On September 16, the extent of the Arctic Ocean’s ice cap reached a new low, shrinking to 1.32 million square miles, 300,000 square miles less than the previous record low set in 2007. Some scientists believe that, at this rate, the Arctic could be ice-free by 2030 or even earlier. The Arctic may seem remote, but the overall rate of global warming, our climate and weather, sea levels, and many ecosystems and species will be affected by the warming that is occurring there.
The Arctic includes the Arctic Ocean and northern parts of Canada, Russia, Denmark (Greenland), Norway, the United States (Alaska), Sweden, Finland and Iceland. Arctic winters are cold and for a time, dark 24 hours a day. The ocean surface begins to freeze in mid-September and remains frozen until March, when it melts again through summer as the region gets sunlight 24 hours a day. The term “ice-free Arctic” refers to the Arctic Ocean in summer time.
During the last three decades, about 50 percent of Arctic sea ice cover, 80 percent of sea ice volume (thickness) and much of the old multiyear ice have been lost.
During the 1980s, half the winter ice remained for one or more seasons, but by 2012, only 25 percent of the ice that remained was more than a year old, with the rest thinner and more easily melted. Many climate models predicted that summer sea ice would remain through this century and into the next, so the speed at which sea ice loss is occurring has taken scientists by surprise.
In the last 40 years, the planet has warmed about 0.8˚ C, but the Arctic has been warming twice as fast due to the Gulf Stream’s warmer waters, 24-hour sunlight in summer, and more exposed ocean that absorbs the sun’s radiation. Since 1987, summer temperatures on the Svalbard Archipelago in Norway, 400 miles north of mainland Europe, have been 2˚ to 2.5˚ C higher than at any time in the last 1,800 years according to a new study led by William D’Andrea, a climate scientist at Lamont-Doherty Earth Observatory. Another recent study concluded that manmade greenhouse gas emissions are responsible for 70 to 95 percent of the Arctic melting since 1979.
As the sea ice melts, the Arctic’s reflective white cover is replaced by dark ocean water that absorbs more of the sun’s heat, warming the ocean and contributing to further melting. Even when ice remains, if it is thin, sunlight penetrates it and warms the water.
Melting sea ice doesn’t directly contribute to sea level rise (because the ice is floating and displaces its weight in water), but the expansion of warmer waters does. Moreover, the warmer water and air are hastening the melting of the 1.9-mile-thick ice sheet that sits atop most of Greenland, which also adds to sea level rise—summer melting on the ice sheet increased 30 percent between 1979 and 2006. During this past July, 97 percent of the ice sheet experienced some degree of melting, and as it melts, the exposed land absorbs more sunlight. If the ice sheet melts completely, global sea levels could rise 20 feet.
Some Lamont-Doherty Earth Observatory researchers are working with NASA on Operation ICE Bridge to measure and monitor the thickness of the Greenland ice sheet, and study what lies beneath the ice shelves (the ends of the ice sheet that extend over the ocean); how much water there is below can influence how fast the ice melts or how much breaks off. Other research by a Lamont seismologist has found a link between breakage of the ice sheet and glacial earthquakes, and documents the northward progression of these ice quakes towards one of the coldest parts of Greenland.
Much of the Arctic is covered by permafrost, soil at or below the freezing point of water for two or more years. Permafrost stores carbon from dead plants, and the cold prevents microbes from decomposing the organic matter. It is estimated that Arctic permafrost holds 1.7 trillion tons of carbon—more than all human activity has generated since the start of the Industrial Revolution. As warmer temperatures thaw the permafrost, the organic matter decays and releases carbon dioxide and methane, a heat-trapping gas 23 times more potent than carbon dioxide.
A Canadian study predicted that Canada’s thawing permafrost would release 75-560 billion tons of carbon into the atmosphere by 2100, raising the Earth’s temperature by 0.5˚C in addition to the 2 degrees C already expected due to global warming. The seabed beneath parts of the Arctic Ocean are thought to hold another 10 trillion tons of carbon locked in crystalline structures of water similar to ice called methane hydrates, but researchers believe this methane release is only a distant threat.
The Arctic, in its role as a global air conditioner, influences our weather. The difference in fall and winter temperatures between the colder Arctic and more southern regions is what propels the jet stream, which moves weather patterns around the Northern Hemisphere. But warmer Arctic temperatures have lessened that differential, affecting the jet stream’s west-to-east speed; as a result, weather conditions seem to stall in place for a longer time, creating extreme snowfalls, droughts and heat waves.
In addition, Arctic warming increases the swing of waves in the jet stream, allowing cold Arctic air to reach further south and warm air to penetrate further north, which also brings record-breaking temperatures. These changing weather patterns will likely have serious implications for global food production. For example, according to the Goddard Institute for Space Studies climate model, sea ice loss would make Kansas 2˚ C warmer in the winter, resulting in 40 percent less snow cover, which would impact its ability to grow winter wheat. It would also raise summer temperatures a few degrees and reduce Kansas’ soil moisture by 10 percent.
Large influxes of fresh water are entering the Arctic Ocean from the melting glaciers, sea ice (which is fresh because salt is pushed down when ice forms), and Greenland’s ice sheet. Lamont-Doherty scientists involved in the Arctic Switchyard Project are studying how much fresh water is entering the system, where it comes from, and how it affects ocean circulation and climate. Channels and currents in the Arctic Ocean behave like a switchyard, pushing fresh water into the North Atlantic where small changes could potentially have large impacts on climate elsewhere.
Some scientists are keeping an eye on the thermohaline circulation, an ocean “conveyor belt” that carries warm water from the equator north to the pole near the surface, while the depths carry cold dense polar water south towards the equator. This circulation maintains the temperature balance around the planet and keeps Europe relatively warm. The large amount of fresh water entering the Arctic Ocean could theoretically disrupt the thermohaline circulation, and bring cooling to the North Atlantic. Fresh water stays closer to the surface, and could interfere with the sinking of cold water at the pole that supports the thermohaline circulation. Scientists now consider a collapse of the thermohaline circulation (the basis of “The Day After Tomorrow,” a movie about New York freezing over) a more distant tipping point; however, the thermohaline circulation is expected to weaken this century.
According to the Arctic Biodversity Trends 2010 report, all types of habitats—sea ice, tundra, permafrost peatlands, ponds and lakes formed by melting permafrost—are changing and impacting biodiversity. There is less ice for species that depend on sea ice for hunting, breeding or sheltering their young, such as polar bears, walruses, and certain kinds of seals. As the permafrost thaws, the Arctic tundra is gradually becoming shrubbier. Shrubs trap snow in winter, which insulates soil and keeps it warmer, spurring the decomposition that returns more carbon into the atmosphere. The loss of grasses and mosses on the tundra may impact the caribou and reindeer populations. And the changing vegetation makes the tundra more vulnerable to wild fires. In addition, the earlier melting of ice, flowering and emergence of insects could cause mismatches between access to food and the timing of reproduction for many species whose life cycles are synchronized with the coming of spring and summer.
At “Warming Arctic, Changing Planet,” a forum held recently by the Earth Institute, Lamont-Doherty Earth Observatory and the Quebec Government, Lamont assistant research professor Natalie Boelman discussed her research on how tundra shrub growth and weather are affecting migratory songbirds. Hundreds of bird species migrate from around the world to breed in the Arctic. Extra snow on the shrubbier tundra may delay the uncovering of seeds, leaving the birds with little to eat after their long journeys.
“And what happens on the tundra doesn’t necessarily stay on the tundra,” said Boelman. “These migrating songbirds connect the tundra ecosystem with many other ecosystems all over the world, so anything that happens to these birds as a result of warming could, for example, impact who and how many may show up in your backyard bird feeder.” Songbirds provide critical ecosystem services such as insect control, seed dispersal and pollination, and serve as a food source for local predators.
Phytoplankton increased 20 percent between 1998 and 2009, and now blooms 50 days earlier than it did during that period. New data suggests that earlier estimates of phytoplankton bloom may be 10 times too low. These blooms directly impact marine species and will likely have implications up the food chain. Ice-free waters also absorb more CO2, which makes the ocean more acidic, reducing its carrying capacity for calcium carbonate that shellfish and corals need to build their shells and skeletons.
As Arctic waters warm and sea ice melts, species endemic to the North Atlantic Ocean are making their way north and whales once impeded by ice, such as killer whales, humpback, blue and gray whales, are coming into the region. Migratory invasive species are also on the increase, displacing some Arctic species. Scientists don’t yet know what the repercussions of all these changes will be.
The 9 million people who live in the Arctic must contend with coastal erosion, thawing permafrost, warmer temperatures, and changes in the animal and plant species that some traditional lifestyles depend upon. And yet, while sea rise and coastal erosion threaten these communities, the warming of the Arctic also provides new opportunities.
As the permafrost thaws, more areas might be able to support agriculture, and an earlier spring could boost plant growth and allow for a longer growing season. Arctic residents could benefit as more fish species like cod and herring move north because of warming oceans further south. The growth in phytoplankton might also support new fisheries, and less ice cover could provide access to different fish species.
In August 2007, the Northwest Passage, a sea route through the Arctic Ocean which connects the Atlantic and Pacific Oceans, opened up to ships for the first time since 1972 when record keeping began. The passage provides a trade route thousands of miles shorter than current trade routes through the Panama Canal. Icebreakers are also finding it easier to navigate through the thinner ice of the Northern Sea Route between East Asia and Europe, which is 40 percent shorter than crossing the Indian Ocean and going through Egypt’s Suez Canal. The shorter sea routes are a boon for commerce, saving time and fuel.
The U.S. Geological Survey projects that 22 percent of the world’s untapped oil, natural gas and natural gas liquid reserves lie in the Arctic, as well as abundant deposits of minerals, including rare earth metals essential for modern technology. Various countries are scrambling for position in anticipation of the newly accessible riches, as oil and gas licenses for exploration are being issued. Local communities will benefit from these new economic opportunities, as will oil companies. Though mining may bring economic opportunity, however, more oil and gas exploitation will also mean more fossil fuel burning, and greenhouse gas emissions.
The Arctic’s new accessibility will bring more trade, tourism and scientific research, but it will also mean more risk of pollution and invasive species, manmade disasters like oil spills and shipping accidents, and illegal activity. The challenge will be to find a balance between the threats to the Arctic that warming represents and the many opportunities it provides.
“We can learn a lot about what’s going to happen down here from looking at what’s happening up there,” said Boelman. “I think the Arctic is actually a tool for conveying climate change to everybody…this stuff is happening right now. It’s not happening slowly, it’s happening fast. Pay attention because it’s coming our way, too.”
To learn more, visit The National Snow and Ice Data Center, and see “Chasing Ice”, the powerful documentary film about photographer James Balog, who is bearing witness to climate change as it happens.
To read more about the Earth Institute and Lamont-Doherty Earth Observatory’s work in the Arctic, see: