Showing posts with label Wipneus. Show all posts
Showing posts with label Wipneus. Show all posts

Tuesday, April 8, 2014

March 2014 Arctic Sea Ice Volume 2nd lowest on Record

The March 2014 Arctic sea ice volume, as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center, was the 2nd lowest on record at 21.818 km³. Only March 2011 had a lower volume, at 21.421 km³, as illustrated by the graph below, by Wipneus.
Another way of depicting the continued fall of the sea ice volume is the Arctic Death Spiral below, by Andy Lee Robinson.

This puts the sea ice in a very weak position. This month, the sea ice will reach its highest volume, which may well be the lowest volume on record for April. The Naval Reserach Laboratory 30-day animation below shows recent sea ice thickness.

The lowest sea ice volume for 2014 is expected to be reached in September, and - given the shape the ice is in now - will likely be one of the lowest minima on record. In fact, there is a chance that there will be no ice left whatsoever later this year. As illustrated by the image below, again by Wipneus, an exponential curve based on annual minima from 1979 points at zero ice volume end 2016, with the lower limit of the 95% confidence interval pointing at zero ice end of 2014.
Absence of sea ice will mean that a lot of more heat will be absorbed by the Arctic Ocean.

As describes, sea ice reflects 50% to 70% of the incoming energy, but thick sea ice covered with snow reflects as much as 90% of the incoming solar radiation. After the snow begins to melt, and because shallow melt ponds have an albedo of approximately 0.2 to 0.4, the surface albedo drops to about 0.75. As melt ponds grow and deepen, the surface albedo can drop to 0.15. The ocean reflects only 6% of the incoming solar radiation and absorbs the rest. Furthermore, all the heat that during the melt went into transforming ice into water will - in the absence of ice - be absorbed by the ocean as well.

Such feedbacks are causing warming to accelerate in the Arctic Ocean, much of which is very shallow and thus vulnerable to warming. The Gulf Stream can be expected to keep carrying warmer water into the Arctic Ocean. Extreme weather events such as heatwaves and cyclones could make the situation a lot worse.

Warming of the Arctic Ocean threatens to destabilize huge amounts of methane held in sediments at the seafloor, in the form of free gas and hydrates. The danger is that release of methane from the seafloor of the Arctic Ocean will warm up the Arctic even further, triggering even more methane releases, as well as heatwaves, wildfires and further feedbacks, in a spiral of runaway warming that will lead to starvation, destruction and extintion at massive scale across the globe.

In conclusion, the situation is dire and calls for comprehensive and effective action, as discussed at the climate plan blog.

Monday, August 13, 2012

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 222nd day of 2012, down from 3.91533 million km2 on the 212th 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