Some proponents of climate science are on a public relations drive to restore public confidence in the consensus that Earth is heating up, after critics seized on blizzards in the American Northeast, claiming they were evidence of global cooling.
Speaking to reporters, Jeff Masters, a meteorologist and founder of the Weather Underground web site, said that one extreme weather event, like a record-breaking snowfall, does not change the reality of climate change.
"Record snowstorms being evidence against global warming is just not true," said Masters, whose site gets 18 million visitors per month.
Various U.S. green groups and progressive organizations, including the Center for American Progress, the National Wildlife Federation and the Union of Concerned Scientists, have similarly been working to clear the confusion surrounding the extreme freeze.
That's because from the other side of the debate, global warming skeptics in Washington have used the snowstorms to try to shore up their campaign against climate change legislation in Congress. Relatives of Sen. James Inhofe (R-Okla.), one of the nation's most vocal climate change deniers, built an igloo last week near the U.S. Capitol with a sign, "Honk if You [Heart] Global Warming."
Masters conceded that the heavy storms in the Northeast were "unprecedented" since modern temperature measurement began in 1880. But weather, which refers to day-to-day temperature, is not the same as climate, which includes other factors like humidity and precipitation over a long period of time.
Understanding whether the planet's temperature is on an upward path requires analysis of data going back three decades or more, he said.
For Masters and others, the long-term picture is clear: "The climate is changing, and it's warming," Masters said.
• According to numbers from the NASA Goddard Institute for Space Studies, global average surface temperatures have shot up about 1.5 degrees Fahrenheit since 1880, with much of that jump occurring over the past 50 years.
• The World Meteorological Organization (WMO), a United Nations agency, said in December that the 10 years ending in 2009 was likely the warmest decade on record. Previously, the hottest decade was the 1990s; before that it was the 1980s.
• In January, NASA announced that 2009 tied for the second warmest year on record after 2005.
Despite the science, confusion over winter weather is threatening "to turn people away from thinking that global warming is real," said Masters.
Snowstorms Consistent With Warming?
Climate scientists across the spectrum agree on one thing — that a single extreme weather event, such as a cold spell, heat wave or flood, cannot prove or disprove climate change.
Some go father and insist that such extremes are consistent with a warming planet.
"Climate change projections show that a warming planet generates more precipitation in areas that typically experience rain or snow," said the Union of Concerned Scientists (UCS), a private group that supports greenhouse gas regulation.
According to the Northeast Climate Impact Assessment, a collaboration between UCS and some 50 scientists and economists, winter precipitation in the Northeast jumped 0.15 inches per decade over the past several decades as the planet heated up.
Brenda Ekwurzel, a climate scientist with the UCS, said that scientists "aren't at all surprised" that there are more rain storms and blizzards in certain parts of the country. "That's consistent with well-documented climate change trends over the past several decades," she said.
Advocates of the position say the reason is an increase in air moisture, a result of the boost in ocean surface temperatures.
"We know that the moisture levels of the atmosphere have increased by about four percent globally over the past 40 years due to the fact that the globe has warmed," said Masters. "There's a possibility now that this extra moisture can be made available for snowstorms to make them heavier."
Not all climate scientists would share this view, however.
Kenneth Kunkel, executive director of the Division of Atmospheric Sciences of the Desert Research Institute, said there "might be some circumstances" where he "would be comfortable" making the statement that extreme weather is "consistent with" global warming, but February's heavy snowfall is not one of them.
"I am not aware that climate models indicate more extreme snowfall events along the East Coast," Kunkel who manages a team of 120 atmospheric scientists, told SolveClimate. "There has been little work on potential future changes in extreme snowfall events."
"The general idea that climate change will cause all types of weather phenomena to become more extreme is not correct," he added.
Philip Duffy, the scientific director of Climate Central and a physicist from the Lawrence Livermore National Laboratory, told SolveClimate that the extreme weather that blanketed the Northeast "probably was" due to climate change. But, he added, "you can never say for sure. Big storms do sometimes happen absent climate change."
As a general rule, however, Duffy said that "precipitation increases through climate change" and "the amount of precipitation in individual storms also increases."
National Oceanic and Atmospheric Administration (NOAA) chief Jane Lubchenco also talked about the storms and climate change Monday on NPR. The snowstorms aren't a contradiction with climate science, nor are they unexpected, she explained. Weather is highly variable, and this year's weather is influenced by El Nino sending wet, stormy weather across the southern United States and the Arctic oscillation pushing cold air down from the Arctic.
"It's important that people recognize that weather is not the same as climate, and record-breaking storms neither negate nor prove climate change," Lubchenco said.
Erring on the Side of Caution
Masters suggested that while "extreme events are not necessarily connected to climate change" and "a lot of what we're seeing is natural variability," it is better for governments to err on the side of caution.
"We need to be concerned about the future," said Masters.
His view echoes that of some of the world's largest meteorological societies.
The American Meteorological Society (AMS) said in its 2007 statement that "precipitation is expected to become more intense" due to climate changes. "Prudence dictates extreme care in managing our relationship with the only planet known to be capable of sustaining human life," the group wrote.
Two years later, the AMS, along with 17 other scientific organizations, delivered U.S. senators a letter outlining the "consensus scientific view." The group said the "severity of climate change impacts is expected to increase substantially in the coming decades," including extreme weather events. They called for a dramatic curbs in planet-warming greenhouse gases.
Similarly, last November, in advance of the Copenhagen climate conference, the Met Office, NERC and the Royal Society, three of Britain's leading scientific organizations, said in a particularly strong statement, "we cannot emphasize enough the body of scientific evidence that underpins the call for action now."
"Year on year the evidence is growing that damaging climate and weather events — potentially intensified by global warming — are already happening and beginning to affect society and ecosystems," they said.
The group wrote that "in the absence of action to mitigate climate change," much larger changes than the world has seen so far will be felt in the coming decades.
(Photo Courtesy of Carolyn Wise)