Current Events

  • Kansas Legislator Proposes Bill to Outlaw Sustainability Education
    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of ...Read more

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    Kansas Legislator Proposes Bill to Outlaw Sustainability Education

    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of sustainability. Here is a link to the one-page bill: http://www.kslegislature.org/li/b2013_14/measures/documents/hb2366_00_0000.pdf. See report on Bloomberg News.
  • Earth's Center Is 1,000 Degrees Hotter Than Previously Thought, Synchrotron X-Ray Experiment Shows
    Scientists have determined the temperature near the Earth’s center to be 6000 degrees Celsius, 1000 ...Read more

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    Earth's Center Is 1,000 Degrees Hotter Than Previously Thought, Synchrotron X-Ray Experiment Shows

    Scientists have determined the temperature near the Earth’s center to be 6000 degrees Celsius, 1000 degrees hotter than in a previous experiment run 20 years ago. These measurements confirm geophysical models that the temperature difference between the solid core and the mantle above, must be at least 1500 degrees to explain why the Earth has a magnetic field. For more information about this study, see the press release from the European Synchrotron Radiation Facility.
  • Ocean Volcanic Rocks Contain Samples of Recycled Crust
    Scientists have long believed that lava erupted from certain oceanic volcanoes contains materials fr...Read more

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    Ocean Volcanic Rocks Contain Samples of Recycled Crust

    Scientists have long believed that lava erupted from certain oceanic volcanoes contains materials from the early Earth’s crust. But decisive evidence for this phenomenon has proven elusive. New research from a team including Carnegie’s Erik Hauri demonstrates that oceanic volcanic rocks contain samples of recycled crust dating back to the Archean era 2.5 billion years ago. Their work is published in Nature. Oceanic crust sinks into the Earth’s mantle at so-called subduction zones, where two plates come together. Much of what happens to the crust during this journey is unknown. Model-dependent studies for how long subducted material can exist in the mantle are uncertain and evidence of very old crust returning to Earth’s surface via upwellings of magma has not been found until now. For more information about these results, see the press release from the Carnegie Institution.

Compare Images of Arctic Sea Ice Extent Side-by-side

The images below show sea ice in the Northern Hemisphere. Select images from the popup menus to compare two images side-by-side.

Try this:

  • compare the sea ice in March and September for the same year
  • compare the sea ice in March for two different years
  • compare the sea ice in September for two different years
  • click here if you want to look at sea ice in the southern hemisphere

Select a month:
... and a year:

Select a month:
... and a year:

The images are courtesy of the National Snow and Ice Data Center (NSIDC).

In the Northern Hemisphere (around the North Pole and the Arctic Ocean) the sea ice reaches its maximum extent in early spring, at the end of the long, cold winter. March is usually the month with the most sea ice.

The ice pack melts and breaks up over the summer. September is usually the month with the least sea ice (in the Northern Hemisphere).

The Northern Hemisphere ice pack seems to be shrinking, apparently as a result of global warming. The average rate of decrease in extent of the ice pack in September between 1979 and 2010 was 11.5% (+ or - 2.9%) per decade. Click here to see the predictions that global climate models make about future changes in sea ice extent.

The pink line in the images shows the average (from 1979 to 2000) edge of the ice pack for a particular month.

Click here to view an animation of the annual changes in sea ice extent in the Northern Hemisphere for a seven-year period (2002 through 2008).

Go to the NSIDC web site to:

Last modified October 8, 2010 by Randy Russell.

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