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"Climate change is happening at a much greater and accelerated pace than we ever expected 30 years ago," said Richard Leopold, director of the Iowa Department of Natural Resources. Huge floods in 2008, which left the state's second-biggest city, Cedar Rapids, with massive downtown destruction, intensified the debate, with a new set of recommendations coming from a state panel by the end of the year. "If we decide as a state to significantly reduce greenhouse gas emissions in a hurry, we can actually do it," said Sen. Rob Hogg, a Democrat from Cedar Rapids. "There are a lot of things we can do for no cost, and others we can do for very little cost."

Summer storms already can be more intense, and the Midwest has fought to avoid major flooding this year.

The records Takle analysed showed Iowa averages five more frost-free days a year than in 1950. But that doesn't mean more time to grow crops, because of changes in temperature and precipitation patterns. Generally, Iowa now has warmer winters, but fewer extremely hot summer days. Overall, the Midwest is expected to warm through the middle of the century, but not as much as other parts of the country.

Large-scale storm systems are the dominant weather phenomenon during the cold season in the United States. Although the analysis of these storms is complicated by a relatively short length of most observational records and by the highly variable nature of strong storms, some clear patterns have emerged.112 [Kunkel et al., 2008] Storm tracks have shifted northward over the last 50 years as evidenced by a decrease in the frequency of storms in mid-latitude areas of the Northern Hemisphere, while high-latitude activity has increased. There is also evidence of an increase in the intensity of storms in both the mid- and high-latitude areas of the Northern Hemisphere, with greater confidence in the increases occurring in high latitudes.112 [Kunkel et al., 2008] The northward shift is projected to continue, and strong cold season storms are likely to become stronger and more frequent, with greater wind speeds and more extreme wave heights.68 [Gutowski et al, 2008]

The northward shift in storm tracks is reflected in regional changes in the frequency of snowstorms. The South and lower Midwest saw reduced snowstorm frequency during the last century. In contrast, the Northeast and upper Midwest saw increases in snowstorms, although considerable decade-to-decade variations were present in all regions, influenced, for example, by the frequency of El Niño events.112 [Kunkel et al., 2008]

Then we have this apparently as yet unpublished research presented by Dr James Overland of the NOAA/Pacific Marine Environmental Laboratory at the recent International Polar Year Oslo Science Conference (IPY-OSC) where he was chairing “a session on polar climate feedbacks, amplification and teleconnections, including impacts on mid-latitudes.” “Cold and snowy winters will be the rule, rather than the exception,” says Dr James Overland…. Continued rapid loss of sea ice will be an important driver of major change in the world’s climate system in the years to come…. “While the emerging impact of greenhouse gases is an important factor in the changing Arctic, what was not fully recognised until now is that a combination of an unusual warm period due to natural variability, loss of sea ice reflectivity, ocean heat storage and changing wind patterns working together has disrupted the memory and stability of the Arctic climate system, resulting in greater ice loss than earlier climate models predicted,” says Dr Overland. “The exceptional cold and snowy winter of 2009-2010 in Europe, eastern Asia and eastern North America is connected to unique physical processes in the Arctic,” he says.

Even though these storms occurred during warmest winter on record, I think the best way to talk about it until Overland publishes his work is the way NCAR’s Kevin Trenberth did on NPR (audio here): RENEE MONTAGNE, host:  With snow blanketing much of the country, the topic of global warming has become the butt of jokes. Climate skeptics built an igloo in Washington, D.C. during last weeks storm and dedicated it to former Vice President Al Gore, who’s become the public face of climate change. There was also a YouTube video called “12 Inches of Global Warming” that showed snowplows driving through a blizzard.For scientists who study the climate, it’s all a bit much. As NPRs Christopher Joyce reports, they’re trying to dig out. CHRISTOPHER JOYCE: Snowed-in Washington is where much of the political debate over climate change happens. So it did not go unnoticed when a Washington think-tank that advocates climate action had to postpone a climate meeting last week because of inclement weather. That kind of irony isnt lost on climate scientists. Most don’t see a contradiction between a warming world and lots of snow. Heres Kevin Trenberth, a prominent climate scientist at the National Center for Atmospheric Research in Colorado. Mr. KEVIN TRENBERTH (Scientist, National Center for Atmospheric Research): The fact that the oceans are warmer now than they were, say, 30 years ago, means there’s about, on average, 4 percent more water vapor lurking around over the oceans than there was, say, in the 1970s. JOYCE: Warmer water means more water vapor rises up into the air. And what goes up, must come down. Mr. TRENBERTH: So one of the consequences of a warming ocean near a coastline like the East Coast and Washington, D.C., for instance, is that you can get dumped on with more snow, partly as a consequence of global warming. JOYCE: And Trenberth notes that you don’t need very cold temperatures to get big snow. In fact, when the mercury drops too low, it may be too cold to snow. There’s something else fiddling with the weather this year: a strong El Nino. That’s the weather pattern that, every few years, raises itself up out of the western Pacific Ocean and blows east to the Americas. It brings heavy rains and storms to California and the South and Southeast. It also pushes high-altitude jet streams farther south, which brings colder air with them. Trenberth also says El Nino can lock in weather patterns like a meteorological highway, so that storms keep coming down the same track. True, those storms have been big ones – record breakers. But meteorologist Jeff Masters, with the Web site Weather Underground, says it’s average temperatures — not snowfall — that really measure climate change. There’s more water vapor lurking around the oceans, and whatever the proximate cause of any one snow storm, there is little doubt that global warming means the overwhelming majority of East Coast storms will be sweeping in more moisture and dumping it on the ground.

The storms even afflict patrol officers. The DPS spent $3,800 on goggles for officers because of the stinging sand; some reported workplace injuries from irritated contact lenses, said DPS Sgt. Gary Phelps, who has patrolled northern Arizona for most of his 23-year career. "This is a new phenomenon. We have never had these conditions," Phelps said. "As far as visibility, this is the worst I've ever seen. I've been in blowing snow, but I'd take a snowstorm over a dust storm any day. It's awful."

Drivers must sit in 10-mile backups in both directions, the DPS and ADOT report. Many get frustrated and try to make sometimes dangerous U-turns across the freeway median. Some tourists rely on GPS systems to navigate detours. Often, they get stuck in the same brown cloud, lost on an unfamiliar rural road. Some dust storms can be 20 miles wide.

From 2000 through 2008, the state Department of Public Safety logged no dust-related collisions between Milepost 215, east of Flagstaff, and Milepost 260, just east of Winslow. Last year, Highway Patrol cars responded to 11 such accidents, and so far this year, five. Unlike the sudden, short dust storms that strike Interstate 10 south of the Valley, the recent I-40 closures typically last five hours and have dragged on for eight.

ADOT says that, before spring 2009, it had never closed I-40 because of dust storms. At the beginning of that particularly windy season, officials had to close the stretch of interstate between Flagstaff and Winslow because of a bad accident caused by blinding dust. That's when authorities began to close the highway as a precaution. They watched the weather forecast for high winds and sent spotters into the dust to gauge visibility.

From 1997 to 2008, the area recorded winds of more than 35 mph an average 12 times from March through May, Weather Service forecaster Ken Daniel said. Last year, that happened 14 times, and so far this year, 15 times. Winds above 45 mph had occurred an average 1.5 days during those spring months, but last year, they happened six times, and this year, four. "The springs of 2009 and 2010 have been windier than normal, but these winds we have been recently experiencing are not unprecedented," Daniel said.

Theories vary as to why the winds are thick with dust: Historical flooding of the nearby Little Colorado River left a lake bed that steadily dried out into fine sand. The nearby area has been overgrazed. A decade of drought has dried the soil into dust. "It could be global warming, for all I know," said Phelps, of the DPS.

ADOT says I-40 is the most heavily trucked highway in Arizona. Most are taking freight between Los Angeles and the Midwest. "Any time you have to disrupt the schedule of a delivery, it's not just a financial cost, it disrupts the entire supply chain," said Karen Rasmussen, president of the Arizona Trucking Association. "A truck has to arrive within a specific time slot for delivery." If the schedule is missed, manufacturers may have to shut down a plant because they don't have enough inventory. Grocers may not have enough produce, or perishables may start going bad. Trucks usually have return deliveries to make, and those get delayed. Northern Arizona's dust storms have become a national concern for the trucking industry, Rasmussen said.