Percent of snow cover in North America over April 2010. Percent snow cover ranges from just above zero (light blue) to 100 percent (white). Land areas with no detectable snow cover during the month are gray. Photo by: NASA

By Jeremy Hance
www.mongabay.com
June 02, 2010 According to the National Oceanic and Atmospheric Administration, snow cover retreated to the lowest extent ever recorded in North America by the end of this April. Snow cover was 2.2 million square kilometers below average. With records of snow extent beginning in 1967, this is the lowest in 43 years and the largest negative anomaly in the past 521 months. A new image released by NASA shows just how little snow cover remained in April. Almost the entirety of Eastern and Midwestern United States is free of snow, while big chunks of Canada also lacked any snow cover. While scientists stress that a single weather event cannot be linked with certainty to global climate change, trends such as earlier springs (i.e., less snow cover during spring months) are not only expected under climate change, but have been recorded in many parts of the world. In addition to little snow cover in North America, April 2010 was the warmest April worldwide since record-keeping began in the late 19th Century: 0.76 degrees Celsius (1.37 degrees Fahrenheit) above the 20th Century average.

NASA satellite image reveals record low snow for the United States