The first day of Spring in Chicago is 60 degrees colder this year than last. Despite the wildly differing temperatures, both extremes could in part be due to the impact of the thinning of arctic sea ice upon the jet stream.
Actual High on March 20, 2012: 85 Degrees
Forecast High for March 20, 2013: 25 Degrees
Difference: -60 Degrees
Some researchers think the thinning arctic sea ice may be leading to a weakened, meandering jet stream. When the jet stream meanders to the north (2011-2012), the Midwest gets a mild, dry winter. When it meanders to the south as it has this month, the Midwest gets cold, snowy weather.
While the southern dip of the jet stream has led to cold, snowy weather in the Midwest, it has also produced near record warm weather for March in Greenland. Temperatures above the arctic circle have peaked above freezing on numerous days instead of hovering around 20 F degrees. Thus, the start of the arctic sea ice melt season is starting even earlier that usual. Given the early start of the melt, this year the arctic ice extent may again decline to record or near record lows. (Last year set a record low for arctic sea ice extent)
Here is where the reinforcing feedback loop could be coming into play. If the low extent of arctic sea ice is indeed leading to the meandering jet stream and the unusually warm above freezing temperatures above the arctic circle, this could lead to even more melting of arctic sea ice. The further reduction in arctic sea ice could have an more extreme impact on the weather in the future.
Admittedly, the above theory about climate change being in a reinforcing cycle is just speculation. We could just be the victims of fluky weather.