What global warming?

U.S., Europe feel big chill But climate change shows no end in sight, scientists say

LONDON — Where has global warming gone when we need it most?

As cities from Chicago to London deal with an unusually bitter winter, weather records show that 2008 was one of the cooler years in the last decade. And the early months of 2009 are shaping up as "numbing" in the United States, according to the Farmer's Almanac, that nearly 200-year-old source of traditional weather lore.

Britain this year has had its coldest start to winter in 30 years, with temperatures 5 degrees below average, but "this would have felt like a warm year as recently as the 1980s, and an exceptionally warm year in Victorian times," said Myles Allen, an atmospheric physicist at the University of Oxford.

In most parts of the world, "what we regard as normal weather is the average weather over the past 10 years," he said. "We forget what it was like before then," even if someone occasionally drags out old photos of houses roof-high in snowdrifts or tales of slogging miles to school in near-impassible conditions.

Britain's recent deep freeze —its coldest spell since 1996—is due to stalled weather patterns that have funneled in frigid air from Siberia and from continental Europe, which is also shivering after years of unusually mild winters, according to the Hadley Center, the United Kingdom's leading weather service.

Stalled or unusual weather patterns also have contributed to remarkable snow and cold in Chicago and across much of the United States this winter. So far, this winter has been the 22nd coldest in 139 years of record-keeping in Chicago, and the fourth-snowiest in 124 years of records, according to Tom Skilling, chief meteorologist at WGN-TV. On Thursday, Chicago could see its first subzero high temperature in nearly 13 years.

"Just because certain areas cool down in the midst of an overall warming trend doesn't mean warming isn't going on," Skilling said. But the intensity of the cold and snow over the past two winters is raising some questions about how well scientists understand the interaction of an array of weather-changing forces, from sunspots to volcanic activity.

For instance, one reason the last two winters have been chillier than normal, climate scientists say, is a cyclical change in Pacific Ocean currents known as La Nina. In La Nina years, cold ocean currents rise to the surface near the equator, often causing cooler winters in northern regions like the United States. An opposite warming effect occurs in El Nino years.

Meteorologists say La Nina phase in the Pacific is now ending, and some predict that by 2010 the world should again be seeing some of the warmest years on record—warm enough that the Hadley Center is warning that poor residents of Britain may need help paying air-conditioning bills this summer.

But other meteorologists see evidence of an unusual second La Nina on the rise in the Pacific, which could extend the current stretch of colder-than-average winters.

"It's a very complex puzzle, this whole climate thing," Skilling said.

Snowfall in Chicago in recent years still isn't anything approaching the snowy winters of the 1970s, when the Chicago average was 54 inches, Skilling said. But he said graphs his research department has drawn up suggest "we're cycling back into an era of a little more snow."

Whether that is a simply a temporary break from a long-term rise in planetary temperatures or a new, not-well-understood winter trend isn't entirely clear. But "the fact that 2009, like 2008, will not break records does not mean that global warming has gone away," warned Phil Jones, director of climate research at the University of East Anglia in England.

In fact, "when you step back and look at the bigger picture, the overwhelming evidence is that temperature is increasing around the world," said John Hammonds, a meteorologist with the Hadley Center.