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Should we worry about 2010′s near-record melting of sea ice?

10 July 2010

Summary:   No.  It’s weather, not climate change.  Many of the people sounding the alarms know they are exaggerating the situation.  This is a follow-up to It’s time to worry (again) about disappearing arctic ice (8 June 2010); see that for excellent graphs of the long-term sea ice history.

We’re told that polar sea ice is shrinking at an unusually rapid rate this year, and global warming is responsible.  This would be disturbing — if it were true.  In fact it is much ado about nothing.

Contents

  1. Polar sea ice is not shrinking at an unusually rapid rate this year
  2. The major short-term factor affecting arctic sea ice loss:   the wind
  3. Soot, one of the major long-term factor melting polar ice
  4. Other posts about earth’s melting ice, an afterword, and contact information

(1)  Polar sea ice is not shrinking at an unusually rapid rate this year

As explained in the June post:

  • Earth has two poles.   Cryosphere Today shows the area of global sea ice today is aprox at the 1979-2010 average.  Arctic sea ice is low; antarctic sea ice is above average. 
  • The rate of annual shrinkage does not correlate well with the size of the annual minimum.
  • The record of sea ice area goes back to 1979. It is too short a basis on which to draw strong conclusions due to the existence of long climate rhythms.

(2)  The major short-term factor affecting arctic sea ice loss:   the wind

Wind strength and patterns cause much of the annual variation in the minimum area and extent of the arctic ice.

(a)  The 2007 and 2010 declines in polar sea ice result mostly from winds.  The guilty party is The Arctic dipole anomaly, as explained by the National Snow and Ice Data Center, June 2010

The record low ice extent of September 2007 was influenced by a persistent atmospheric pressure pattern called the summer Arctic dipole anomaly (DA). The DA features unusually high pressure centered over the northern Beaufort Sea and unusually low pressure centered over the Kara Sea, along the Eurasian coast. In accord with Buys Ballot’s Law, this pattern causes winds to blow from the south along the Siberian coast, helping to push ice away from the coast and favoring strong melt. The DA pattern also promotes northerly winds in the Fram Strait region, helping to flush ice out of the Arctic Ocean into the North Atlantic. The DA pattern may also favor the import of warm ocean waters from the North Pacific that hastens ice melt.

June 2010 saw the return of the DA, but with the pressure centers shifted slightly compared to summer 2007. As a result, winds along the Siberian coastal sector are blowing more from the east rather than from the south. Whether or not the DA pattern persists through the rest of summer will bear strongly on whether a new record low in ice extent is set in September 2010.

The following material is from the June post about sea ice.

(b)  For non-technical explanations see these articles:

(c)  Some of the research about wind’s effect on the arctic, including the 2 studies described above:

(3)  Soot, one of the major long-term factor melting polar ice:

(a)  For non-technical explanations see:

(b)  Some of the large research literature about the effect on climate of soot (black carbon) deposits:

(4a)  Other posts about Earth’s melting ice

(4b)  Afterword and contact info

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