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Hints of an Arctic Pause? 2007 – 2013

Posted By Joanne Nova On April 4, 2015 @ 7:43 pm In Global Warming | Comments Disabled

Another excuse may be on the rocks. The Arctic ice melt has been a favorite clarion of catastrophists. What will they do if it stops declining? It is early days, but if the missing heat is hiding in the Arctic this pattern is not following the green machine plan.

David Whitehouse GWPF

A New “Pause?”

Examining the sea ice extent data for the past eight years it is obvious that there has not been any statistically significant downward trend, even though there is more noise (interannual variability) in the data. There are interannual variations but they do not form a trend. For the 2002 – 2006 period the annual differences are mostly in the extent of maximum and not minimum ice cover. The period 1990 – 1996 displays much more interannual variability. The main difference between the ice-curves is that in recent years there has been an increase in the gradient around the beginning of June.

Of the general decline and the interannual variability how much is due to external forcing and how much to internal variability? Estimate from climate models give about equal measure to forcing and internal variability, Kay et al (2011), Stroeve et al (2012). That 50% internal variability is almost never illustrated graphically when presenting Arctic ice data.

That the minimal extent of Arctic ice has “paused” is admitted by Swart et al (2015)

“…from 2007–2013 there was a near-zero trend in observed Arctic September sea-ice extent, in large part due to a strong uptick of the ice-pack in 2013, which has continued into 2014.”

Swart et al (2015) maintain that “cherry-picking” such short periods can be “misleading about longer-term changes, when such trends show either rapid or slow ice loss.”

- See more at: http://www.thegwpf.com/arctic-ice-decline-a-new-pause/#sthash.etgq6yJ2.dpuf

The Australian

Melting Arctic sea ice, a keenly watched measure of global clim­ate change, has “paused”, sharpening debate on whether humans or natural variability are to blame for the earlier decline.

After shrinking 35 per cent over several decades, the low point reached in Arctic ice cover each year appears to have stabilised. This is despite a record low maximum ice extent this winter and new research that shows the annual melt was beginning days earlier each decade.

Scientists who first identified the “hiatus” in global average surface temperatures are claiming a new climate change “pause”.

Summer melts are still retreating to levels that put them at the extreme low end of the relatively short satellite record and attention increasingly is being focused on the loss of ice thickness.

But the “pause” in summer ice melt extent has been widely ­conceded. A paper published in ­Nature by Neil Swart from Environment Canada said “from 2007-13 there was a near-zero trend in observed Arctic September sea-ice extent, in large part due to a strong uptick of the icepack in 2013 which has continued into 2014”.

 

REFERENCE

Swart et al (2015) Influence of internal variability on Arctic sea-ice trends, Nature climate Change, 5, Pages: 86–89 DOI: doi:10.1038/nclimate2483

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