Arctic could wreak havoc on Florida’s weather
Oct 18, 2012
The following article was published in the Sarasota Herald-Tribune on October 18, 2012:
By Kate Spinner
Forecasters say winter in Florida and along the southeastern U.S. coast will be wetter and a tad cooler than normal, but an unprecedented loss of Arctic sea ice this fall could wreak havoc with that prediction.
The experts made almost the same long-range forecast three years ago, based on Pacific Ocean temperatures similar to those expected to develop this year. But instead of a mild chill, Florida got record-breaking cold weather that winter.
If such extremely cold weather hits Florida again this winter, some scientists say the blame may lie nearly 3,000 miles away — in the Arctic Ocean. Sea ice there dropped to its lowest level ever recorded in September, shattering the previous mark set in 2007 by 16 percent.
Many climate scientists see a link between shrinking ice and unusual weather patterns that force Arctic air south instead of east for prolonged periods. The change can bring long-lasting winter weather extremes that cause droughts, floods and brutally long cold snaps.
But there is one big catch.
Although climate scientists expect Arctic air to venture south, they can’t say where. Florida might even end up warmer than normal.
“We’re not sure where the crazy stuff is going to set up,” said Jennifer Francis, a research professor at Rutgers University’s Institute of Marine and Coastal Sciences.
When sea ice shrinks, the Arctic can become warmer than normal, reducing the temperature difference between the North Pole and the equator. The temperature difference powers the jet stream — the river of air that drives weather around the globe. Without as much power, the jet stream meanders farther south than normal and can stay there for months.
“According to what our research has shown, the type of weather patterns that set up this fall should be more slow moving. They should stick around longer,” Rutger’s Francis said.
Unlike sea ice, the weather pattern called El Niño — caused by warmer than normal sea surface temperatures in the equatorial Pacific — has predictable effects on winter weather.
El Niño is predicted to take hold this winter, which usually causes the jet stream to push stronger rain and snow storms, and cooler air, farther south over the Eastern U.S. and Florida. That is the main reason forecasters are predicting a wetter and slightly cooler winter for Florida.
But sea ice measurements only go back to 1979, and scientists don’t yet see a definitive link between less Arctic sea ice and extreme cold in any particular place.
“There’s not a lot of sustained evidence that it’s consistently changing things from year to year,” said Paul Pastelok, head of long-range forecasting for Accuweather.com.
Pastelok acknowledges that the sea ice loss could throw a wrench in the forecast. He expects to see more extreme weather during winters that follow extremely low September sea ice coverage.
“My gut feeling is that it will have some impact,” Pastelok said.
The federal Climate Prediction Center also predicted a cooler and wetter Florida winter this year, but they did not have much confidence in their forecast Thursday. Their uncertainty stemmed from mixed signals over whether El Nino would form in time to affect winter weather.
The loss of Artic Ocean ice is likely to have some effect on weather if only because the ocean absorbed so much heat.
Ice reflects 80 percent of heat energy from the sun back into the atmosphere. Without the ice, the ocean absorbs 90 percent of that heat.
That heat has to go somewhere, explains Arctic climate scientist Julienne Stroeve, of the National Snow and Ice Data Center.
Sea ice was at its minimum coverage area on Sept. 16 before beginning to expand with the colder weather.
Once the ocean begins to freeze, the heat it absorbed is released into the atmosphere, creating an overall warmer Arctic.
It is that extra warmth that scientists say will shift weather patterns.
Francis said that due to the retreating ice, the ocean absorbed enough heat energy from the sun to meet U.S. energy demands for 26 years.
“It’s just an amazing amount of energy, so it’s really not a little thing at all,” Francis said.
View the original article here: http://www.heraldtribune.com/article/20121018/ARTICLE/121019555/2416/NEWS?p=all&tc=pgall