When it comes to climate change, the Great Lakes are considered by some to be the "canary in the coal mine."
The trends since the 1970s have been especially dramatic.
Ice coverage on Lake Superior has declined 79 percent since 1973.
During the winter of 2012, the lake had only 5 percent ice coverage.
A similar decline of ice cover has been reported on lakes throughout North America, Europe, and Asia.
There are several factors that have combined to limit the ice formation.
The average winter air temperature over Lake Superior has increased 5.0 F (2.7 C) since 1973.
The average water temperature increased 4.5 F (2.5 C) between 1979 and 2006.
For the past 60 years, the average amount of annual precipitation in the Lake Superior region
In addition, over the past few decades wind speeds have increased almost 30 percent.
Evaporation rates have intensified 17 percent.
Other climate change trends include:
-- Hotter summers and warmer winters.
-- Shorter winters and longer summers.
-- More mid-winter rain rather than snow.
-- More frequent and intense storms.
But the good news for agate hunting is that Lake Superior's lower level exposes more rock.
Even though there is less ice to bring new rock to our beach, there is still a 10,000 year supply of rock
NASA / Jeff Schmaltz, MODIS Rapid Response Team, GSFC
NOAA video http://www.glerl.noaa.gov/data/ice/atlas/daily_ice_cover/animations/animations.html
NOAA http://www.crh.noaa.gov/images/mqt/mar5_2010_big.jpg 2010
NASA / NOAA / NASA map by Robert Simmon image
EPA http://www.epa.gov/climatechange/impacts-adaptation/water.html and
U.S. Army Corps of Engineers,
Wiki / The Odd Gitt