By Paul Beckwith
From my chair, it looks to me like there will be zero sea ice in the Arctic by September 30th of this year 2012.
The massive cyclone in the Arctic of unprecedented size has been chewing up the sea ice for the last week and it looks like over 1 million square km has been lost. A few more cyclones there will finish it off completely.
My presentation on the link below needs polishing, is quite technical in places and is mostly my compilation of blogs and data and comments from other scientists, engineers, and lay-people. It is mostly in chronological order as the storm has progressed.
Sea ice in the Arctic - Shaken and stirred (by a powerful cyclone)
August 3 to 10, 2012, by Paul Beckwith
https://docs.google.com/open?id=0B7jFQnAaMpkXVFNLRUhXUmdaWk0
Friday, August 10, 2012
Thursday, August 2, 2012
Year 2012 set to break all records
The image below, edited from the National Snow & Ice Data Center, shows that Arctic sea ice extent is at a record low for the time of the year.
According to measurements by the Institut für Umweltphysik at the University of Bremen a new historic Arctic sea ice minimum was reached on 8 September, 2011. The year 2012 looks set to reach even lower extent.
The nosedive taken by the sea ice over the past few months also shows up in measurements of the sea ice area.
The image below shows a retreat in sea ice area to 3.91533 million km2 on the 212th day of 2012, also a record low for this time of year. The Cryosphere Today features the original interactive image.
Most critical is ice volume. The animation below, from NASA/Goddard Visualization Studio images, shows how much Arctic multi-year sea ice has declined over the years.
The Polar Science Center reports ice volume for July 2012 of 8300 km3, i.e. about 700 km3 less than July 2011, 65% lower than the maximum in 1979, and 55% below the mean, as illustrated by the image below.
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| Click here for large version of PIOMAS Daily Arctic Sea Ice Volume |
As the image on the left shows, the annual minimum for Arctic sea ice volume is getting perilously close to zero, raising the risk of a collapse of the sea ice in the Arctic.Temperature rises and larger areas of open water increase the likelihood of storms, as well as their intensity. Sea ice is now getting so thin that it becomes prone to break up in case of strong waves.
Heavy winds from the Bering Strait could then drive most sea ice across the Arctic Ocean, to pile up against Greenland, where it could persist for somewhat longer.
The subsequent dramatic increase in area of open water would cause a huge albedo change, making that much more sunlight in the Arctic would be absorbed, instead of reflected back into space as was previously the case.
This, together with additional feedbacks, could dramatically increase temperatures in the Arctic, further accelerating warming in the Arctic.
Water from rivers flowing into the Arctic could be heated up significantly during heatwaves. On the NOAA image below, the 20 degrees Celsius isobar appears to touch the coastline of the Laptev Sea, with the 25 degrees isobar not far behind. Just below the 20 degrees mark on the map, there's a spot with one-day mean temperatures of over 30 degrees Celsius.
The image below, edited from the Naval Research Laboratory of the U.S. Navy, shows areas with surface temperatures of 8 degrees Celsius and higher in many areas on the edges of the Arctic Ocean from where sea ice has already retreated.
These are huge anomalies, as illustrated by the image below, from the Danish Meteorological Institute.
The danger is that high temperatures will trigger methane releases from hydrates and free gas in sediments, as discussed in this post on the potential impact of large abrupt release of methane in the Arctic and this post describing that Greenland is melting at incredible rate. For more on this danger and, importantly, what to do about it, see the presentation Why act now, and how?
Tuesday, July 24, 2012
Greenland is melting at incredible rate
The combination-image below shows how much the ice on Greenland melted between July 8 (left) and July 12 (right).
On average in the summer, about half of the surface of Greenland's ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97% of the ice sheet surface thawed at some point in mid-July.
This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland's weather since the end of May. "Each successive ridge has been stronger than the previous one," said Mote. This latest heat dome started to move over Greenland on July 8, and then parked itself over the ice sheet about three days later. By July 16, it had begun to dissipate.
As the ice warms, it loses albedo, i.e. less sunlight is reflected back into space. Darker surface absorbs more sunlight, accelerating the melting. The image below shows the Greenland ice sheet albedo from 2000 to 2011.
The photo below shows how dark the ice sheet surface can become.
The July data since 2000, from the meltfactor blog, suggest a exponential fall in reflectivity that, when projected into the future (red line, added by Sam Carana), looks set to go into freefall next year.
Is a similar thing happening all over the Arctic? Well, the map below, edited from a recent SSMIS Sea Ice Map, shows that sea ice concentration is highest around the North Pole.
So, can water be expected to show up at the North Pole? Well have a look at the photo from the North Pole webcam below.
It does look like melting is going on at the North Pole. Water is significantly darker than ice, meaning the overall reflectivity will be substantially lowered by this water.
It's important to realize that surface albedo change is just one out of a number of feedbacks, each of which deserves a closer look.
As shown on the image below, the IPCC describes four types of feedbacks with a joint Radiative Forcing of about 2 W/sq m, i.e. water vapor, cloud, surface albedo and lapse rate.
The image below, from James Hansen et al., may at first glance give the impression that all aerosols have a cooling effect.
When components are split out further, it becomes clear though that some aerosols are reflective and have a cooling effect, whereas black carbon has a warming effect, while changes in snow albedo also contribute to warming. On the interactive graph below, you can click on or hover over each component to view their radiative forcing.
When isolated from other factors, it's clear that snow albedo has an increasing warming effect.
How much could Earth warm up due to decline of snow and ice? Professor Peter Wadhams estimates that the drop in albedo in case of total loss of Arctic sea ice would be a 1.3 W/sq m rise in radiative forcing globally, while additional decline of ice and snow on land could push the the combined impact well over 2 W/sq m.
Locally, the impact could be even more dramatic. The image below, from Flanner et al., shows how much the snow and ice is cooling the Arctic.
Conversely, above image shows how much the Arctic could warm up without the snow and ice. Due to albedo change, sunlight that was previously reflected back into space will instead warm up the Arctic. What could have a big impact locally is that, where there's no more sea ice left, all the heat that previously went into melting will raise temperatures instead, as described at Warming in the Arctic.
The big danger is methane. Drew Shindell et al. show in Improved Attribution of Climate Forcing to Emissions that inclusion of aerosol responses will give methane a much higher global warming potential (GWP) than the IPCC gave methane in AR4, adding that methane's GWP would likely be further increased by including ecosystem responses. Indeed, as pictured in the image below, accelerated warming in the Arctic could trigger methane releases which could cause further methane releases, escalating into runaway global warming.
On July 8, about 40% of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and some 97% of the ice sheet surface had thawed by July 12.
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| In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting. The satellites are measuring different physical properties at different scales and are passing over Greenland at different times. Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory. |
For several days this month, Greenland's surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.
On average in the summer, about half of the surface of Greenland's ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97% of the ice sheet surface thawed at some point in mid-July.
This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland's weather since the end of May. "Each successive ridge has been stronger than the previous one," said Mote. This latest heat dome started to move over Greenland on July 8, and then parked itself over the ice sheet about three days later. By July 16, it had begun to dissipate.
As the ice warms, it loses albedo, i.e. less sunlight is reflected back into space. Darker surface absorbs more sunlight, accelerating the melting. The image below shows the Greenland ice sheet albedo from 2000 to 2011.
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| Credit: NOAA Arctic Report Card 2011. |
The image below, from the meltfactor blog and by Jason Box and David Decker, shows the steep fall in reflectivity for altitudes up to 3200 meters in July 2012.
The image below, from the meltfactor blog, shows how the year 2012 compares with the situation at approximately the same time in previous years, 2011 and 2010, which are recognized as being record melt years.
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| Photo shot by Jason Box on August 12, 2005 |
Loss of albedo occurs as the darker bare ground becomes visible where the ice has melted away. Darkening of snow and ice can start even before melting takes place. Warming changes the shape and size of the ice crystals in the snowpack, as described at this NASA Earth Observatory page. As temperatures rise, snow grains clump together and reflect less light than the many-faceted, smaller crystals. Additional heat rounds the sharp edges of the crystals, and round particles absorb more sunlight than jagged ones.
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| Dirty ice surrounds a meltwater stream near the margin of the ice sheet. Compared to fresh snow and clean ice, the dark surface absorbs more sunlight, accelerating melting. © Henrik Egede Lassen/Alpha Film, from the Snow, Water, Ice, and Permafrost in the Arctic report from the U.N. Arctic Monitoring and Assessment Programme. From NOAA Climatewatch. |
Another factor contributing to darkening is aerosols, in particular soot (i.e. black carbon) from fires and combustion of fuel, dust and organic compounds that enter the atmosphere and that can travel over long distances and settle on ice and snow in the Arctic.
The July data since 2000, from the meltfactor blog, suggest a exponential fall in reflectivity that, when projected into the future (red line, added by Sam Carana), looks set to go into freefall next year.
Is a similar thing happening all over the Arctic? Well, the map below, edited from a recent SSMIS Sea Ice Map, shows that sea ice concentration is highest around the North Pole.
So, can water be expected to show up at the North Pole? Well have a look at the photo from the North Pole webcam below.
 |
| Photo from the North Pole webcam |
It's important to realize that surface albedo change is just one out of a number of feedbacks, each of which deserves a closer look.
As shown on the image below, the IPCC describes four types of feedbacks with a joint Radiative Forcing of about 2 W/sq m, i.e. water vapor, cloud, surface albedo and lapse rate.
The image below, from James Hansen et al., may at first glance give the impression that all aerosols have a cooling effect.
How much could Earth warm up due to decline of snow and ice? Professor Peter Wadhams estimates that the drop in albedo in case of total loss of Arctic sea ice would be a 1.3 W/sq m rise in radiative forcing globally, while additional decline of ice and snow on land could push the the combined impact well over 2 W/sq m.
Locally, the impact could be even more dramatic. The image below, from Flanner et al., shows how much the snow and ice is cooling the Arctic.
 |
| Image, edited by Sam Carana, from Mark Flanner et al. (2011). |
The big danger is methane. Drew Shindell et al. show in Improved Attribution of Climate Forcing to Emissions that inclusion of aerosol responses will give methane a much higher global warming potential (GWP) than the IPCC gave methane in AR4, adding that methane's GWP would likely be further increased by including ecosystem responses. Indeed, as pictured in the image below, accelerated warming in the Arctic could trigger methane releases which could cause further methane releases, escalating into runaway global warming.
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