Arctic Sea Ice Volume Increases By 50%
Satellite data shows that Arctic sea ice was 50 per cent thicker in Autumn 2013 than it was in Autumn 2012, according to the US National Snow and Ice Data Center (NSIDC).
Data from the European Space Agency’s (ESA’s) CryoSat satellite which is equipped to measure the thickness of sea ice using radars shows that Arctic sea ice volumes grew by 50 per cent last year. This is due to an increase in ice thickness, since sea ice extent declined by around 3 per cent.
In a statement issued on 5 February, the NSIDC said: “Preliminary measurements from the CryoSat show that the volume of Arctic sea ice in autumn 2013 was about 50% higher than in the autumn of 2012. In October 2013, CryoSat measured approximately 9,000 cubic kilometers (approximately 2,200 cubic miles) of sea ice compared to 6,000 cubic kilometers (approximately 1,400 cubic miles) in October 2012.”
NSIDC data also shows that the decline in Arctic sea ice extent in January slowed to below the long-term rate of decline.
Over the last few decades, satellites have shown a downward trend in the area of Arctic Ocean covered by ice. However, the actual volume of sea ice has proven difficult to determine because it moves around and so its thickness can change.
According to ESA, CryoSat was designed to measure sea-ice thickness across the entire Arctic Ocean, and has allowed scientists, for the first time, to monitor the overall change in volume accurately.
About 90 per cent of the increase is due to growth of multiyear ice – which survives through more than one summer without melting – with only 10 per cent growth of first year ice. Thick, multiyear ice indicates healthy Arctic sea-ice cover, says ESA.
Multiyear ice at the end of 2013 was on average about 20 per cent, or around 30 cm, thicker than 2012.
“One of the things we’d noticed in our data was that the volume of ice year-to-year was not varying anything like as much as the ice extent – at least in 2010, 2011 and 2012… We didn’t expect the greater ice extent left at the end of this summer’s melt to be reflected in the volume. But it has been, and the reason is related to the amount of multiyear ice in the Arctic.” said Rachel Tilling from the UK’s Centre for Polar Observation and Modelling, who led the study into Arctic sea ice thickness, and was quoted in an ESA press release.