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Two individuals walk down Main Street in Westminster Feb 10, 2010.
Two individuals walk down Main Street in Westminster Feb 10, 2010. (Times file photo , Carroll County Times)

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:

Longer heat waves

In the last three summers, there have been 18 days with high temperatures of 100 degrees or warmer at Baltimore-Washington International Thurgood Marshall Airport in Anne Arundel County. There were just four 100-degree days from 2000-09.

National Weather Service weather observer Bobby Miller, of Millers, recorded a 102-degree high temperature July 22, 2011. It was the hottest temperature he recorded in 30 years of record keeping there. His previous high was 99 degrees.

Summertime cold fronts that bring relief to the heat and humidity and spark thunderstorms have struggled to travel over the Appalachian Mountains in recent years, MacCracken said.

With less cold air present in the higher latitudes due to climate change, fewer atmospheric clashes have existed, he said. Hence fewer July and August thunderstorms and extended heat waves, he said.

"We just haven't been getting triggers for thunderstorms to occur," he said. "So we get these drier periods."

It's been an unusually quiet tornado season nationwide for the last year. In the period from May 2012 to April 2013, just 197 tornadoes rated EF1 or stronger have been reported, the lowest for a 12-month period since records started being kept in 1954, according to a release from the NOAA Severe Storms Lab.

The previous record low for a 12-month period was 247 tornadoes during a period from June 1991 to May 1992.

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More powerful coastal storms

When Superstorm Sandy formed as a tropical system in the Atlantic Ocean last October, forecasters were alarmed by long-range models that predicted a powerful storm would batter the eastern seaboard.

Winter weather expert Paul Kocin, of the Weather Prediction Center in College Park, said in December that he canceled a vacation flight to Turkey so he could closely track the sort of storm that compared only to imaginary super storms he drew out as possible worst-case scenarios.

Forecasters watched as Sandy lost its tropical characteristics but pounded the New York and New Jersey coastline anyway with hurricane-force wind gusts and a powerful storm surge.

A powerful tropical system battering the East Coast is always a possibility, but it is quite unusual for a storm like this to strike the Eastern Seaboard in October, MacCracken said.

Warmer Atlantic waters and water vapor prevalent in the atmosphere help feed coastal storm systems, scientists said. If the planet does warm, the storms could increase and could be more powerful as they approach the East Coast.

Miller said he is concerned that the Chesapeake Bay region is vulnerable for a landfalling storm that could cause billions of dollars in damages.

Food supply concerns

Severe drought conditions continue in central and western Nebraska and Kansas, according to the latest update from the U.S. Drought Monitor.

It's an ongoing problem. Last year, areas from the Deep South to the Great Lakes suffered an extended drought that damaged crops.

More than 50 percent of the country's primary corn belt region from Minnesota to Kentucky are in the midst of moderate-to-extreme droughts.

Meanwhile, portions of the Midwest, which suffered through drought last year, have dealt with flooding this spring.

"It has caused farmers to delay their corn planting," said Chou, an analyst with the National Resources Defense Council. "They are going to plant more soybeans instead because the growing season has been shortened."

Climate change could lead to more extended droughts in areas of the country where, traditionally, crops and livestock are produced, MacCracken said.

"Farmers got pretty attuned on how to deal with the variability we have in the weather," MacCracken said. "In recent years, they have gotten pushed out of the range of weather they are used to."

He said farmers will have to adjust to changing climate conditions throughout the United States. It could also cause higher produce prices if enough crops are affected annually.

Drought has not been a significant problem in the mid-Atlantic. Miller has recorded an average of 53.12 inches of precipitation from 2008-12, more than 4 inches than in 2003-07 and 12 inches more than in 1998-2002.

Included in that total was the 6.1 inches of snow he recorded in the late October storm in 2011, one of several unusual weather events he's reported on in the last decade.

"A lot has happened in the last five years," he said.

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