If the Earth is getting warmer, why's it so darn snowy and cold?
Are the U.S. winter extremes proof that global warming isn't happening or is even a hoax, as some skeptics suggest? Or are the winter extremes a product of a warming atmosphere, as many climate change advocates assert?
While opinions about climate change vary greatly, even among experts in climate science, the consensus is that short-range weather events have little to do with the climate change debate.
There's no debating that it's been cold, especially in January. According to Deke Arndt of the federal National Climatic Data Center, "January 2011 will rank among the coldest 20 percent of Januarys on record since 1895." December brought the coldest temperatures on record to parts of South Florida, although the month averaged near normal for the nation as a whole because the Southern cold was balanced by warmth elsewhere.
There's also no debating that there's been plenty of snow. A record 36 inches fell in Central Park in January, crushing New York City's old record of 27.4 inches set in 1925. Snowfall records also fell last month elsewhere in the Northeast, while blizzards hit the Midwest and a major snow and ice storm swept through the Deep South.
"I believe the events we are seeing are entirely natural," Roy Spencer, a meteorologist and Principal Research Scientist at the University of Alabama in Huntsville, told AOL News. "Persistent storminess in one location means someplace else is having unusually quiet weather. One of the reasons we know this is [that] our global precipitation measurements from satellites show that the total amount of precipitation that falls on the Earth remains almost exactly the same, year after year."
Spencer said global temperatures have been falling for about the past 12 months. "The global average is now approaching the long-term normal," he said.
Spencer is a skeptic of man-made global warming, noting on his website that climate changes occur with or without our help.
Even experts who have contributed -- or will contribute -- to the United Nations' Intergovernmental Panel on Climate Change (IPCC) also believe this year's winter weather extremes cannot be directly attributed to large-scale climate changes. The panel has been outspoken about climate change caused by human activity.
"Since climate change is by definition the long-term change in weather, it is not possible for a quality scientist to say that any given event is directly related to climate change," the University of Illinois' Donald Wuebbles told AOL News. Wuebbles was a lead author on the first and second international assessments of climate change for the IPCC.
Dennis Hartmann, an atmospheric sciences professor at the University of Washington and future lead author of the IPCC's upcoming assessment, concurs.
"I don't think we have the capability to attribute one year's extreme event to greenhouse gas increases," he told AOL News. "If you have an unprecedented extreme event, or several of them, for which we have a good physical argument for why human-induced climate change is the cause, then I could see attribution of an extreme event to human activity. But this winter is probably not one of those."
When looking at the long term, which is what is needed to assess a change in the climate, Wuebbles says that we need to ask whether the events in question would have happened if it weren't for changes in climate that are occurring. "We do know that a warmer atmosphere can hold more water vapor, leading to the possibility of large rain- or snowstorms, but also potentially leading to more heat waves in the summer."
Even if global temperatures fall to below-normal levels for a month, it would not be viewed as an important trend by climate scientists.
"Based on the past record, it seems like it takes more than a decade to establish a significant change in the overall trend," Hartmann said. "We have already seen several flat periods in an otherwise upwardly trending global mean temperature."
There's no doubt that the debate about climate change, especially as it is related to human activity, will continue, but it will never be settled based on one season.
Of course, we don't hear from our favorite groundhog, Punxsutawney Phil, until dawn Wednesday.