Arctic Ice Record Low - Arctic sea ice just hit a record low. Here’s why it matters. The Arctic Ocean’s vast frozen expanse of ice is rapidly vanishing. On Monday, scientists at the National Snow and Ice Data Center announced that the extent of sea ice in the Arctic had reached its lowest level since satellite measurements began, breaking the previous record in 2007. That’s particularly striking because the summer melting season still has about two more weeks to go.
It’s clear that Arctic sea ice is now shriveling more quickly each year. And scientists say the melt is driven by both global warming and other pollutants that humans have put into the atmosphere. But why does the disappearing sea ice actually matter? For one, it’s a sign of how quickly we’re heating the planet. But the vanishing sea ice can also have side effects of its own — from warming up the Arctic further to unlocking once-frozen areas of the north for oil and gas exploration. Below is a rundown of what we know about Arctic sea ice and why it’s worth watching.
1) The amount of Arctic sea ice is shrinking each year — and will soon disappear altogether in the summer months if the planet keeps warming. Since the 1980s, agencies around the world have used satellites to measure the extent of Arctic sea ice. This chart from the Japan Aerospace Exploration Agency (JAXA) shows the clear trend over time:
Over the past three decades, the extent of Arctic sea ice that remains after the summer melt has declined 40 percent. Mark Serreze, director of the National Snow and Ice Data Center, told the Guardian last year: “The extent is going down, but it is also thinning…. There will be ups and downs, but we are on track to see an ice-free summer by 2030.”
2) Humans are largely to blame for the Arctic melt. A new study in this month’s Environmental Research Letters concludes that between 70 and 95 percent of the Arctic melt since 1979 has been caused by human activity. Human-caused global warming has rapidly heated up the Arctic — the region has been warming about twice as fast as the global average. (See here for a good explanation of why.) What’s more, winds have carried soot and other dark particles from factories in Europe and Asia into the Arctic. When those particles settle onto the snow and ice, they absorb sunlight and start sizzling.
Natural variability still plays a small role, however. This year, a large storm in August may have helped break up the sea ice and caused it to melt even more quickly. But NSIDC scientists say the long-term warming trend was the main driver — the increasingly slushy ice is even more vulnerable to severe weather.
3) Scientists have often underestimated the speed with which Arctic sea ice is vanishing. In 2007, the Intergovernmental Panel on Climate Change (IPCC) figured we wouldn’t see ice-free summers in the Arctic until the end of the century or so. But later observations suggested that sea-ice extent is shrinking far more quickly than the IPCC had predicted.
It appears that earlier climate models underestimated certain “feedback” effects. As Arctic ice melts, more and more of the ocean is exposed to sunlight. Since the darker ocean surface absorbs more sunlight than the bright ice, that warms the region even further. What’s more, a recent study in the Journal of Geophysical Letters found that IPCC models had low-balled the pace at which melted ice drifts away, further accelerating the collapse. That explains why scientists now believe we could see ice-free summers some 50 years ahead of the IPCC’s schedule.
4) Melting Arctic sea ice won’t, by itself, raise global ocean levels. But a warmer Arctic will cause Greenland’s ice sheet to melt — and that matters. Ice that’s already bobbing in the ocean can’t raise sea levels because the ice was already displacing its own volume. But as more of the Arctic Ocean is exposed to sunlight, the region will keep heating up. And that’s particularly worrisome when it comes to the vast ice sheet covering Greenland.
Greenland’s ice sheet is 1.9 miles thick and contains enough ice to raise global sea levels by about 25 feet (7.5 meters) all told. Back in 2007, the IPCC consensus was that Greenland’s ice sheet would remain fairly stable this century and wouldn’t contribute much to sea level rise. But more recent evidence suggests this is also way too optimistic. The melting of Greenland’s ice sheet appears to be accelerating of late, losing about four times as much mass last year as it did a decade ago. That’s partly due to warmer air. And it’s partly driven by rising ocean temperatures, as water chews away at the edge of the sheet.
As a result, a recent study by the U.S. Jet Propulsion Laboratory predicted, sea levels could now rise at least a foot by mid-century, possibly three feet by century’s end. (A lot also depends on how rapidly Antarctica’s ice sheets melt.)
5) The changing Arctic could lead to more extreme summers and winters in the United States and Europe. It’s no shock that global warming will make summers even hotter. But could it also make winters colder? Perhaps. For that, we can thank the Arctic. As Jennifer Francis, a climate scientist at Rutgers, has started exploring, the amplified warming in the Arctic could help drive extreme weather patterns.
Why is that? First, the west-to-east jet stream appears to be slowing down, which allows weather patterns to persist in certain areas for longer. This might account for the onslaught of snowstorms in the United States and Europe in 2009 and 2010, as well as prolonged heat waves like the one that hit Moscow in 2010. Arctic amplification could also increase the “waviness” of the jet stream surrounding the polar regions. That could occasionally send blasts of cold Arctic air down into North America or Europe, causing frigid winters.
6) Other doomsday scenarios — a shutdown in ocean circulation, or vast methane releases from permafrost — don’t appear imminent, though they’re worth watching. Scientists are keeping a wary eye on two Arctic developments. First, there’s the possibility that a flood of cold water from melting glaciers and icebergs could eventually disrupt the “overturning circulation” in the Atlantic Ocean that keeps temperatures in Europe mild. There’s evidence this has happened several times in the past 60,000 years. Yet no climate model has suggested that a shutdown could happen this century. Europe appears safe for now.
More worrisome is the chance that vast permafrost in Siberia and elsewhere will keep melting, unlocking vast quantities of methane, which would, in turn, further heat the planet. A survey of 41 scientists published in Nature last year estimated that, at current melt rates, methane from terrestrial permafrost could eventually contribute 2.5 times as much to climate change as deforestation now does. And yet, as ocean chemist David Archer notes here, a catastrophic “methane bomb” erupting from either permafrost or icy ocean clathrates appears unlikely anytime soon. A small consolation, perhaps.
7) A warmer Arctic will allow oil and gas companies to produce even more fossil fuels. The melting Arctic sea ice makes it easier for oil and gas companies to explore northern offshore regions that were once inaccessible. As my colleague Juliet Eilperin just reported, Shell is sending a drill ship to the Chukchi Sea off Alaska as it prepares for oil exploration in the region. Last year, ExxonMobil signed a $500 million deal with Rosneft to develop offshore reserves in Russia’s once-frozen Kara sea. This is a little-discussed Arctic “feedback” mechanism — less ice means more oil and gas which, when burned, will heat the planet further. Repeat until ice-free.
8) The Arctic hasn’t reached the “point of no return,” but the world would have to cut emissions very quickly to stabilize the sea ice. One 2010 study in Nature found that it was still technically possible to stabilize the collapse of Arctic sea ice. A more recent study in Science, looking at 10,000 years of Arctic melt, also concluded that we’re not yet at a “tipping point,” where the collapse in sea ice becomes inevitable. “The good news,” said author Sven Funder, “is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return.”
And yet, as climate blogger Joe Romm explained after the Nature study came out, we may have reached a practical point of no return. The Nature authors estimated that the world might have to cut greenhouse-gas emissions by 60 percent immediately and keep cutting thereafter to avert the inexorable collapse of summer sea-ice. That’s unlikely. A (shrinking) number of climate scientists still think the world can cut emissions significantly and avert a 2°C rise in temperature. Yet the prognosis for Arctic sea ice looks a bit grimmer.
It’s clear that Arctic sea ice is now shriveling more quickly each year. And scientists say the melt is driven by both global warming and other pollutants that humans have put into the atmosphere. But why does the disappearing sea ice actually matter? For one, it’s a sign of how quickly we’re heating the planet. But the vanishing sea ice can also have side effects of its own — from warming up the Arctic further to unlocking once-frozen areas of the north for oil and gas exploration. Below is a rundown of what we know about Arctic sea ice and why it’s worth watching.
1) The amount of Arctic sea ice is shrinking each year — and will soon disappear altogether in the summer months if the planet keeps warming. Since the 1980s, agencies around the world have used satellites to measure the extent of Arctic sea ice. This chart from the Japan Aerospace Exploration Agency (JAXA) shows the clear trend over time:
(Source: JAXA)
2) Humans are largely to blame for the Arctic melt. A new study in this month’s Environmental Research Letters concludes that between 70 and 95 percent of the Arctic melt since 1979 has been caused by human activity. Human-caused global warming has rapidly heated up the Arctic — the region has been warming about twice as fast as the global average. (See here for a good explanation of why.) What’s more, winds have carried soot and other dark particles from factories in Europe and Asia into the Arctic. When those particles settle onto the snow and ice, they absorb sunlight and start sizzling.
Natural variability still plays a small role, however. This year, a large storm in August may have helped break up the sea ice and caused it to melt even more quickly. But NSIDC scientists say the long-term warming trend was the main driver — the increasingly slushy ice is even more vulnerable to severe weather.
3) Scientists have often underestimated the speed with which Arctic sea ice is vanishing. In 2007, the Intergovernmental Panel on Climate Change (IPCC) figured we wouldn’t see ice-free summers in the Arctic until the end of the century or so. But later observations suggested that sea-ice extent is shrinking far more quickly than the IPCC had predicted.
It appears that earlier climate models underestimated certain “feedback” effects. As Arctic ice melts, more and more of the ocean is exposed to sunlight. Since the darker ocean surface absorbs more sunlight than the bright ice, that warms the region even further. What’s more, a recent study in the Journal of Geophysical Letters found that IPCC models had low-balled the pace at which melted ice drifts away, further accelerating the collapse. That explains why scientists now believe we could see ice-free summers some 50 years ahead of the IPCC’s schedule.
4) Melting Arctic sea ice won’t, by itself, raise global ocean levels. But a warmer Arctic will cause Greenland’s ice sheet to melt — and that matters. Ice that’s already bobbing in the ocean can’t raise sea levels because the ice was already displacing its own volume. But as more of the Arctic Ocean is exposed to sunlight, the region will keep heating up. And that’s particularly worrisome when it comes to the vast ice sheet covering Greenland.
Greenland’s ice sheet is 1.9 miles thick and contains enough ice to raise global sea levels by about 25 feet (7.5 meters) all told. Back in 2007, the IPCC consensus was that Greenland’s ice sheet would remain fairly stable this century and wouldn’t contribute much to sea level rise. But more recent evidence suggests this is also way too optimistic. The melting of Greenland’s ice sheet appears to be accelerating of late, losing about four times as much mass last year as it did a decade ago. That’s partly due to warmer air. And it’s partly driven by rising ocean temperatures, as water chews away at the edge of the sheet.
As a result, a recent study by the U.S. Jet Propulsion Laboratory predicted, sea levels could now rise at least a foot by mid-century, possibly three feet by century’s end. (A lot also depends on how rapidly Antarctica’s ice sheets melt.)
5) The changing Arctic could lead to more extreme summers and winters in the United States and Europe. It’s no shock that global warming will make summers even hotter. But could it also make winters colder? Perhaps. For that, we can thank the Arctic. As Jennifer Francis, a climate scientist at Rutgers, has started exploring, the amplified warming in the Arctic could help drive extreme weather patterns.
Why is that? First, the west-to-east jet stream appears to be slowing down, which allows weather patterns to persist in certain areas for longer. This might account for the onslaught of snowstorms in the United States and Europe in 2009 and 2010, as well as prolonged heat waves like the one that hit Moscow in 2010. Arctic amplification could also increase the “waviness” of the jet stream surrounding the polar regions. That could occasionally send blasts of cold Arctic air down into North America or Europe, causing frigid winters.
6) Other doomsday scenarios — a shutdown in ocean circulation, or vast methane releases from permafrost — don’t appear imminent, though they’re worth watching. Scientists are keeping a wary eye on two Arctic developments. First, there’s the possibility that a flood of cold water from melting glaciers and icebergs could eventually disrupt the “overturning circulation” in the Atlantic Ocean that keeps temperatures in Europe mild. There’s evidence this has happened several times in the past 60,000 years. Yet no climate model has suggested that a shutdown could happen this century. Europe appears safe for now.
More worrisome is the chance that vast permafrost in Siberia and elsewhere will keep melting, unlocking vast quantities of methane, which would, in turn, further heat the planet. A survey of 41 scientists published in Nature last year estimated that, at current melt rates, methane from terrestrial permafrost could eventually contribute 2.5 times as much to climate change as deforestation now does. And yet, as ocean chemist David Archer notes here, a catastrophic “methane bomb” erupting from either permafrost or icy ocean clathrates appears unlikely anytime soon. A small consolation, perhaps.
7) A warmer Arctic will allow oil and gas companies to produce even more fossil fuels. The melting Arctic sea ice makes it easier for oil and gas companies to explore northern offshore regions that were once inaccessible. As my colleague Juliet Eilperin just reported, Shell is sending a drill ship to the Chukchi Sea off Alaska as it prepares for oil exploration in the region. Last year, ExxonMobil signed a $500 million deal with Rosneft to develop offshore reserves in Russia’s once-frozen Kara sea. This is a little-discussed Arctic “feedback” mechanism — less ice means more oil and gas which, when burned, will heat the planet further. Repeat until ice-free.
8) The Arctic hasn’t reached the “point of no return,” but the world would have to cut emissions very quickly to stabilize the sea ice. One 2010 study in Nature found that it was still technically possible to stabilize the collapse of Arctic sea ice. A more recent study in Science, looking at 10,000 years of Arctic melt, also concluded that we’re not yet at a “tipping point,” where the collapse in sea ice becomes inevitable. “The good news,” said author Sven Funder, “is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return.”
And yet, as climate blogger Joe Romm explained after the Nature study came out, we may have reached a practical point of no return. The Nature authors estimated that the world might have to cut greenhouse-gas emissions by 60 percent immediately and keep cutting thereafter to avert the inexorable collapse of summer sea-ice. That’s unlikely. A (shrinking) number of climate scientists still think the world can cut emissions significantly and avert a 2°C rise in temperature. Yet the prognosis for Arctic sea ice looks a bit grimmer.
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