This summer marks the 4th year in a row — and the 4th time in recorded history — that the fabled Northwest Passage has opened for navigation. Indeed, 18 ships have travelled through this passage and cleared customs this year in Inuvik according to the Canada Border Services Agency. In 2009 the number was seven. It is also possible now to circumnavigate the Arctic through both passages in ice-free waters and this is the 3rd year in a row and the 3rd time in known history that this was possible. Indeed, a company, Beluga Shipping, was the first shipping company last year to transport goods in two ships from South Korea through the Northeast Passage to Siberia.
The polar explorers of the past would be astonished at how the Arctic looks today.
Normally, minimum sea ice in the Arctic occurs in mid-September before it starts to grow again during the long Arctic winter. According to the NSIDC minimum sea ice extent occurred about September 19 and was the third lowest in the data record, behind only 2007 and 2008. It was far less than the average extent from 1979 to 2000.
From a climate perspective what is important is not just extent, but sea ice volume, which gives a more complete idea of the warming occurring in the Arctic. Thin ice melts much more quickly than multi-year thick ice.
So let's look at ice volume as depicted in the graph. The cube on the left has a faint outline of the volume of summer Arctic sea ice in 1979. The inner and smaller dark cube schematically illustrates the amount in 2009. Note that the ice volume during that time has changed from 20,770 cubic kilometers to 7,958 cubic kilometers, a decrease of about 55%.
The right side of this chart graphs the "Changes in Sea Ice Volume" when the daily volume is compared with the 1979-2000 average for that day. This data is from an article in New Scientist 31 August 2010 by Chris Mooney. It should be noted that a PIOMASS model has been used for much of this work. It was developed at the University of Washington's Polar Science Center in Seattle. While the last several years data correlate well with ICESat satellite (which failed earlier this year) measurements, earlier years data are also consistent with earlier satellite, Navy submarine, moorings and field measurements data.
Let's not forget some other recent news accounts taking place in the Arctic. On August 4th 2010 a large chunk of the Petermann Glacier on Greenland broke off, which at this time is the largest iceberg in the northern hemisphere. It is about 150 square miles in size or about four times the size of Manhattan. It is so large that it might get stuck in Nares Strait, a narrow passage way between Greenland and Canada's Ellesmere Island, and not move south into the north Atlantic and its shipping lanes until it breaks apart into smaller chunks.
In 2008 another iceberg about 20 square miles in size broke off from this same glacier.
In mid August this year a huge chunk of ice about the size of Bermuda cracked off Canada's largest glacier, the Ward Hunt Ice Shelf. It has clung to the shores of Ellesmere Island for the last 3,000-5,000 years and contains the oldest sea ice in the northern hemisphere.
The science and data continue to be published. The permafrost area in the Arctic continues to decrease; methane releases from the tundra and its lakes appear to be increasing with attempts to measure this still underway; shoreline erosion continues to worsen as ice-in dates occur later in the fall; fish and other wildlife species are found further north than ever spotted before; pine bark beetles killing millions of trees in Alaska as the cold weather that kept them in check is no longer as cold.
The number of observed changes associated with global warming continues to increase. The energy imbalance is still there and with more energy entering our planet than is leaving, more changes will occur.
A lot more evidence of climate change is happening in the Arctic but more about that another time.
Note: The September 5, 2010 Climate Science article in the Press Republican was missing a critical chart. The article in its entirety can be found on the first page in ICSUSA.org.
The scientific career of Raymond N. Johnson, Ph.D., spanned 30 years in research and development as an organic/analytical chemist; he is currently founder and director of the Institute of Climate Studies USA (www.ICSUSA.org). Climate Science is published the first Sunday of every month.