Signs From Earth

Lasers Show Thinning at Edges of Big Ice Sheets

The British Antarctic Survey has been using laser beams to determine the thickness of ice in the big sheets in Greenland and Antarctica. The scientists have found that the ice is thinning quickly along the coasts. This can be seen in red in the map above.

This report was published in the journal Nature, more info and links to the paper, pictures, maps, and PR releases are here: Space Lasers Show Greenland and Antarctic Ice Sheets Aren't What They Used to Be.

Potential implications of melting from ice sheets are explored in a New York Times article on the loss of large sections of Vietnam's Mekong Delta from sea-level rise, and another in the Financial Times Sept. 23 on similar threats to Bangladesh, a low-lying delta region at the end of the Ganges River. A study in Nature Geoscience has explored the vulnerability of river deltas worldwide to sinking and sea rise.

2009 Arctic Ice Melt Compared to Earlier Years

The chart above from the National Snow and Ice Data Center shows extent of ice melt in 2009 (light blue line) compared to earlier years. The greatest melt occurred in 2007 (dotted green line), and this year's melt is third most significant behind 2008 (dark blue line,) which was second. The 2005 melt is shown in solid light green. The Arctic ice appears to be in a new phase, with more significant melt in the past three years than the average for the period 1979-2000, which is show in gray in the upper part of the chart.

As reported by NSIDC, the minimum extent in 2009 is 24 percent below the 1979-2000 average minimum and 20 percent below the 1979-2008 average minimum. Extent is not the only measure, as younger, thinner ice dominates now, and it is more vulnerable to melting.

2009 Global Temperature Trends: January – August

 

The National Climatic Data Center has (finally) released global temperature trends data for the first eight months of 2009, and the red dots on the map show that most of the world keeps running a fever. According to records of combined land and sea temperature observations the period from January through August 2009 is the fifth warmest on record.

Specifically for August, NCDC reports that ocean temperatures worldwide for August are the warmest ever measured since record keeping began.

Those in the middle of the blue dot area on the map in North America or in the far southern ocean near Antarctica might be forgiven if they thought their local world was cooling, but one must keep the long term trend in mind and remember that the map clearly shows a lot more big red dots than big blue dots. 

That means the world was warmer than average, and in some places by quite a bit when you look at the many fat red dots over Mexico, Africa, China, India, Australia, and California. It should be noted that several of these regions have also been suffering droughts, and research shows that these continuing warming trends will most likely drive long-term water shortages.

This warming trend is useful to examine in connection with the chart below showing how 2009 compares to earlier years. All years since 1980 have been above the norm (red)  and the last time a year was below the norm (blue) was 1976. It is also useful to keep in mind that we have been seeing significant loss of Arctic sea ice, as the Arctic Ocean loss of ice in 2009 was the third most significant on record behind 2007 and 2008 according to the National Snow and Ice Data Center. 

Arctic Sea Ice Melt Trend Near 2007 Level

The graph below from July 28, 2009 and released today from National Snow and Ice Data Center shows Arctic Ocean ice melt trend (blue line) close to 2007 levels (green line), which were a record. 

Last year's melt was the second most severe, and on a week ago the NSIDC reported that this season's ice melt was trending slightly ahead of 2008 levels. See Signs From Earth: Global Temperature Trends for First Half 2009 and Arctic Melt Season in "High Gear."

The summer melt season runs for about another month. The graph below and a more extensive map (above) of sea ice extent and trends are updated daily at the NSIDC website. The orange line on the July 28 map above shows average extent of sea ice for the period from 1979-2000, which is also the top line on the trend graph below.

Flash! Secret Ice Images Revealed (As Reported Here 10 Days Ago)

 

For what it is worth, the breathless July 26 headline in the London Observer, "Revealed: The Secret evidence of global warming Bush tried to hide," seems over the top, and late to the game. 

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One wonders where the major news outlets in the United States have been on this story, which was written about right here at Signs From Earth on July 16 after Jenny Lauren Lee at Science News in Washington posted an item there on July 15. 

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Details and pictures here: Secret Pictures of Arctic Ice Released. Now that the "major" news outlets are picking up this story, we can now believe that it really happened. Thank goodness.

Sea Ice Swirls along Baffin Island, Canada

In this July 11, 2009 satellite image from NASA Earth Observatory, the delicate swirls along the southeast coast of Baffin Island are floating ice moving with the ocean currents. Eddies along the east coast of this large island between North America and Greenland have fashioned the floating ice into interlocking swirls. 

Arctic ice is nearing the peak of its melt season, and the National Snow and Ice Data Center reports that overall ice loss this summer is on par or greater than the 2008 melt, which was the second greatest melt season on record behind 2007. Earlier this month researchers reported that Arctic ice is also younger and thinner.