Arctic Sea Ice Extent
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This is a brief look at the Arctic sea ice extent using data
from IRAC JAXA. Firstly, the sea ice extent is plotted as a time
Unfortunately this data set is rather short, but nonetheless
shows the unusually high melt season of 2007. Based upon this limited time
frame, it would appear that the extremes are moving apart with increasing extent
in winter and less ice in summer.
Calculating the annual rate of change yields the following:
This is an interesting plot and reveals that the summer of 2007
as somewhat unusual.
However, more surprisingly given all the media noise about
the Arctic ice disappearing, the rate of change is presently on an upward
trend. The Arctic sea extent is not just increasing but accelerating!
It is important to keep in mind that this data set is short
and may not be wholly representative of the long term situation. That said,
according to official sources ice LOSS is accelerating, but the data tells the
opposite story; Arctic Sea Ice Extent is INCREASING and accelerating.
A more detailed analysis can be found here in which the following conclusions are made:
Reconstructions of sea ice extent show no obvious decline until the advent
of the satellite.
The claim that Arctic sea ice extent has been declining since 1953 is
unjustified since there was no significant decline until 1979 when it exceeded
1 standard deviation below the 1953 to 1978 mean.
The satellite sensors drift, and as has been aptly displayed by SSM/I
recently, there is at least one failure mode that results in underestimation
of the sea ice extent.
The proclaimed unprecedented Arctic sea ice melt of 2007 does not appear
particularly unusual and a similar but much more severe episode occurred in
1995, although at that time the measurements showed a higher starting
Presently, based upon the reportedly “most accurate” satellite data from
AMSR-E (IRAC JAXA), Arctic sea ice
extent is increasing at an accelerating rate.
Significant differences in winter ice extent are observed between NASA team
SSM/I and AMSR-E IRAC JAXA during the
overlapping period that might be explained by differing algorithms.
NASA team SSM/I shows a decline in extent relative to AMSR-E IRAC JAXA that might account for a
substantial proportion of the apparent Arctic sea ice loss since the start of
the satellite surveys.
A pdf version is available here.
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