Sciences.
But in the Ross Sea a reverse trend is occurring: Winter sea ice cover is growing, and Adélie populations are actually thriving. The Cape Royds colony grew more than 10 percent every year, until 2001, when an iceberg roughly the size of Jamaica calved off the Ross Sea ice shelf and forced residents to move 70 kilometers north to find open water. (The iceberg broke up in 2006, and the colony of 1,400 breeding pairs is now recovering robustly.) Across Ross Island, the Adélie colony at Cape Crozier — one of the largest known, with an estimated 230,000 breeding pairs — has increased by about 20 percent.
Climate change has created a paradise for some pack ice penguin colonies and a purgatory for others, but the long-term fate of all Adélie and emperor penguins seems sealed, as relentless warming eventually pulls their rug of sea ice out from under them. Some scientists attribute the recent sea ice growth in the Ross Sea to the persistent ozone hole, a legacy of the human use of chlorofluorocarbons that cools the upper atmosphere over the continent, increasing the temperature difference with the lower atmosphere and equator, and over the last 30 years has delivered significantly brisker westerly winds in the summer and autumn. The warming of Earth’s middle latitudes is having a similar effect, increasing that temperature difference and sending stronger winds that push sea ice off the coast and expose pockets of open water, called polynyas, that give nesting Adélie penguins easier access to food.
Meanwhile, consumers’ appetite for Chilean sea bass (Antarctic and Patagonian toothfish) may also be benefiting Ross Sea penguins, as fishing fleets from southern nations converge on one of the last remaining refuges of the fish (Dissostichus mawsoni). A fishery in the Ross Sea that opened in 1996 and was certified sustainable in December by the Marine Stewardship Council, could ultimately serve Adélie penguins by reducing competition for Antarctic silverfish (Pleuragramma antarcticum), a sardine-size fish that the penguins and toothfish enjoy. Dr. Ainley and colleagues have reported seeing fewer killer whales in the southern Ross Sea since 2002. The whales feed on toothfish, and fewer sightings suggest that the fishery is already altering the ecosystem.
Researchers witnessed Ross Sea penguin colonies thrive during the 1970s when commercial whaling removed 20,000 Antarctic minke whales, also a food competitor of Adélies, from the penguins’ wintering area. Adélie populations eventually leveled off after 1986, after an international moratorium on whaling began (and remained static until the more recent influences of climate change). Japanese whaling of minkes resumed right after the moratorium was instituted, purportedly for science, a claim that conservation groups dispute and that has incited a confrontation in the Ross Sea between the Japanese fleet and the Sea Shepherd Conservation Society, an antiwhaling vigilante group.
“It has become difficult to separate whether the increase is due to climate change or fewer toothfish,” Dr. Ainley said. “Both factors seem to be working at the same time.”
On a chilly morning in January, the Cape Royds colony was clustered across the dark volcanic rock in crèches: month-old chicks, furry and pear-shaped with tummies full of krill, huddled near their parents as adolescent penguins, still too young to breed, acted “like teenagers trying to figure out the social scene,” in Dr. Ainley’s assessment. Their cuddly appearance is misleading, it turns out, a projection of human sentiment. “They’re really nasty to one another,” Dr. Ainley said, “and if you try to pick one up you’ll have your hands full.”
Climate models predict that the winds and sea ice will continue to increase in the Ross Sea for the next 30 to 40 years, at which time the region is expected to experience a tipping point, as rising temperatures and the waning effect of the ozone hole, now getting smaller, transform the climate into the kind now seen in the Antarctic Peninsula.
Already, that process is under way. The average summer temperature at McMurdo Station, the American research base on Ross Island, has inched up 2.7 degrees Fahrenheit in the past 30 years, records show, more than the global average. Scientists conducting longterm studies of lakes in the McMurdo Dry Valleys, Antarctica’s largest ice-free area, report that after a decade of cooling, some lakes in the Taylor Valley are now gaining heat. During this past research season the scientists recorded unprecedented lake levels caused by higher glacial runoff.
On Beaufort Island, north of Ross Island, glaciers have retreated over the rocky coastline farther than they have in 30,000 years, scientists estimate, a time before the last ice age. The receding ice has opened up more nesting habitat for the resident Adélie penguin colony, which has expanded to 55,000 breeding pairs from 40,000 in the last decade.
As the sea ice retreats, researchers expect that Adélie penguins living in the Ross Sea will be forced to shift their range farther south toward the pole. In a study between 2003 and 2005, Dr. Ainley and colleagues from PRBO Conservation Science, Stanford University, NASA and the British Antarctic Survey used geolocation sensor tags to track penguins from Cape Royds and Cape Crozier to better understand their migration patterns. Published last year in the journal Ecology, the study revealed how the penguins depart their nesting grounds in February, at the end of the austral summer, and head north on foot and ice floes to flee the protracted darkness of the Antarctic winter. They appear to stop on the sea ice about 300 miles from the boundary with open water, where they stay to forage and fatten before doubling back south to their island breeding sites ahead of the creeping northern night — an 8,000-mile journey.
By carbon-dating mummified penguin remains, researchers have been able to construct a long-term history of the Adélie in Antarctica, indicating that throughout the last ice age penguins changed their migration routes and colony locations in response to advances and retreats of the sea ice. However, their range appears to have never extended farther south of where it is currently, for the simple reason that Adélie penguins appear to need light — if only twilight — to forage and navigate, and as comfort against predators.
“Emperor and Adélie penguins have an obligatory association with sea ice,” Dr. Ainley said. “As the sea ice goes, these species will go.” The Ross Sea is projected to be the last place on Earth where sea ice will endure. But as the annual winter sea ice boundary retreats farther south, pack ice penguins may ultimately find themselves trapped behind a curtain of polar night for which they have no hardwired strategy.
Indeed, Dr. Ainley speculates, Adélie penguins face possible extinction not merely by a loss of habitat — but by an unshakable fear of darkness.