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Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Degraded and Disheveled, Arctic Sea Ice Ties for Second-Lowest Extent on Record
The National Snow and Ice Data Center (NSIDC) announced on Thursday that the extent of sea ice in the Arctic Ocean has apparently hit its summer minimum. The value of 4.14 million square kilometers (1.60 million square miles) reached on September 10 comes in just behind the record-low extent of 2012 and in a statistical tie with 2007 for second place (see Figure 1). Although refreezing has begun, it’s possible that a late burst of melting could lead to an even lower value in the next few days. This year’s minimum came in below the 4.38 million sq km predicted in August by the median of 39 outlooks submitted by participants in the Sea Ice Prediction Network.
Figure 1. Each year’s minimum in Arctic sea ice extent from 1979, when satellite measurement began, through 2016 (assuming that the September 10 minimum holds). Units are millions of square kilometers. Image credit: Zack Labe, @Zlabe.
Plenty of ice loss without Old Sol’s help
This summer’s polar weather didn’t fit the classic template for major ice loss, which makes the near-record depletion all the more striking and concerning. In 2007, a record-smashing minimum was achieved through weeks of round-the-clock sunshine, together with the Arctic Dipole pattern--an atmospheric setup that creates winds that compact sea ice and shove it to lower latitudes through the Fram Strait between Greenland and Norway. This year got off to a phenomenal head start, as winter temperatures north of the Arctic Circle were far higher than anything on record. Then the weather turned largely cloudy during the crucial period from late June into August, staving off what might otherwise have been a minimum even lower than 2012’s. Still, as NSIDC noted, “the upper ocean was quite warm this summer and ocean-driven melting is important during late summer.” Several weeks of intense storminess in August may have helped to churn up warmer water across the western Arctic, fostering melt from below.
“A large portion of the anomalously low ice can be attributed to the unusual winter/spring,” said Zack Labe, a Ph.D. student analyzing sea ice at the University of California, Irvine. “If we’d had a classic Arctic Dipole pattern this summer, I have no doubt we would have quickly approached or surpassed 2012.”
Figure 2. Comparison of sea ice concentration on September 5 of the years 2012 through 2016 (upper left to lower center), as derived from AMSR2 satellite data (Japan Aerospace Exploration Agency). Lighter areas denote a higher concentration of sea ice. Sea ice extent refers to the amount of ocean with data cells that are at least 15 percent ice-covered. Image credit: JAXA, courtesy A-Team/Arctic Sea Ice Forum.
Figure 3. Large amounts of open water can be seen in ice extending to the vicinity of the North Pole in this view from NASA’s Terra satellite collected on September 8, 2016. Image credit: NASA Worldview, courtesy slow wing, Arctic Sea Ice Blog.
”Rubble” near the North Pole
Sea ice extent (the amount of ocean with at least 15% ice coverage) is just one way to gauge Arctic sea ice--albeit a useful and important one--and the minimum summer extent is only one data point in that record. Just as you need to know more than the number of named storms to assess the fury of an Atlantic hurricane season, it’s helpful to look at the Arctic sea ice in three dimensions and across the calendar to gauge its true health.
In that broader view, Arctic sea ice is in terrible shape. The amount of multiyear ice--especially sections that survive for five or more years, serving as a bulwark against year-to-year ice loss--has dropped precipitously in the last 10 years. Huge swaths of ice that “survived” the summer of 2016 in terms of extent were actually riddled with gaping cracks and gaps. Figure 2 above shows the pockmarked state of this year’s early-September ice as compared with the previous four years. The eastern Arctic (top part of images) was especially ravaged, as shown more closely in Figure 3 above. Ice described by some observers as “rubble” extended to the vicinity of the North Pole, and a large expanse of open water could be seen behind the Swedish icebreaker Oden as it was moored to an ice floe within two miles of the North Pole on August 28. Areas of open water do occur at times near the North Pole, but the vast expanse of compromised high-latitude ice this year is stunning.
Figure 4. The yacht Northabout cuts through ice-studded waters. This year the Northabout is completing a circumnavigation of the Arctic Ocean as a way to increase attention to the effects of climate change on the region. Image credit: Polar Ocean Challenge.
A disturbingly successful trip around the Arctic
Both the Northeast and Northwest Passages opened up yet again this summer, a dual milestone that was first recorded in 2008. As part of a project called Polar Ocean Challenge, a 50-foot yacht called Northabout has become the first ship known to sail through both passages in a single summer. The yacht is now heading around the south side of Greenland en route to its home base in England. It took the Northabout a mere 14 days to complete the Northwest Passage, where the crew encountered ice only two times. “Whilst we are all delighted to have succeeded, it is extremely worrying to see this lack of ice so starkly,” said expedition leader David Templeman-Adams.
At the Arctic Sea Ice Blog, Neven Acropolis reflected on this odd summer: “I always thought that it would take extreme weather conditions as seen in 2007 for a melting season to end really low: Lots of open skies, warm winds and continuous compaction, just weeks and weeks of the same kind of weather. But given that there's no let-up in the amount of heat flowing into the Arctic--via air and especially ocean--other set-ups can be just as destructive. It will probably be a back-and-forth of high pressure (open skies) and low pressure (dispersal, mixing) that will lead to new records, and eventually an ice-free Arctic…Whatever it is we’re doing to stop this from getting worse in decades to come, we need to do it faster.”
For an update on tropical happenings in the Atlantic and Pacific, see my post from this morning with Jeff Masters. We’ll be back with our next update by Saturday afternoon.
Bob Henson
Figure 1. Each year’s minimum in Arctic sea ice extent from 1979, when satellite measurement began, through 2016 (assuming that the September 10 minimum holds). Units are millions of square kilometers. Image credit: Zack Labe, @Zlabe.
Plenty of ice loss without Old Sol’s help
This summer’s polar weather didn’t fit the classic template for major ice loss, which makes the near-record depletion all the more striking and concerning. In 2007, a record-smashing minimum was achieved through weeks of round-the-clock sunshine, together with the Arctic Dipole pattern--an atmospheric setup that creates winds that compact sea ice and shove it to lower latitudes through the Fram Strait between Greenland and Norway. This year got off to a phenomenal head start, as winter temperatures north of the Arctic Circle were far higher than anything on record. Then the weather turned largely cloudy during the crucial period from late June into August, staving off what might otherwise have been a minimum even lower than 2012’s. Still, as NSIDC noted, “the upper ocean was quite warm this summer and ocean-driven melting is important during late summer.” Several weeks of intense storminess in August may have helped to churn up warmer water across the western Arctic, fostering melt from below.
“A large portion of the anomalously low ice can be attributed to the unusual winter/spring,” said Zack Labe, a Ph.D. student analyzing sea ice at the University of California, Irvine. “If we’d had a classic Arctic Dipole pattern this summer, I have no doubt we would have quickly approached or surpassed 2012.”
Figure 2. Comparison of sea ice concentration on September 5 of the years 2012 through 2016 (upper left to lower center), as derived from AMSR2 satellite data (Japan Aerospace Exploration Agency). Lighter areas denote a higher concentration of sea ice. Sea ice extent refers to the amount of ocean with data cells that are at least 15 percent ice-covered. Image credit: JAXA, courtesy A-Team/Arctic Sea Ice Forum.
Figure 3. Large amounts of open water can be seen in ice extending to the vicinity of the North Pole in this view from NASA’s Terra satellite collected on September 8, 2016. Image credit: NASA Worldview, courtesy slow wing, Arctic Sea Ice Blog.
”Rubble” near the North Pole
Sea ice extent (the amount of ocean with at least 15% ice coverage) is just one way to gauge Arctic sea ice--albeit a useful and important one--and the minimum summer extent is only one data point in that record. Just as you need to know more than the number of named storms to assess the fury of an Atlantic hurricane season, it’s helpful to look at the Arctic sea ice in three dimensions and across the calendar to gauge its true health.
In that broader view, Arctic sea ice is in terrible shape. The amount of multiyear ice--especially sections that survive for five or more years, serving as a bulwark against year-to-year ice loss--has dropped precipitously in the last 10 years. Huge swaths of ice that “survived” the summer of 2016 in terms of extent were actually riddled with gaping cracks and gaps. Figure 2 above shows the pockmarked state of this year’s early-September ice as compared with the previous four years. The eastern Arctic (top part of images) was especially ravaged, as shown more closely in Figure 3 above. Ice described by some observers as “rubble” extended to the vicinity of the North Pole, and a large expanse of open water could be seen behind the Swedish icebreaker Oden as it was moored to an ice floe within two miles of the North Pole on August 28. Areas of open water do occur at times near the North Pole, but the vast expanse of compromised high-latitude ice this year is stunning.
Figure 4. The yacht Northabout cuts through ice-studded waters. This year the Northabout is completing a circumnavigation of the Arctic Ocean as a way to increase attention to the effects of climate change on the region. Image credit: Polar Ocean Challenge.
A disturbingly successful trip around the Arctic
Both the Northeast and Northwest Passages opened up yet again this summer, a dual milestone that was first recorded in 2008. As part of a project called Polar Ocean Challenge, a 50-foot yacht called Northabout has become the first ship known to sail through both passages in a single summer. The yacht is now heading around the south side of Greenland en route to its home base in England. It took the Northabout a mere 14 days to complete the Northwest Passage, where the crew encountered ice only two times. “Whilst we are all delighted to have succeeded, it is extremely worrying to see this lack of ice so starkly,” said expedition leader David Templeman-Adams.
At the Arctic Sea Ice Blog, Neven Acropolis reflected on this odd summer: “I always thought that it would take extreme weather conditions as seen in 2007 for a melting season to end really low: Lots of open skies, warm winds and continuous compaction, just weeks and weeks of the same kind of weather. But given that there's no let-up in the amount of heat flowing into the Arctic--via air and especially ocean--other set-ups can be just as destructive. It will probably be a back-and-forth of high pressure (open skies) and low pressure (dispersal, mixing) that will lead to new records, and eventually an ice-free Arctic…Whatever it is we’re doing to stop this from getting worse in decades to come, we need to do it faster.”
For an update on tropical happenings in the Atlantic and Pacific, see my post from this morning with Jeff Masters. We’ll be back with our next update by Saturday afternoon.
Bob Henson
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.