Tipping Points

The increasing melt may be a harbinger of greater changes such as the release of methane compounds from frozen soils that could exacerbate warming, and a thaw of the Greenland ice sheet, which would contribute to rising sea levels, NASA’s top climate scientist, James Hansen, said in an e-mail interview, reports Bloomberg.

“Our greatest concern is that loss of Arctic sea ice creates a grave threat of passing two other tipping points -- the potential instability of the Greenland ice sheet and methane hydrates,” Hansen said. “These latter two tipping points would have consequences that are practically irreversible on time scales of relevance to humanity.”

Above image shows methane levels over a period of four years, from August 1, 2008, to August 1, 2012.

Above image shows methane levels over one years, from August 1, 2011, to August 1, 2012. This shows a marked increase in methane levels on the last of the four years further above.

Above image shows methane levels from August 1, 2012, to August 15, 2012. The image shows high levels of methane across the northern hemisphere. Note the high levels above Greenland.

Arctic sea ice updates

Above diagram shows sea ice extent as calculated by the Polar View team at the University of Bremen, Germany.

Paul Beckwith warns that a second cyclone is threatening to batter the remaining sea ice soon.

View Paul's presentation by clicking on the link below.
https://docs.google.com/file/d/0ByLujhsHsxP7cnB0bXhNNFFSQjQ/edit


Or, view the presentation in the window below (it may take some time for the file to fully load).

Opening the Doorways to Doom

Snow and ice protect the Arctic from overheating in summer. Firstly the brightness of the snow and ice cover ensures that most sunlight gets reflected back into space. Secondly, a lot of the sunlight that isn't reflected will be consumed by the process of turning snow and ice into water, which occurs while temperatures remain at the melting point of 0°C (32°F, 273.15 K). 

The Arctic is further protected from overheating by the polar jet stream, which keeps cold air in the Arctic and keeps warm air out. 

The polar jet stream can travel at speeds greater than 100 mph. Here, the fastest winds are colored red; slower winds are blue. View animated version here. Credit: NASA/Goddard Space Flight Center

Accelerated warming in the Arctic can alter the polar jet stream in a number of ways, firstly by slowing its speed and secondly by increasing its waviness. Larger swings in the jet stream allow frigid air from the Arctic to plunge farther south, as well as warm, moist tropical air to penetrate northward, explains Jennifer Francis, research professor at the Institute of Marine and Coastal Sciences at Rutgers University. 

Accelerated warming in the Arctic comes with many feedbacks, and this "open doors feedback" is only one of them. Higher temperatures and more open water in the Arctic can also be expected to increase the danger that storms will batter the sea ice with greater ferocity. 

In many ways, it's opening the doorways to doom. The biggest danger is that Arctic methane stores will weaken, causing huge amounts of methane to be released, triggering warming that could escalate into runaway global warming.  

CryoSat

The image below shows how much the older, thicker sea ice has declined over the years. This decline doesn't become apparent when focusing on sea ice extent; volume measurements are needed to reveal this decline.

Old versus new ice in Arctic: The maps show the median age of sea ice in March 1985 (left) and March 2011 (right).
Overall, the proportion of old ice has decreased. By March 2011, ice over 4 years old accounts for less than
10% of the Arctic ice cover. Credit: National Snow and Ice Data Center, University of Colorado, Boulder.

The screenshot below shows GHRSST volume measurements from National Centre for Ocean Forecasting website.

The European Space Agency's CryoSat promises to deliver an even clearer picture. One of the scientists analyzing the CryoSat data, Dr Seymour Laxon, said in April 2012 that CryoSat's volume estimate is very similar to that of PIOMAS, the model developed at the Polar Science Center at the University of Washington.

In a recent interview, Dr Laxon said that if the current trend continues, the Arctic could be ice-free at the height of summer by the end of the decade.

John Nissen, Chair of the Arctic Methane Emergency Group (AMEG), comments: "Dr Laxon failed to mention the data on sea ice thickness that has been collected over many years by sea ice expert Professor Peter Wadhams of the University of Cambridge, who now considers that the Arctic Ocean will be seasonally free of sea ice most probably by September 2016. PIOMAS sea ice volume data suggest that a collapse in sea ice area could occur even sooner, as discussed on the AMEG blog posting."

Sea ice extent update August 14, 2012

The National Snow and Ice Data Center (NSIDC) at the University of Colorado has released an update. Excerpts follow below, for the full post, see A summer storm in the Arctic.

Arctic sea ice extent during the first two weeks of August continued to track below 2007 record low daily ice extents. As of August 13, ice extent was already among the four lowest summer minimum extents in the satellite record, with about five weeks still remaining in the melt season.

Arctic sea ice extent as of August 13, 2012. Credit: National Snow and Ice Data Center

The average pace of ice loss since late June has been rapid at just over 100,000 square kilometers (38,000 square miles) per day. However, this pace nearly doubled for a few days in early August during a major Arctic cyclonic storm, discussed below.

Unlike the summer of 2007 when a persistent pattern of high pressure was present over the central Arctic Ocean and a pattern of low pressure was over the northern Eurasian coast, the summer of 2012 has been characterized by variable conditions. Air tempertures at the 925 hPa level (about 3000 feet above the ocean surface) of 1 to 3 degrees Celsius (1.8 to 5.4 degrees Fahrenheit) above the 1981 to 2012 average have been the rule from central Greenland, northern Canada, and Alaska northward into the central Arctic Ocean. 

Cooler than average conditions (1 to 2 degrees Celsius or 1.8 to 3.6 degrees Fahrenheit) were observed in a small region of eastern Siberia extending into the East Siberian Sea, helping explain the persistence of low concentration ice in this region through early August.

August 6, 2012, 06:00 GMT surface weather analysis, showing a very strong cyclone over the central Arctic Ocean north of Alaska. The isobars (lines of equal pressure) are very tightly packed around the low pressure system, indicating strong winds. Greenland is on the right side of the figure, Canada at the bottom. Credit: Canadian Meteorological Centre

A low pressure system entered the Arctic Ocean from the eastern Siberian coast on August 4 and then strengthened rapidly over the central Arctic Ocean. On August 6 the central pressure of the cyclone reached 964 hPa, an extremely low value for this region. It persisted over the central Arctic Ocean over the next several days, and slowly dissipated. The storm initially brought warm and very windy conditions to the Chukchi and East Siberian seas (August 5), but low temperatures prevailed later.

On three consecutive days (August 7, 8, and 9), sea ice extent dropped by nearly 200,000 square kilometers (77,220 square miles). This could be due to mechanical break up of the ice and increased melting by strong winds and wave action during the storm.

The image below, from the Danish Meteorological Institute (DMI), shows that sea ice extent took a huge dive early August and has consolidated since, as the winds settled down.

Credit: Centre for Ocean and Ice, Danish Meteorological Institute

Note that, to calculate extent, DMI includes areas with ice concentration higher than 30% (NSIDC includes areas that show at least 15% sea ice). 

Another Arctic Cyclone brewing

Paul Beckwith fears that another Arctic cyclone could be starting up about 5 days from now. 

GFSx model shows it churning from about August 19th or 20th onward to the end of the forecast (at least for 5 days+). It appears that this storm will be positioned closer to the Atlantic side, and be north of Greenland. 

There will be a very high pressure mass of warm air over Greenland and the cyclonic flow will be pushing ice toward the Atlantic. Paul stands by his prediction of no sea ice in the Arctic by September 30th. There still is some 30 to 40+ days of melt season left. Paul adds that the 40+ days will more likely apply due to warmer water from storm churning.

Paul Beckwith, B.Eng, M.Sc. (Physics), Ph. D. student (Climatology); Part-time Professor, University of Ottawa

View Paul's presentation by clicking on the link below:
https://docs.google.com/open?id=0ByLujhsHsxP7dUQwYXJ6bXRSd00

Or, view the presentation in the window below (it may take some time for the file to fully load).

Getting the picture

Have a look at the picture below. It shows a graph based on data calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) developed at the Applied Physics Laboratory/Polar Science Center at the University of Washington.

image from arctische pinguin - click to enlarge

The PIOMAS data for the annual minimum values are the black dots. The trend (in red) is added by Wipneus and points at 2015 as the year when ice volume will reach zero. Note that the red line points at the start of the year 2015. The minimum in September 2014 will be already be close to zero, with perhaps a few hundred cubic km remaining just north of Greenland and Canada.

image from arctische pinguin - click to enlarge

Above image, again based on PIOMAS data, shows trends added by Wipneus for each month of the year. The black line shows that the average for the month September looks set to reach zero a few months into the year 2015, while the average for October (purple line) will reach zero before the start of the year 2016. Similarly, the average for August (red line) looks set to reach zero before the start of the year 2016.

In conclusion, it looks like there will be no sea ice from August 2015 through to October 2015, while a further three months look set to reach zero in 2017, 2018 and 2019 (respectively July, November and June). Before the start of the year 2020, in other words, there will be zero sea ice for the six months from June through to November.

Actually, events may unfold even more rapidly. As the ice gets thinner, it becomes more prone to break up if there are storms. At the same time, the frequency and intensity of storms looks set to increase as temperatures rise and as there will be more open water in the Arctic Ocean.

Above photo features Peter Wadhams, professor of Ocean Physics, and Head of the Polar Ocean Physics Group in the Department of Applied Mathematics and Theoretical Physics, University of Cambridge. Professor Wadhams has been measuring the sea ice in the Arctic for the 40 years, getting underneath the ice with the assistance of submarines, collecting ice thickness data and monitoring the thinning of the ice. This enabled 1970s data and 1980s data to be compared, which showed that the ice had thinned by about 15%. Satellite measurements only started in 1979.

Thinning of the ice is only one of the problems. "The next stage will be a collapse," Professor Wadhams warns, "where the winter growth is more than offset by the summer melt. If we look at the volume of ice that is present in the summer, the trend is so rapidly downwards that this collapse might happen within three or four years."

Apart from melting, strong winds can also influence sea ice extent, as happened in 2007 when much ice was driven across the Arctic Ocean by southerly winds. The fact that this occurred can only lead us to conclude that this could happen again. Natural variability offers no reason to rule out such a collapse, since natural variability works both ways, it could bring about such a collapse either earlier or later than models indicate.

In fact, the thinner the sea ice gets, the more likely an early collapse is to occur. It is accepted science that global warming will increase the intensity of extreme weather events, so more heavy winds and more intense storms can be expected to increasingly break up the remaining ice, both mechanically and by enhancing ocean heat transfer to the under-ice surface.

Recent events in the Arctic underline this warning. A huge cyclone battered the sea ice early August 2012. The image below, from The Cryosphere Today, shows a retreat in sea ice area to 3.09958 million km² on the 222^nd day of 2012, down from 3.91533 million km² on the 212^th day of 2012, i.e. 815,750 km² less in ten days. Or, more than one-fifth less in just ten days.

Image from  The Cryosphere Today - click to enlarge