Antarctica and the Arctic
09 Feb 2016:
Ice-Free Arctic Trade Route
Unlikely For Decades to Come, Study says
Despite the impact climate change is having on Arctic sea ice, it will be decades before big cargo ships will be able to take an ice-free shortcut
Russian tanker making its way through ice.
across the Arctic Ocean, according to a new report from the Arctic Institute
. In recent years, countries have been vying for access to possible Arctic shipping lanes in the belief that use of the passage was more imminent and would contribute to shorter travel times and associated cost savings
. But given the Arctic’s short sailing season, continuing treacherous ice conditions, the high costs associated with armoring cargo ships to withstand the ice, as well as low fuel prices, the Institute predicts that such crossings won’t become commercially viable until at least 2040. Until that time, shipping between Europe and Asia will continue to use the Suez Canal. Arctic shipping has decreased in recent years, from 1.3 metric tons in 2013 to 300,000 tons in 2014.
18 Nov 2015:
Icelandic Ice Cap Gains Mass for
First Time in Two Decades, Researchers Say
An Icelandic ice cap known as Hofsjökull, shown in this NASA satellite image, has gained mass for the first time since 1993,
Iceland's Hofsjökull ice cap
measurements taken last month. All ice caps in Iceland had been retreating rapidly and losing volume since 1995, due to decreasing precipitation and rising temperatures. Hofsjökull’s resurgence this year is the result of abundant winter precipitation and cooler than normal summer temperatures, explained Thorsteinn Thorsteinsson, a glaciologist at the Icelandic Meteorologial Office. Last winter, snowfall in the region of the ice cap was 25 to 60 percent thicker than the 1995-2014 average. Cool northerly winds slowed Hofsjökull’s summer melt rate, contributing to the positive measurements obtained last month.
13 Oct 2015:
Antarctic Ice Shelves Face
Major Threat If CO2 Emissions Keep Rising
A new study says that many of Antarctica’s floating ice shelves — which play a key role in holding back vast amounts of land-based ice — could become highly unstable
later this century if greenhouse gas emissions are not sharply reduced. An international team of researchers, reporting in Nature Geoscience
, said that surface melting of Antarctica’s ice shelves could reach the point where many could disintegrate. Such surface melting has already led to the collapse of numerous ice shelves along the rapidly warming Antarctic Peninsula. The study said that surface melting of the continent’s ice sheets would double by 2050
under both intermediate- and high-emissions scenarios. After that, the fate of the ice shelves diverges sharply depending on emissions levels, with a high-emissions scenario leading to surface melting equaling or exceeding intensities associated with ice shelf collapse. Loss of the ice shelves could lead to major increases in sea level as inland glaciers flow to the sea, scientists say.
05 Oct 2015:
Icelandic Seafood Giant
May Be Involved in Endangered Whale Hunt
Iceland’s controversial annual hunt of fin whales — classified as "endangered" by the International Union for Conservation
of Nature — ended with a catch of 155 fin whales, the largest slaughter since the 1986 moratorium on commercial whaling, reports the London-based advocacy group Environmental Investigation Agency (EIA). The EIA and the Animal Welfare Institute obtained evidence
revealing the ongoing involvement of international seafood giant HB Grandi — a Reykjavík-based company with an annual income of roughly $230 million (as of 2011) — in the whaling business, despite its claims to the contrary. HB Grandi is Iceland’s largest seafood company and its CEO has repeatedly insisted that the company “is not involved in whaling and never has been.” Despite the international moratorium, Iceland recently has allowed commercial whaling and has shipped whale products to Japan.
28 Sep 2015:
Shell Ends Arctic Oil and Gas
Exploration Bid for Foreseeable Future
Shell Oil has announced
that it will stop its controversial exploratory drilling for oil and gas in Arctic waters for the foreseeable
Shell's Polar Pioneer rig as it left Seattle for the Arctic
future, saying in a statement that the reserves it had discovered were not “sufficient to warrant further exploration.” Shell began operating its first exploration well on July 30, 2015, in the Chukchi Sea off the northwestern coast of Alaska. But the company reported that although it had found indications of the presence of oil and gas, the reserves in the basin where they were drilling were, in the words of one company official, "clearly disappointing." Under Shell's federally approved exploration plan, all rigs and support vessels must leave the Chukchi Sea before the end of October. Environmental groups hailed Shell's announcement.
22 Sep 2015:
Antarctic Seafloor Life Is
Locking Away a Lot of Carbon, Study Says
The loss of sea ice over Antarctic waters has caused certain forms of life to flourish on the seafloor, and those underwater communities
An Antarctic icefish swimming over bryozoans
are acting as important and unexpected carbon sinks, according to research published in the journal Current Biology
. Based on studies of West Antarctic bryozoans — aquatic invertebrates sometimes referred to as "moss animals" — researchers have found that those and other seafloor organisms could play important roles in accumulating and burying carbon, removing it from the atmosphere for an extremely long time. The researchers calculate that growth of the bryozoans has nearly doubled over the past 20 years, with the animals taking in more than 200,000 tons of carbon per year since the 1980s. Accounting for other undersea species, the researchers suggest that roughly 3 million tons of carbon are sequestered each year, equivalent to nearly 200 square miles of tropical rainforest.
18 Sep 2015:
Genes of Greenlanders Preserve
Evidence of Ancient Arctic Adaptation
The DNA of modern-day Greenlanders shows how their Inuit forefathers adapted to the harsh Arctic environment they called home
80% of Greenlanders identify as Inuit.
for thousands of years, according to findings published in the journal Science
. The Arctic is an extreme environment, characterized by a cold climate and sparse vegetation. The typical diet of Greenlanders — and their ancient ancestors — is made up primarily of proteins and fats from fish and marine mammals, and carbohydrate and vegetable consumption is minimal. By collecting genetic information from 4,500 modern Greenlanders, researchers determined which genes have changed the most over the roughly 20,000 years since Greenlanders' most ancient Inuit ancestors separated from their nearest East Asian relatives, the Han Chinese. The genetic changes the researchers identified show that through natural selection the Greenlandic Inuit's genetic makeup evolved in a way that enabled them to efficiently metabolize the fatty acids from fish and to live with few carbohydrates and vegetables.
In Northern Canada Peaks, Scientists
Are Tracking Impact of Vanishing Ice
Earlier this month, a team of Canadian scientists braved a cold-weather thunderstorm, snow, rain, and high winds to spend a week working on the last extensive icefield in the interior of the Northwest Territories. Accompanying them was Yale Environment 360
contributor Ed Struzik, who reports on the trip and the importance of the research team’s investigations. The group worked on the Brintnell/Bologna icefield, which has shrunk by more than a third over the last three decades and continues to melt at a rapid clip. The scientists hope to determine how the melting of these glaciers and the loss of snowpack in the surrounding mountains might affect the region’s ecology and rivers, including the huge Mackenzie River, Canada’s largest.
18 Aug 2015:
How West Antarctica Could Melt
If Greenhouse Emissions Continue to Rise
An international team of scientists has developed the first comprehensive, high-resolution model depicting
how rapidly the West Antarctic Ice Sheet (WAIS) could melt
if greenhouse gas emissions are not brought under control. The study projects that under a high-emissions scenario, the WAIS could lose 80,000 cubic kilometers (19,000 cubic miles) of ice by 2100, increasing sea levels by 8 inches. By 2200, the WAIS could lose 48,000 cubic miles of ice, raising sea levels by a total of 23 inches, the study says. The video shows projected ice loss in the major glaciers feeding into the massive Amundsen Sea Embayment over the next three centuries. The red and orange colors depict the speed of glacial retreat in meters per year. The WAIS is only a fraction of the size of the East Antarctic ice cap, but if the entire WAIS were to melt, global sea levels would rise by roughly 16 feet.
12 May 2015:
Unique Stretch Marks Show
Greenland Ice Accelerating Toward Sea
The Greenland ice sheet is accelerating as it flows toward the ocean, and the unique markings visible in this photograph
Crevassing in Greenland ice
are one piece of evidence
demonstrating its rapid movement. Captured as part of NASA's Operation IceBridge
, which is wrapping up its seventh season of Arctic observations, this image details heavy crevassing near the coast of Melville Bay in northwestern Greenland. These fissures are essentially stretch marks on the ice, NASA researchers say. Ice sheets in Greenland and Antarctica are losing mass at an unprecedented rate of 500 cubic kilometers per year — enough ice to cover the Chicago metropolitan area with a layer of ice 600 meters thick — according to
one recent report.
16 Apr 2015:
Researchers Discover New
Source of Methane in the Arctic Ocean
A large reservoir of methane — a greenhouse gas many times more potent than carbon dioxide — was recently discovered on
Knipovich Ridge in the Arctic Ocean
Knipovich Ridge in the central Arctic Ocean, according to
research published in the journal Geology
. The methane in this deposit is locked up in icy crystals of water and gas called hydrates, and it was produced by abiotic geological processes rather than by microbes breaking down organic matter, as most methane is, the authors explain. Until now, scientists had not known that hydrates could contain this type of methane. "Up to 15,000 gigatons of carbon may be stored in the form of hydrates in the ocean floor, but this estimate is not accounting for abiotic methane," said co-author Jürgen Mienert. "So there is probably much more."
09 Apr 2015:
Melting Arctic Permafrost
To Cause Massive but Gradual CO2 Release
A comprehensive new study of the potential climate change impacts of melting Arctic permafrost says that a vast amount of carbon dioxide will be released from thawing permafrost but that it will seep out gradually,
rather than in an abrupt “carbon bomb.” Working since 2011, a group of 17 Arctic permafrost scientists studied the rate at which permafrost is thawing and the resulting release of CO2. The scientists concluded that Arctic permafrost has undergone a stunning degree of warming, rising from an average of 18 F three decades ago to 28 F today. As permafrost continues to melt, it will release an amount of carbon roughly equal to the carbon released from current rates of deforestation, the study said. The study, published in the journal Nature
, said the CO2 release from thawing permafrost will be prolonged but gradual, giving society time to adapt to rising seas and other impacts of a warming climate.
12 Mar 2015:
Bubbling From Melting Glaciers
Makes Fjords Noisiest Places in Oceans
Bubbles gushing from melting glaciers and their icebergs make fjords the noisiest places in the oceans, according to
research published in Geophysical Research Letters
. Researchers used underwater microphones to record noise levels in three bays where glaciers flow into ocean fjords and icebergs calve from glaciers. They found that average noise levels from bubbles in these fjords exceeded those generated by all other sources, including weather, wildlife, and machines such as ships and sonar devices. Glacial calving contributed some of the noise, but the constant melting and bubbling was the real culprit, the researchers said. Their findings raise questions about how the underwater noise in the fjords — which are foraging hotspots for seabirds and marine mammals and important breeding habitat for harbor seals — will affect animals as climate change further increases melting rates.
11 Mar 2015:
Warming To Sharply Increase
For Remainder of 21st Century, Paper Says
Within a decade, the earth — and particularly the northern hemisphere — will begin warming at rates unprecedented in the last 1,000 to 2,000 years, according to new research
in the journal Nature Climate Change
. Examining the rate of temperature increases in 40-year intervals over the past 2,000 years, the scientists concluded that temperatures had fluctuated up or down by about 0.2 degrees F over each interval. In the past 40 years, however, warming has approached 0.4 degrees F per decade. And beginning in 2020, temperatures could start to rise by 0.7 degrees F per decade and continue at that rate until at least 2100. Warming will be especially pronounced in the Arctic, where temperatures are expected to soar by 1.1 degrees F by 2040. The scientists warned that such greenhouse gas-driven warming is moving the planet into an unstable climatic state.
02 Mar 2015:
Emperor Penguins Had Few
Refuges During Last Ice Age, Study Finds
The Ross Sea and certain other Antarctic waters likely served as refuges for the three emperor penguin populations that
survived during the last ice age, when large amounts of ice made much of the rest of Antarctica uninhabitable, according to a new study
published in the journal Global Change Biology
. The findings suggest that extreme climatic conditions on the continent during the past 30,000 years created an evolutionary "bottleneck" that is evident in the genetic material of modern-day emperor penguins, a species known for its ability to thrive in icy habitats. But during the last ice age, the Antarctic likely had twice as much sea ice, the researchers say, leaving only a few locations for the penguins to breed — distances from the open ocean (where the penguins feed) to the stable sea ice (where they breed) were too great. The three populations that did manage to survive may have done so by breeding near areas of ocean that are kept free of sea ice by wind and currents, the researchers suggest.
As Arctic Ocean Ice Vanishes,
Questions About Future Fishing
With the steady retreat of sea ice in the Arctic Ocean opening up vast areas of this long-frozen marine basin, a key resource
A Russian fishing vessel trawls the Arctic Ocean.
issue is now emerging: the future of fisheries, especially in central Arctic waters. What species are migrating into the region as sea ice disappears? And could the heart of the Arctic Ocean sustain a commercial fishery in the coming decades? These issues were central to a discussion at a recent conference on the fisheries of the central Arctic Ocean. With more southerly fish species migrating into warmer and increasingly ice-free regions of the Arctic Ocean, officials from the U.S. and Canada say it’s important to negotiate an international agreement on fishing before allowing fisheries to open.
Read the article.
22 Jan 2015:
Draining of Greenland Lakes
Signals Massive Melting, Researchers Say
Researchers have discovered
craters left behind when two lakes under the Greenland ice sheet rapidly drained recently — an indication
Crater left after a Greenland lake drained.
that a massive amount of meltwater has started overflowing the ice sheet's natural plumbing and is causing "blowouts" that drain lakes away, they say. One of the two lakes once held billions of gallons of water and emptied to form a mile-wide crater in just a few weeks, researchers report in the journal The Cryosphere
. The other lake, described this week in the journal Nature
, was two miles wide and has filled and emptied twice in the last two years. The researchers suspect that as more meltwater reaches the base of the ice sheet, natural drainage tunnels along the Greenland coast are cutting further inland. The tunnels carry heat and water to areas that were once frozen to the bedrock, potentially causing the ice to melt even faster.
06 Jan 2015:
Penguin Watch Projects Asks
Citizen Scientists to Monitor Birds' Habits
, a citizen science project launched by researchers from the University of Oxford in the U.K., is enlisting the
Group of Gentoo penguins
public's help in counting penguins in some 175,000 photos from locations across the Southern Hemisphere. Researchers are monitoring five penguin species — Gentoo, Chinstrap, Adelie, Rockhopper, and King penguins — and recording information on the number of adults, chicks, and eggs, as well as their winter behavior, breeding success, and travel habits. The project is especially useful for monitoring penguins' winter behavior, for example, because it's logistically difficult for the researchers to visit these locations in winter, they say
, and the images are far too numerous for researchers to view on their own. Understanding how the penguins live day-to-day should help shed light on how the penguins will respond to an increasingly volatile climate, the team says.
29 Dec 2014:
The Arctic Is Absorbing
More and More Sunlight, NASA Images Show
The Arctic has been absorbing significantly more sunlight since the year 2000, according to NASA satellite data
Changes in absorption of sunlight in the Arctic
a trend that mirrors the steady decrease in Arctic sea ice during that same period. These maps show changes in the amount of solar radiation absorbed over the Arctic from 2000 to 2014, as well as changes in sea ice cover during the same period. As sea ice cover declines and more dark ocean is exposed to the sun's rays, that decreases the reflectivity, or albedo, of the ocean's surface, meaning more heat is absorbed. Shades of red depict areas absorbing more sunlight and areas with less ice cover. The Arctic's rate of absorption has increased by 5 percent every June, July, and August since 2000. No other region on the planet has shown significant changes in albedo during that time, researchers say.
29 Oct 2014:
Weather and Climate Key in Weights of Penguin Chicks, Researchers Say
Local weather and large-scale climate trends have the largest impact on the weights of Adélie penguin chicks
An adult Adélie penguin feeds its chick.
— not food availability — according to
researchers at the University of Delaware. Adélie penguins are native to the West Antarctic Peninsula, and their habitat is warming faster than most other parts of the planet. Looking at records dating back to 1987, scientists found that year-to-year changes in local weather — including wind speed, temperature, rain, and humidity — could cause chicks’ weights at the time they leave their nests to fluctuate by up to 7 ounces. That’s often the difference between a surviving and non-surviving chick, the researchers say. Biologists previously thought that food sources and parenting played the largest role in chicks’ health, but these findings
suggest that exposure to elements is more important. The study "calls into question what happens to an ecosystem when you change climate quickly," principal investigator Matthew Oliver said.
21 Aug 2014:
Antarctica and Greenland
Losing Ice at Fastest Rate Ever Recorded
Ice sheets in Greenland and Antarctica are losing mass at an unprecedented rate of 500 cubic kilometers per
year — enough ice to cover the Chicago metropolitan area with a layer of ice 600 meters thick — according to
German researchers. Using data from the European Space Agency's CryoSat 2 satellite from 2011 to 2014, the team created the most detailed maps to date of ice elevations across Antarctica and Greenland, accurate to a few meters in height. The results reveal that Greenland alone is losing ice volume by about 375 cubic kilometers per year, doubling since 2009, the scientists report. Ice loss in the West Antarctic Ice Sheet has increased by a factor of three over the same period. Combined, the two ice sheets are thinning at the highest rate observed since altimetry satellite records began about 20 years ago, the study found. Data show that East Antarctica is gaining ice volume, but at a moderate rate that doesn’t compensate the losses on the continent's other side.
30 Jun 2014:
Antarctica's Emperor Penguins
To Be in Serious Decline By 2100, Study Says
Antarctica's Emperor penguins are facing dramatic declines by the end of the century and should be given endangered species status because of the threats posed
Sea ice loss threatens Emperor penguins.
by climate change, according to
an international group of scientists. If sea ice declines at the rates projected by current climate models, at least two-thirds of the colonies will likely shrink by more than 50 percent by 2100, the researchers report in Nature Climate Change
. That conclusion follows a 50-year study in eastern Antarctica of Emperor penguins, an iconic Antarctic species with 45 known colonies. Emperor penguins' survival is highly dependent on sea ice concentrations because they breed on the ice, and too little sea ice reduces the habitat for krill, a critical food source for the penguins. Granting the species protected status under the U.S. Endangered Species Act will provide tools for improving fishing practices of U.S. vessels in the Southern Ocean and potentially for reducing CO2 emissions in the U.S. under the Clear Air Act, the researchers say.
16 Jun 2014:
Skyscraper-Size Ice Structures
Discovered at Base of Greenland Ice Sheet
Melting and refreezing at the base of the Greenland ice sheet has created massive, complex structures the height of skyscrapers and the width of Manhattan, according to
research published in Nature Geoscience
The hidden formations more than a mile below the surface stand in stark contrast to the nearly flat, smooth exterior of the ice sheet and may accelerate its flow toward the sea, researchers say. Scientists had previously interpreted the irregular topography at the base of the ice as hills or mountains, but ice-penetrating radar revealed that the structures were made of ice rather than rock. Scientists from Columbia University explained that as meltwater at the bottom refreezes over hundreds or thousands of years, it radiates heat into the surrounding ice sheet, making it pick up its pace as the ice becomes softer and flows more easily. Greenland's glaciers appear to be moving more rapidly toward the sea as climate warms, but it's unclear how the refreezing process will influence this trend, researchers said.
20 May 2014:
Widespread Greenland Melting
Due to Forest Fires and Warming, Study Says
Rising temperatures and ash from Northern Hemisphere forest fires combined to cause large-scale surface melting of the Greenland ice sheet in 2012, an
echo of a similar event that occurred in 1889, a new study
finds. The massive Greenland ice sheet — the second largest ice body in the world after the Antarctic ice sheet — experiences annual melting at low elevations near the coastline, but surface melt is rare in the dry snow region in its center. In July 2012, however, satellites observed for the first time surface melt across more than 97 percent of the ice sheet, generating reports that the event was almost exclusively the result of climate change. In the new report, published in the journal Proceedings of the National Academy of Sciences
, researchers found that in both 2012 and 1889 exceptionally warm temperatures combined with black carbon sediments from Northern Hemisphere forest fires to darken the surface of the ice sheet to a critical albedo threshold, causing the large-scale melting events. Since Arctic temperatures and the frequency of forest fires are both expected to rise with climate change, large-scale melt events on the Greenland ice sheet may begin to occur almost annually by 2100, the researchers say.
Interview: Can Marine Life Adapt
To the World’s Acidifying Oceans?
As the world’s oceans grow more acidic from increased absorption of atmospheric carbon dioxide, marine scientists are confronting a key question: How well can
organisms like mollusks, crustaceans, and corals adapt to these more corrosive conditions? One of the leading authorities in this field is University of California, Santa Barbara marine biologist Gretchen Hofmann. Her work in recent years has shown, in fact, that some sea organisms that build shells do seem to have some ability to acclimate to more acidic waters. But in an interview with Yale Environment 360
, Hofmann cautions that this adaptive capacity has its limits. The continuing burning of fossil fuels, she says, could push ocean acidity past a tipping point, rendering some mollusks and other organisms unable to build shells.
Read the interview.
08 May 2014:
Natural Variations May Account
For Up to Half of Greenland's Warming
Up to half of the recent climate change in Greenland and surrounding regions — which have warmed at roughly twice the pace of the rest of the planet since 1979 — may be due to natural climate variations that originate in the tropical Pacific and are not connected
Meltwater from Russell Glacier
with the overall warming of the Earth, a new study
says. Still, at least half the warming remains attributable to rising global carbon dioxide emissions, according to research published in the journal Nature
. Climate data and advanced computer models show that changes in the western tropical Pacific Ocean, which has been about 0.3 degrees warmer than normal, have caused shifts in atmospheric pressure over the North Atlantic. Those changes set off a stationary wave in the atmosphere that arcs in a great circle from the tropical Pacific toward Greenland, pulling warmer air over that massive island. "Along this wave train there are warm spots where the air has been pushed down, and cold spots where the air has been pulled up," one author explained. "And Greenland is in one of the warm spots."
Carries on in Key Arctic Ecosystem
At a time of rapidly deteriorating relations between Russia and America, U.S. scientist Joel Berger continues his work with his Russian counterparts
Third in a series of blog posts from the Russian Arctic
on Siberia's Wrangel Island. In the third of three blog posts for Yale Environment 360
, Berger — a biologist with the Wildlife Conservation Society and the University of Montana — writes about efforts to better understand how rapid climate change might affect muskoxen and other wildlife in the Russian and North American Arctic. As Berger explains, a key focus of Russian-American scientific cooperation is Beringia, the region of northwestern Alaska and extreme northeastern Russia where two countries — and continents — are divided by the Bering Sea.
29 Apr 2014:
Exxon Mobil Arctic Project
Possibly At Risk Over Russia Sanctions
Exxon Mobil's development of a Russian Arctic oil project valued at nearly $900 billion is at risk following recent U.S. sanctions on Russian officials as a result of Ukraine's ongoing political crisis, Bloomberg News reports
. Exxon Mobil has partnered with the Russian state-controlled oil company OAO Rosneft to drill an oil-rich geological structure known as Universitetskaya, which contains an estimated 9 billion barrels of oil, valued at $900 billion at current market prices. Rosneft's CEO, Igor Sechin, a longtime member of Russian President Vladimir Putin's inner circle, was sanctioned by the U.S. yesterday, exposing the partnership with Exxon Mobil to additional scrutiny. Exxon Mobil and Rosneft are set to invest an estimated $600 million in drilling at the site in the Kara Sea, which would make the project Exxon's most expensive to-date. A U.S. Treasury official said yesterday that U.S. companies can still do business with Rosneft, but some analysts say Russian companies could become wary of working with Western corporations in the future. Exxon said last week that the project is on schedule.
Studying a Polar Menagerie
On an Island in Arctic Russia
Ninety miles from the Russian mainland and 300 miles above the Arctic Circle, Wrangel Island is home to an eclectic assortment of fauna and flora — muskoxen,
Second in a series of blog posts from the Russian Arctic
polar bears, wolves, reindeer, wolverines, walruses, Asia’s only population of snow geese, and 417 plant species. Joel Berger, a field biologist with the Wildlife Conservation Society and the University of Montana, spent several weeks on Wrangel Island this spring. In the second of three blog posts for e360
, he describes the arduous conditions under which Russian and U.S. scientists collect data on the island’s odd assortment of creatures.
On Far-Flung Wrangel Island,
A Scientist Sizes up Muskoxen
As a field biologist for the University of Montana and the Wildlife Conservation Society, Joel Berger has been to his share of end-of-the-earth places. But few have
Muskoxen on Wrangel Island
rivaled Wrangel Island, the rugged, frozen outpost located 300 miles above the Arctic Circle in Russia’s extreme Far East. In the first of three reports for Yale e360
, Berger describes the arduous trip to Wrangel and the scientific work that has taken him there — research with Russian colleagues on the island’s 900 muskoxen, a shaggy beast that is a relic from the Pleistocene era. In subsequent reports, Berger will describe the motley assortment of wildlife that has colonized Wrangel and the contrasting impacts of climate change on eastern Siberia and Arctic Alaska.