BOULDER, Colo., Jan. 24 (UPI) -- Much of the nation was firmly in Mother Nature's cold grip Friday and many people quipped that it sure didn't feel much like global warming.
"Dangerous and bitterly cold temperatures seeping down from the Arctic region have plunged most of the nation into a deep freeze," The National Weather Service noted.
Temperatures might be cold for much of the nation right now but they do not argue one way or the other for the long-term affects of global warming on the climate, according to scientists who both assert and dismiss the idea man-made pollution is causing a global warm-up.
Kevin Trenberth, head of climate analysis for the National Center for Atmospheric Research in Boulder, Colo., told United Press International, "Global warming is a very gradual process, and in any year it can be overwhelmed by any weather pattern."
Myron Ebell, director of global warming policy for the Competitive Enterprise Institute, says the current cold snap "tells us nothing about whether climate is changing."
Ebell told UPI he does find it curious, though, that "whenever we have a heat wave, the major news outlets, like The New York Times and the networks, talk about global warming but they get very quiet when we have these periods of prolonged cold."
Trenberth said, "One shouldn't look just at the cold in the East, but at the warm in the West. This is a wave pattern that gets set up by El Nino."
Conditions in the West, he said, were very warm in December and dry and warm early in January.
"We've had days in the 60s and 70s in January. This is very remarkable. There has been next to no snow and rain since November," Trenberth said.
The Midwest also has been cold but Don Wylie, a cloud climatologist at the University of Wisconsin-Madison, said despite the cold spell "statistically, Madison is still averaging above normal. We had a warm period around the start of the month."
The weather, Wylie said, is related neither to global warming nor to El Nino. "It's just typical January weather," he told UPI.
Statistically, Wylie said, scientists studying global warming are looking for a small effect in a system with large normal variations.
"When you start moving outside the envelope of what you've observed," he said, "you're on thin ice."
The National Weather Service reported a sagging jet stream has allowed a massive area of cold air from Siberia to sink farther south and into the United States.
Trenberth said El Nino -- which is a warming of the Pacific Ocean waters that affects climate mostly in the western hemisphere -- "changes the heating patterns and influences the jet stream and storm tracks in the upper atmosphere."
Wylie said, however, current patterns are not typical of El Nino at all. "El Ninos are full of variability," he said. "I said, 'Watch for a cold November.' Our ski hills opened early this year. But we have only half an inch of snow more than the driest winter on record. Nobody is going cross-country skiing."
Wisconsin has had three days in the 50s. "We've set a lot of warm records, but we haven't set any cold records. They've all been set in the southeast," he added.
Mike Halpert, a meteorologist at the NOAA Climate Prediction Center, said the climate phenomenon El Nino is not responsible for the cold air outbreak.
"If anything, this cold pattern is not typically experienced during El Nino periods -- at least not the past few El Ninos," he said.
The NWS is predicting a moderate warming trend east of the Rocky Mountains over the next week.