News

Finding Meaning in Irene

...and playing the odds on odd weather

Comments (10)
Thursday, September 08, 2011
Associated Press Photo
In Vermont, a house founders in flooding caused by Hurricane Irene

By the time Hurricane Irene hit New York City on August 27, climate experts, talk-show hosts, bloggers, politicians, and environmental activists had already staked out their usual positions. Irene was either another sign of human-induced climate change or just another troublesome storm. Or maybe it was impossible to say which it was.

There has been enough weird weather lately to supply combatants in the war over climate change with ample ammunition. Connecticut, for example, saw a record-smashing five feet of snow in the month of January. Tornadoes killed record numbers of people from Missouri to Alabama this spring. An unprecedented plague of intense heat and drought has gripped Texas, Oklahoma, and Kansas for months. Meanwhile, record rainfall and snowmelt in the north-central states swelled the Missouri River with 10 million acre-feet of extra runoff water in July alone.

In the political debate over what’s behind our increasingly unpredictable weather, the standards of logic and evidence tend to be looser than they are in scientific debates. In July 2010, for instance, in the midst of what was to end up being the hottest year on record worldwide, Sen. Jim Inhofe of Oklahoma announced, “We’re in a cycle now that all the scientists agree is going into a cooling period.”

It hasn’t helped that Mother Nature insists on barraging us with mixed messages. This July was the hottest month ever recorded in Oklahoma, while just five months before, some locations in Inhofe’s state had set all-time records for low temperature (-31 degrees F) and snowfall (27 inches in 24 hours).
In 2009, fifteen climate scientists took such fluctuations into account when they concluded in a paper in the Proceedings of the National Academy of Sciences that “it is now more likely than not that human activity has contributed to observed increases in heat waves, intense precipitation events, and the intensity of tropical cyclones.” That statement, based on the most recent report by the Intergovernmental Panel on Climate Change (IPCC), suggests that greenhouse emissions have not only helped barbecue the Great Plains this summer but were a factor in Hurricane Irene’s size and strength as well.

Writer and activist Bill McKibben took a lot of heat from adversaries and a from few allies when he quipped in a recent column that “Irene’s got a middle name, and it’s Global Warming.” But even the tenacious McKibben may be getting tired of having to argue repeatedly, whenever an extreme weather event comes along, that it’s an indicator of human-induced climate change. He ended his article on Irene by noting that this hurricane “will be a distraction in the short run from our efforts, but in the long run it underlines what the fight is all about.”

Roll of the dice

Given the complexity of climate science, it’s not surprising that the best way to get the attention of the media and the public is to talk about wild weather that’s happening right now rather than the bigger threat of long-term climate disruption. But that makes life difficult for those who study climate for a living.

One such researcher is Katharine Hayhoe, an associate professor at Texas Tech University. She sees a clear necessity to come back hard against fatuous arguments that, she says, go something like this: “Well, you know, temperatures are cooling in the month of September in Erie, Pennsylvania, so how can the planet be warming?” But, she warns, climate scientists have to be careful themselves not to go beyond the data: “It is very tempting to seize on a single dramatic event, but we have to stay true to what we know, to stick to terms like ‘consistent with’ and ‘risk of...”

In public statements, most climate scientists are indeed careful to stress that we cannot draw conclusions from individual extreme weather events. But Michael Mann, director of the Earth System Science Center at Pennsylvania State University, is now thinking that such caution may have gone too far.
He says many of his colleagues, weary of being attacked by climate skeptics, tend to “jump too soon”, starting their responses to reporters by discounting the relevance of individual weather events. But by understating the links, he believes, they are “erring in the opposite direction”, which in itself can be misleading. “Statistics show very much that these events really are part of bigger trends,” he stresses.

To illustrate, Mann uses a metaphor popular among climate researchers these days: “Suppose you’re betting on dice, but that someone had replaced the ‘five’ on this particular die with a second ‘six’. If you don’t know this, you might get cheated out of a lot of money. But when you demand your money back, can you point to any one roll of that die that you can prove lost you money? No, you can’t.” But, he says, it’s a fact that the size of your losses is a direct result of the change in the die.

Similarly with the Earth’s atmosphere, he says, statistics tell us that shifts in climate have contributed to extreme weather: “As the numbers start piling up, you can say that they have been shifted by climate change. A thousand-year event becomes a thirty-year event.”

Daily weather data that have been recorded for fifty or a hundred or more years in many places can tell us a lot about extremes. Says Mann, “If we were seeing a lot of longer, more intense cold periods, we’d all be scratching our heads. But when you confirm what the hypothesis proposed, you have an increased degree of confidence.”

(Mann’s confidence that we are seeing a real impact from greenhouse emissions has made him a popular target for climate skeptics. In 2009, email hackers charged that he had engaged in scientific misconduct; however, repeated inquiries, including two by his university and a more recent one by the National Science Foundation, cleared him of any wrongdoing. Meanwhile, conservative Virginia Attorney General Kenneth Cuccinelli’s search for evidence that could be used to prosecute Mann has turned up nothing.)

But if climate models project with some assurance that present and future emissions of greenhouse gases will lead to rapid warming of the atmosphere and more extreme weather, is it even necessary to continue digging into past climate and weather records for evidence of change? Do historical studies add any useful information as we plan for the future?

A 2008 report published by the U.S. Climate Change Science Program stressed that while the past does not hold all the answers, it is important to learn what history can tell us. The first step, they explain, is “detection”—establishing that changes have occurred in some type of extreme, say heat waves, over time.

Then comes the second step, “attribution”, in which those observed changes are compared with changes that would have been predicted by climate models. If real-world weather events are consistent with events that are expected to occur in a greenhouse world but not in a world of exclusively natural forces, that is evidence for a human impact on extreme weather.

When extreme heat becomes routine

If the brain-cooking heat that gripped much of the country these past two summers has seemed to be unusually persistent, it’s not just our fevered imaginations. Weather records show that multiple-day runs of exceptionally high temperatures have become more common since 1960. A half-century ago, record high and record low temperatures occurred at approximately the same rate in the United States. Now record highs are happening at least twice as often as record lows, and the ratio might be as high as four-to-one.

One link between heat waves and human-induced warming of the atmosphere is simply a matter of statistics. Daily temperatures are distributed like most phenomena, in a bell-shaped curve, with most readings heaped up in the middle—that is, near the average for the date—and the rarer extremes tapering away in both directions as “tails”. As the earth warms, that curve tends to shift to the right, toward higher temperatures, with its right tail leading the way.

Even if the bell curve stays exactly the same shape as it moves, a small shift can lead to many more heat waves. Notes Michael Mann, “The one-degree Celsius increase we have seen in average temperature, for example, appears to be leading to a doubling of the rate at which record-breaking temperatures occur.” That happens because as the curve moves right (a phenomenon firmly linked to greenhouse emissions), the “fatter” part of the tail moves into “extreme” territory.

But there may be more to the story. The monster heat wave that killed tens of thousands of Europeans in 2003 was off the charts—impossible to explain by a simple shift in the bell curve, according to a Swiss climate team. The group reported a few months after the disaster that even considering the increase in average temperatures in Europe from 1990 to 2003--but assuming no change in the shape of the curve—a heat wave like that of 2003 could be expected to occur only once every 46,000 years.

The fact that the 2003 event actually happened led the group to search for other explanations in greenhouse climate models. Those models, they discovered, predict a large increase not only in average temperature but in variability as well—a flattening of the bell curve that would make killer heat waves much more common in, say, Switzerland.

Indeed, the Swiss scientists’ models suggest that in Central Europe “towards the end of the century—under the given scenario assumptions—about every second summer could be as warm or warmer (and as dry or drier) than 2003.” And while not as wildly unpredictable as Europe ‘03, the 2010 killer heat wave in Russia went well beyond anything else yet experienced and might also be an indicator of a flattening bell curve.

“The heat in Russia and the floods in Pakistan in the past year were not just weather flukes,” adds Mann. Greenhouse models, he points out, projected that sinking dry air would migrate from northern Africa and southern Europe toward Central Europe and Russia in summer, and that moist air would move north from the tropical Indian Ocean toward subtropical Pakistan. “Those events were part of a larger circulation pattern,” he says—a pattern that greenhouse-climate models had predicted.

Extreme rains, deep snow

In recent years, precipitation patterns appear to have gone haywire, not just in Pakistan but on every continent. Katharine Hayhoe has seen this up close: “In the five years I’ve lived in West Texas, we’ve had a 111-day rainless stretch—the longest ever recorded—and two ‘hundred year’ rainfalls”—ones so heavy that such an event occurs only once per century on average.

“But,” she says, “it all makes sense from a basic physics perspective. The atmosphere is holding more water vapor. Storm systems, when they come, have more to work with.”

Warmer air is capable of holding more water vapor than is cooler air. As a consequence, the concentration of moisture in the atmosphere also has been increasing since the 1960s, both in the United States and across the globe. A comprehensive 2007 study led by scientists at Yale University concluded that the increases in humidity observed planet-wide can be attributed to human influence and that natural forces alone cannot explain the change.

With more moisture in the air, an increasing proportion of precipitation is coming in the form of more intense rainstorms around the world. Over the past thirty years, the southeastern United States has seen simultaneous increases in droughts, wet years, and strong rainstorms. According to a 2010 report by researchers at the National Oceanic and Atmospheric Administration’s Climate Prediction Center in Maryland, the University of Texas, and Duke University, these big swings in precipitation are related to the continuing rise in Atlantic Ocean surface temperatures and the increasing variability of those temperatures.

Even on a warming planet, regions with traditionally cold winters will still have plenty of below-freezing weather; when that cold air combines with moist air masses (in a generally warmer atmosphere that’s able to carry more water vapor than it used to), a lot of moisture can suddenly be dumped in the form of snow. There has been a slight upward trend in strong snowstorms over the past century in the United States. What part of that trend you see depends on where you live. Warmer areas of the country are seeing fewer big snowstorms, but the upper Midwest and the Northeast are getting hit with more of them.

A June 2009 report published by the U.S. Global Change Research Program found that the share of precipitation falling as snow rather than rain is increasing in the northeastern United States. Furthermore, said the report, “Heavy snowfall and snowstorm frequency have increased in many northern parts of the United States.” Six months after publication of that report, with the northern and middle Atlantic coast paralyzed by record snowfall, the authors could be even more confident that the trend they had observed was not a mirage.

And as we have seen once again, those most media-friendly of all extreme weather phenomena—hurricanes—are also among the most controversial subjects in the climate debate. A group of experts published a paper last year in Nature Geoscience examining all existing evidence of links between greenhouse emissions and Atlantic hurricanes. In contrast to the IPCC report that had concluded it is “more likely than not” that humanity’s emissions have influenced tropical cyclone activity, this study found that “despite some suggestive observational studies, we cannot at this time conclusively identify” a human fingerprint on the increasing intensity of tropical cyclones. However, the group concluded, “a substantial human influence on future tropical cyclone activity cannot be ruled out.”

No news is bad news

Whatever happens on the ground, in the sea, and in the atmosphere in coming decades, it is very likely that public discussion of the climate will tend to focus on events like heat waves, floods and storms more than on the invisible, and ultimately more important, transformation of the planet-wide climate.

In a 2007 essay, Andrew Revkin of the New York Times explained why storms make headlines but climatic disruption does “not constitute news as we know it.” He predicted that “the incremental nature of climate research and its uncertain scenarios will continue to make the issue of global warming incompatible with the news process. Indeed, global warming remains the antithesis of what is traditionally defined as news... Journalism craves the concrete, the known, the here and now and is repelled by conditionality, distance, and the future.”

But could it be that energetic public discussion of meteorological media events like Irene can actually help remedy the situation, by introducing more people to the complex forces that are taking our climate on this wild ride? Do more people now know, for example, that if there is extraordinary weather again this winter, it can be entirely consistent with what we’d expect when living in a warmer, moister atmosphere? Will more of us see in next summer’s heat waves and hurricanes the roll of loaded dice?

When I asked Michael Mann those questions, he chuckled. “Well, yes, I hope the past year has provided a learning opportunity” for Americans. But will we actually learn from it? On that question, Mann—who makes his living estimating statistical confidence—did not seem very confident at all.

Comments (10)
Post a Comment

I do believe the recent severe weather is caused by Global Warming. Republicans will have you believe it is all non sense of course. The Republicans really don't care either way, they never do, they hate living things and nature and are bent on destroying everything that resembles progress. Even though it is true and it is devastating to entire states and to the entire planet, Republicans will just argue it's not, to disagree with Democrats, because that is all Republicans know how to do, be ignorant of the facts and argue with people smarter than they are.

Posted by Global Warming is Real on 9.7.11 at 14:04

Wow, and not one mention of HAARP. Glad to see you're giving the people all the facts.

Posted by CSinPA on 9.7.11 at 14:12

What a blithering idiot! People like you are the biggest problem out there. You blame a group of people because there conservative viewpoint. The fact is is that you are not smart enough to argue on merit and have to resort to attacks by calling half of America stupid. And why is it that if "Democrats" are so much more smarter that they only preach about "progress" but don't practice it.

Posted by mike vick on 9.7.11 at 14:34

I love the outdoors and all living things. as this planet, and it is consistantly changing just as it has since the start of time.and what progress can the states do? when it is just us? oh i know throw money at it. thats what the dem. wits do. thats progress...why dont all of the good doers help out and git all the other countrys to take steps back with us and shut the plant down industraly and we all die from lack of the basics.....after all people shouldn't be here right? and the fact is if you think its all because of us, you are ignorant as the others.....

Posted by james the mountain ma on 9.7.11 at 14:39

This was a very informative and well written article. I learned a lot. Atta Boy, Stan.

Thanks to the comments, I can relax in the knowledge that Global Warming, El Nino & La Nina are not the influences contributing to the recent weather extremes and that it is just the Republicans going about their business of "hating living things and nature and destroying everything that resembles progress". I didn't realize that they had so much control over the weather. I guess I better vote for them more often.

Posted by Feenix6 on 9.7.11 at 14:48

This article is fairly even handed as it points out that really, we don't have a clue what causes weather patterns. What is disturbing to me is that the "science" of global warming is being regulated by those who are emotionally and financially involved. You cannot get a government research grant these days in any field without it trying to alleviate or prove the existence of global warming. This means the only scientists that get funding are the ones who are emotionally attached to this project.

Other than the stated, I have two very significant issues with the "global warming" problem. First, the name keeps on changing. First it was global warming, and now global climate change, and soon it will be something else. Along with this it seems that the scientists are basing proving their hypotheses on existing data rather than having to prove their hypotheses on coming data. In other words when something happens that does not support "warming" they find some other explanation of what happened. Case and point is the last decade where our global average temperature remained unchanged. After this occurance the scientific community has started to try to blame this on sulfur in coal and el nino weather patterns. These kinds of inputs were not in their weather models?

Second, if the theory is correct that we are drastically changing the earth's climate by burning coal and oil what are we to do? I have seen no solutions other than shutting things completely down. No matter how much you try to back solar and wind it will never replace coal and oil. If we were serious about this we would have to shut it all down, thus killing billions around the world. If we are to survive under such circumstances, we must find a different way to convert sunlight/heat into storable energy. Such a method does not currently exist.

I also feel that the environmentalists have done us all a great disservice especially if they are right on global warming. They have been so fanatical as to destroy any relation with reasonable people. They have burned bridges, they have blown data out of proportion, and thus many have not believed. Al Gore is among the worst at this because his film was so poorly backed with science that it was a joke. Should it have been educational at all it may have helped him rather than hindered him.

Posted by Bryce on 9.7.11 at 14:49

Cold weather and heavy rain is proof of manmade global warming. Warm weather and a lack of rain is proof of global warming. Deep snow fall is proof of manmade global warming. Lack of snowfall is proof of manmade global warming. Cooler than normal temperatures is proof of manmade global warming. Hotter than normal temperatures is a proof or manmade global warming. High hurricane and tornado activity is proof of manmade global warming. A lack of hurricane and tornado activity is proof of manmade global warming...

Exactly what weather pattern or phenomenon would be considered a sign that man made global warming does not exist?

Posted by mljacobson on 9.7.11 at 15:20

How do you explain the "global Warming" following the Ice Age??

Posted by sandooch on 9.7.11 at 15:40

Dear World,

Carbon Dioxide is a greenhouse gas known to trap heat. This is and always has been a matter of elementary and basic scientific fact akin to gravity or electricity or magnetism or really, any of the basic scientific truths that power our modern world. The CO2 levels in Earth's atmosphere have been on a dramatic rise over the last century. Also, a well documented and indisputable scientific fact. Quite frankly, there is no other way to explain the increases in average temperatures and their overall affect on extreme weather. Science is neither magic nor dogma that one has the luxury of choosing to believe it. Science is wholly based on observation. Anthropomorphic climate change is an observaton. It's as simple as that. The deniers never seem to bother or care about what will happen if we fail to do nothing. We only have one planet, best we not leave its fate up to a roll of the dice... call me crazy.

Yours,

Rational

Posted by Rational on 9.7.11 at 16:04

Dear Rational,

The things you say are true. CO2 is a greenhouse gas. Humans are dumping large quantities into the air. What we don't know and probably never will is if the affect of the human generated carbon affects the weather like a mouse turd affects the weight of an elephant or if it has a more significant impact.

We also know this about the debate. Large amounts of money are involved on both sides and so it is hard to know who is telling the truth.

Please consider the following: As a political tool controlling carbon emissions can control almost any industry there is. In other words the government can grant permits to some companies (quid-pro-quo) to burn carbon while denying others based on agendas. This seems like a rather convenient tool to use that is universal world wide.

If you read my previous post you can read about my skepticism of global warming and even the scientists who are doing the research on it. It is far from being a fact that the CO2 in the air that we create has any noticable affect on our weather. There are other avenues that seem to fit better than CO2 sucha s cosmic rays and sun spots. This is science too, but is being ignored, I believe, because the CO2 control is so much more valuable to politicians.

Posted by Bryce on 9.7.11 at 16:51
Comment:

Name:

Password:

New User/Guest?

Find it Here:
keyword:
search type:
search in:

« Previous   |   Next »
Print Email RSS feed


In Satoshi We Trust?
Outside the Cage
How solid is the case for organic and cage-free egg production?
Between the Lines: Practically Organic
Does the organic farming movement make perfect the enemy of good?
Scene Here: The Kitchen Garden Farm
From Our Readers
Profiles in Survival
Young business owners in retail-rich Northampton get along by getting along.
The Burning Question
Neighbors of a proposed wood-burning plant in Springfield cry foul air