changes in global ice
Climate change can dramatically affect amounts of snow and ice in an area, because a very small change in temperature can melt large amounts of snow and ice. Arctic sea ice has decreased in size and thickness, reaching a record low in September 2012. The melting of glaciers has both reduced global ice and increased sea levels. Lakes in the northern United States are freezing later in the year and thawing earlier in the year. Snowfall has been decreasing since 1930, falling as rain instead of snow. Snow cover in North America has decreased at a rate of around 3,500 square feet per year since 1972. Snow depth has decreased in 75% of the USA since 1955. In Alaska, two major rivers, the Tanana River and the Yukon River, have had their ice breaking earlier in the spring than they used to ("Climate Change Indicators in the United States: Snow and Ice," n.d.).