About that melting arctic ice cap

Here’s one of the often shown graphics from the National Snow and Ice Data Center, showing extent (not area) of arctic sea ice:

While not quite chart junk, its clear message is an illusion.

  • The x-axis is not at zero, which exaggerates the change.  The ice extent range (y-axis) is only 12% over this 31 year period.
  • The bold blue trend line creates a strong bias, forcing the interpretation. 
  • In fact the 2010 value is aprox the same as that of 1996.  Flat for 14 years.
  • Looking at a graph of half this dataset (1995-2010) shows no obvious trend.
  • The small sample of 32 points tells us little, esp given natural long cyclical trends.  Esp data starting in the cold 1970’s.
  • The human eye is not good at detecting trends.  Which is why we have tests of statistical significance, the only reliable way to determine trends with serially correlated data like this.

Other perspectives on arctic ice history

These give more balanced perspectives, showing the brief data history (brief when looking at climatic trends), and the scale of the decline.

(a)  From the The IARC-JAXA Information System (IJIS):

The IARC-JAXA Information System (IJIS) is a geoinformatics facility for satellite image analysis and computational modeling/visualization in support of international collaboration in Arctic and global change research at the International Arctic Research Center in corporation with the Japan Aerospace Exploration Agency (JAXA). The red line is 2010. The melt has not yet begun, so the sea ice extent remains large. This graph can be found here; data through 16 April 2010.

(b)  From the Arctic Regional Ocean Observing System (Arctic ROOS)

The Arctic Regional Ocean Observing System (Arctic ROOS) has been established by a group of 14 member institutions from nine European countries working actively with ocean observation and modelling systems for the Arctic Ocean and adjacent seas.  This graph can be found here; it shows annual data through 2009.

 

For more Information about this topic

  1. The Changing Arctic“, George Nicolas, Monthly Weather Review, November — “so little ice as never before been noted. … Many old landmarks are so changed as to be unrecognizable. Where formerly great masses of ice were found there are now often moraines, accumulations of earth and stones.  Note the date of this article.
  2. Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols“, Mark Z. Jacobson, Nature, 8 February 2001
  3. Meteorological trends (1991-2004) at Arctic Station, Central West Greenland (69º15′N) in a 130 years perspective“, Birger U. Hansen, Bo Elberling, Ole Humlum & Niels Nielsen, Danish Journal of Geography, volume 106(1), 2006 – The arctic’s weather is changing in ways similar to that of the past 130 years.
  4. Impure as the Driven Snow“, Scientific American, 8 June 2007 — “Soot is a bigger problem than greenhouse gases in polar meltdown.”  This discusses “Present-day climate forcing and response from black carbon in snow”, Mark G. Flanner, Charles S. Zender, James T. Randerson, and Philip J. Rasch, Journal of Geophysical Research, June 2007 — Abstract.
  5. Experts Confirm Open Water Circling Arctic“, NY Times Science blog, 6 September 2008 — A somewhat balanced, in a confused way, article about arctic ice.
  6. NASA Still Spreading Antarctic Worries“, Steve Goddard, Watts Up with That, 3 February 2010 — The Antarctic data suggests these fears are without foundation (unlike the Arctic, where there are signs of warming).
  7. Wind contributing to Arctic sea ice loss, study finds“, The Guardian, 22 March 2010 — “New research does not question climate change is also melting ice in the Arctic, but finds wind patterns explain steep decline.”
  8. Arctic Sea Ice almost back to normal, Steven Goddard and Anthony Watts, Watts Up with That, 31 March 2010 

Other posts on the FM website about arctic sea ice

  1. George Will: climate criminal or brave but sloppy iconoclast?, 23 February 2009
  2. Aerosols (pollutionants, like soot) as a driver of climate change, 8 May 2009
  3. A look at the temperature record of Alaska – any sign of global warming?, 17 May 2009

Afterword

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