It just does not snow often in central Maryland in October.
So when 3 to 6 inches of snow fell in Carroll Oct. 29, 2011, on a day when McDaniel College's football team played its homecoming game in white-out conditions, local weather observers were flabbergasted.
Manchester weather observer Herb Close Jr. called it historic. It's the type of October snow we may never see again in our lifetimes, Deer Park weather observer Ralph Hartsock said.
More bizarre weather followed, including the hottest March on record, a powerful derecho in July and the landfall of Superstorm Sandy in October.
In the last five years, Carroll has registered its snowiest October, December and February on record. Two powerful named storms, Irene (2011) and Sandy (2012), caused flooding and wind damage. There's been record heat, tornadoes and hail. Snow has fallen when it typically does not.
Many scientists consider the out-of-whack extreme weather byproducts of climate change, which they believe is caused by humans increasing the amount of carbon dioxide in the atmosphere.
"The basic physics have been understood for decades," said Michael MacCracken, the chief scientist for climate change programs with the Climate Institute in Washington.
"Human activities are increasing the carbon dioxide in the atmosphere," he said. "Carbon dioxide in the atmosphere is a gas that tends to absorb infrared energy and radiate more back to the surface. The planet warms."
The amount of carbon dioxide in the atmosphere has reached an average daily level of 400 parts per million for the first time in at least 3 million years, according to a report from the National Oceanic and Atmospheric Administration released Friday.
Climate change skeptics are still prevalent. Joe Bastardi, the chief forecaster for WeatherBell.com and a frequent Fox News Channel guest, regularly rails against global warming on Twitter. He maintains that the global climate operates in cycles and that increased carbon dioxide released into the atmosphere does not affect global temperatures.
The exact long-term ramifications of climate change are debatable, said MacCracken, who has studied the effects of climate change for more than three decades.
"What climate change is going to mean exactly, we're still not sure," he said. "There are ranges of estimates."
So long as the planet continues to warm, the weather will be affected, altering growing schedules and increasing the risk of damage from powerful coastal storms, National Resources Defense Council water policy analyst Ben Chou said.
"A few weeks ago, they had torrential rain in the Midwest," he said. "There was widespread flooding where severe drought was taking place just last year. You just keep finding these images of extremes in many parts of the country."
Many scientists project climate change to continue so long as humans burn fossil fuels, meaning more extreme weather.
Scientists and forecasters highlighted potential consequences of climate change with regards to weather: