Extreme weather

KANSAS CITY, Mo. — Those drought-damaged evergreens outside? Regional climatologists say to expect more in the years ahead.

And the surreal mounds of snow now hiding shrubs that barely survived summer’s heat? Get used to that, too.

It seems contradictory, this weird weather whiplash. But just consider the last couple of years in the nation’s midsection. Floods unleashed by record inflows into the Missouri River basin in early 2011. Then sudden and prolonged dryness.

Now 20 to 25 inches of snow heaped on Kansas City in the most dramatic, back-to-back smacking delivered by any winter week that many of us can recall.

Yet to experts who study climate change models, it makes sense.

Think extreme.

Like everything else about the 21st century, Midwest weather in the coming age could be set on sensory overload.

Crispier summers. Fewer but heavier snowfalls. Thunderstorms more intense, bursting between slightly longer arid periods. Crop yields that bounce from boom to bust and back.

“The cutting edge in climate research is in understanding these extremes,” said Bob Oglesby, professor of atmospheric sciences at the University of Nebraska-Lincoln. “The (climate) models suggest we’ll be getting more of them … and now we think we’re beginning to see it in reality.”

No weather event or bizarre season or even stubborn two-year drought proves anything about a warming planet. Even a “superstorm,” the news media’s term for Hurricane Sandy after it dropped from hurricane status, could wind up being a once-in-a-lifetime affair for the New York City region.

That is the hope, of course.

But 2012 was, for America, the overall warmest year ever recorded. And many scientists see the snows that just buried our region as being consistent with long-term climate models that predict more severe swings, and extended periods of extreme, to come.

The latest thinking is partly based on a study published last year in the journal Geophysical Research Letters. It pins “extreme weather events that result from prolonged conditions” on a jet stream that in recent decades has become slower and wavier, with higher ridges and steeper troughs.

Researchers Jennifer A. Francis and Stephen J. Vavrus determined polar warmth melting Arctic ice also was altering the pace and course of west-to-east weather systems around the Northern Hemisphere.

Picture a weather pattern in the belly of a python rather than gliding along a smooth-bending highway. As the jet stream gets loopier, dry spells may stick around longer, the research suggests, and cold blasts may linger. (Just two years ago in Kansas City, at least 3 inches of snow covered the ground for about a month, practically unheard of.)

When a storm system bulges up, it’s apt to barge through this jet stream with pent-up abandon.

Francis and Vavrus noted: “As autumn freeze-up begins, the extra solar energy absorbed during summer in these vast new expanses of open water (from melting sea ice) is released to the atmosphere as heat, thus raising the question of not whether the large-scale atmospheric circulation will be affected, but how?”

In the Plains region and the Midwest — where extreme weather comes with the territory — the question becomes: How extreme can extreme get?

Can we count on more tornado seasons arriving in February rather than March, as the residents of Branson, Mo., and tiny Harveyville, Kan., witnessed last winter? Or will 2013 feel nothing like 2012, which didn’t act much like 2011?

“We could be heading into a period that shows more variability from year to year, or a stretch of a few years being unusual,” said University of Missouri climate scientist Tony Lupo.

Over the long run, “maybe abnormal is normal,” he said.

The nation’s efforts to measure, monitor and possibly predict “extremes” gathered steam in 1995 when an office of the National Oceanic and Atmospheric Administration rolled out the U.S. Climate Extremes Index.

Relying upon data going back to 1910, the goal was to chart historical patterns for very high or very low temperatures, long stretches of drought, one-day bursts of precipitation and the frequency of tropical storms.

All weather out of the ordinary, was diced and bundled annually to show how much of the country suffered one way or another.

To use a football field analogy, the U.S. Climate Extremes Index disregards the middle 80 yards of weather, said Jake Crouch of the NOAA’s National Climatic Data Center: “The values of the 10-yard lines and less, on both sides of the field, are what we’d take into account as being extreme.”

Plotting these extremes through the 20th century, the index reveals a pattern of generally high but jagged activity until the 1940s — when extreme weather appears to take a nap.

It reawakens in the 1950s, then returns to rest until 1980 or thereabouts.

After that, it’s mostly all up. Last year — with fires spreading in the West, drought cracking the heartland and flash floods hitting the Southeastern states — the Climate Extremes Index hit a nationwide record high of 46. That’s 46 percent of the country battling the extremes, more than double the century-long norm.

NOAA furthered its quest to quantify “extreme” and find common causes by commissioning scientists worldwide to analyze disasters of 2011.

They examined intense drought that plagued Texas that year and catastrophic flooding in Thailand. A report last summer determined the global buildup of greenhouse gases made the Texas drought 20 times as likely to happen as in previous decades, but no link was found between man-made warming and rising Thai waters.

You might consider the data wringing a bit tortured — couldn’t extreme conditions just happen?

Weather, in the end, remains fickle and unpredictable. Plenty of meteorologists and other scientists question the purpose of attributing droughts, blizzards and hurricanes to overarching, universal trends.

The website of the Missouri Climate Center has noted above-normal participation for January and pointed out “numerous occasions, both in temperature and precipitation, where Missouri transitioned from one extreme to another in a short period of time.” A dry 1901, for example, became a soggy 1902.

And the link between climate change and hurricanes has been debated since Katrina raged through the Mississippi Delta in 2005.

“If global warming is having any effect on hurricanes, it’s making them less frequent,” said James Taylor, a senior fellow for environmental policy for the Heartland Institute.

The conservative think tank links warming to natural, cyclical causes and denounces claims that man-made carbon dioxide emissions are the culprit.

After all, the New England region devastated by superstorm Sandy has been hit by hurricanes only twice, by NOAA’s count, since the late 1970s — when global temperatures began their rapid climb. By comparison, three hurricanes struck the area in the decade of the 1890s and three more hit between 1954 and 1960.

Climate scientists agree hurricanes indeed could decrease in number over the long haul — as might Midwestern thunderstorms and snow events, for that matter. But when extreme weather does strike, it is likely to hit with more ferocity because of a basic meteorological truth.

“A warmer atmosphere draws more moisture to fall out of the sky,” said University of Kansas researcher Johannes Feddema.

“You can’t say any of these storms are linked to global warming. You can’t. You can only look to a pattern of change over many years.

“Think in terms of a boiling water pot — the bigger the pot, the longer it takes to heat up. We started turning up the stove under a really big pot about 50 years ago, increasing CO2 emissions, and initially we feel little effect.”

Only when the pot gets too hot will we be certain of the effects, he said, and then it will be too late.

Oglesby, the climate scientist in Nebraska, also cautioned against anyone jumping to climate change conclusions from a single “superstorm” in the East or a freaky six days of winter here, even in the midst of a freakier drought.

“In our part of the country, the only thing separating warm currents from the Gulf of Mexico and cold air from the Arctic is a barbed wire fence. It’s easy to have clashing air masses” and constantly shifting extremes, he said.

Still, Kansas State University geographer John A. Harrington said it makes sense to expect a gradual shift toward Kansas City winters bringing heavier snowstorms, if fewer snow events.

Under models of warmer air and swelling seas, “winter storms are juicier,” he said.

Yet away from coastal cities, where much of the research on future threats has been focused, any variety of man-made factors can tweak the long-term climate.

In Kansas, for example, “irrigation has a cooling effect, we know that,” Harrington said.

Urban sprawl, industrialization and deforestation produce warming effects.

“We’ve learned that local people, particularly growers, want to get all the data,” he added. “But they’re hearing mixed messages, and they don’t know who to trust.”

The regional climatologists agree Kansas and Missouri on their own can’t do much to crank down the stove beneath a really big pot.

But planners and policymakers might do some good to avoid assuming any season is apt to be normal.

Their focus from here on should be preparing for and mitigating against disasters, not just reacting when the extremes happen to arrive.

Said Oglesby: “Hope for the best, but expect the worst. Yeah, it’s a cliche. But it’s where we are.”