Climate-change skeptics pounce

The world has seen some extraordinary winter conditions in both hemispheres over the past year: snow in Johannesburg last June and in Baghdad in January, Arctic sea ice returning with a vengeance after a record retreat last summer, paralyzing blizzards in China and a sharp drop in the globe's average temperature.

It is no wonder that some scientists, opinion writers, political operatives and other people who challenge warnings about dangerous human-caused global warming have jumped on this as a teachable moment.

"Earth's 'Fever' Breaks: Global COOLING Currently Under Way," read a blog post and news release on Wednesday from Marc Morano, the communications director for the Republican minority on the Senate Environment and Public Works Committee.

So what is happening?

According to a host of climate experts, including some who question the extent and risks of global warming, it is mostly good old-fashioned weather, along with a cold kick from the tropical Pacific Ocean, which is in its La Niña phase for a few more months, a year after it was in the opposite warm El Niño pattern.

If anything else is afoot — like some cooling related to sunspot cycles or slow shifts in ocean and atmospheric patterns that can influence temperatures — an array of scientists who have staked out differing positions on the overall threat from global warming agree that there is no way to pinpoint whether such a new force is at work.

Many scientists also say the cool spell in no way undermines the enormous body of evidence pointing to a warming world with disrupted weather patterns, less ice and rising seas should heat-trapping greenhouse gases from burning fossil fuels and forests continue to accumulate in the air.

"The current downturn is not very unusual," said Carl Mears, a scientist at Remote Sensing Systems, a private research group in Santa Rosa, Calif., that has been using satellite data to track global temperature and whose findings have been held out as reliable by a variety of climate experts. He pointed to similar drops in 1988, 1991-92 and 1998, but with a long-term warming trend remaining clear nonetheless.

"Temperatures are very likely to recover after the La Niña event is over," he said.

Morano, in an e-mail message, was undaunted, saying turnabout is fair play: "Dissenters of a man-made 'climate crisis' are using the reality of this record-breaking winter to expose the silly warming alarmism that the news media and some scientists have been ceaselessly promoting for decades."

More clucking about the cold is likely over the next several days. The Heartland Institute, a public-policy research group in Chicago opposed to regulatory approaches to environmental problems, is holding a conference in New York on Monday and Tuesday aimed at exploring questions about the cause and dangers of climate change.

The event will convene an array of scientists, economists, statisticians and libertarian commentators holding a dizzying range of views on the changing climate — from those who see a human influence but think it is not dangerous, to others who say global warming is a hoax, the sun's fault or beneficial. Many attendees say it is the dawn of a new paradigm. But many climate scientists and environmental campaigners say it is the skeptics' last stand.

Michael Schlesinger, an atmospheric scientist at the University of Illinois, Urbana-Champaign, said that any focus on the past few months or years as evidence undermining the established theory that accumulating greenhouse gases are making the world warmer was, at best, a waste of time and, at worst, a harmful distraction.

Discerning a human influence on climate, he said, "involves finding a signal in a noisy background." He added, "The only way to do this within our noisy climate system is to average, over a sufficient number of years, that the noise is greatly diminished, thereby revealing the signal. This means that one cannot look at any single year and know whether what one is seeing is the signal, or the noise, or both the signal and the noise."

The shifts in the extent and thickness of sea ice in the Arctic (where ice has retreated significantly in recent summers) and Antarctic (where the area of floating sea ice has grown lately) are similarly hard to attribute to particular influences.

"Climate skeptics typically take a few small pieces of the puzzle to debunk global warming and ignore the whole picture that the larger science community sees by looking at all the pieces," said Ignatius Rigor, a climate scientist at the Polar Science Center of the University of Washington.

He said the argument for a growing human influence on climate laid out in last year's reports from the Intergovernmental Panel on Climate Change (IPCC) was supported by evidence from many fields.

"I will admit that we do not have all the pieces," Rigor said, "but as the IPCC reports, the preponderance of evidence suggests that global warming is real." As for the Arctic, he said, "Yes, this year's winter ice extent is higher than last year's, but it is still lower than the long-term mean."

Rigor said next summer's ice retreat, despite the regrowth of thin fresh-formed ice now, still could surpass last year's, when nearly all of the Arctic Ocean between Alaska and Siberia was open water.