Polar bears range from Russia to the U.S. (Alaska), from Canada to Greenland, and onto Norway’s Svalbard archipelago—the five polar bear nations.
Biologists estimate there are 20,000 to 25,000 bears. About 60% of those live in Canada.
At the 2009 meeting of the IUCN Polar Bear Specialist Group, scientists reported that of the19 populations of polar bears:
- 8 are declining
- 3 are stable
- 1 is increasing
- 7 have insufficient data
By comparison, in 2005:
- 5 were declining
- 5 were stable
- 2 were increasing
- 7 have insufficient data
In May 2008, the U.S listed the polar bear as a threatened species under the Endangered Species Act. In Canada, polar bears are listed as a species of special concern. Russia also considers the polar bear a species of concern.
What’s happening? Today, scientists have concluded that the threat to polar bears is loss of their sea ice habitat in the Arctic from global warming. Polar bears depend on sea ice for hunting, breeding, and in some cases, denning. Summer ice loss in the Arctic now equals an area the size of Alaska, Texas, and the state of Washington combined.
World’s First 3D Images of Snowflakes Falling
Curious History recently posted about the world’s first pictures of snowflakes ever taken in 1885 by William Bentley. We know have another first, the world’s first 3D images of snowflakes caught as they are falling.
Researchers at the University of Utah have teamed up with the National Science Foundation (NSF) to better understand just how fast and in what form snowflakes truly fall. To accomplish this, they used a high-speed Multi-Angle Snowflake Cam (aka “MASC”) to capture real-time 3D images of snowflakes in freefall at Utah’s Alta Ski Area.
The study is reportedly the first of its kind, and it’s already turning up some really interesting results.
Writes John Bohannon for Science NOW:
The classic image of a snowflake is a fluke. That flat, six-sided crystal with delicate filigree patterns of sharp branches occurs in only about one in every 1000 flakes. And a snowflake seen in 3D is another beast entirely. Researchers have developed a camera system that shoots untouched flakes “in the wild” as they fall from the sky. By grabbing a series of images of the tumbling crystals—its exposure time is one-40,000th of a second, compared with about one-200th in normal photography—the camera is revealing the true shape diversity of snowflakes.
Above is a tiny cross section of the variety of snowflakes MASC has photographed in free-fall so far. Check out tons more at the Snowflake Stereography and Fallspeed home page, or – when it’s snowing – at Alta Ski Area’s Snowflake Showcase, where you can watch a live feed of snowflakes falling in real time.