The question is trickier than it sounds, because in addition to being a noisy bit of the Climate Wars argy-bargy, it's a big source of uncertainty for policy makers trying to understand what sort of adaption will be required and what sort of mitigation should be undertaken.

The problem is that there's actually precious little data about how bad it really might be - where might crops whither and where might they prosper, and what's the net difference? Where might water supplies dwindle, and where might they increase?

This afternoon in Science Express, a team led by Dagmar Schröter at the Potsdam Institute for Climate Impact Research published a serious and useful look at the question for Europe, matching up climate models with economic scenarious to try to get a clearer picture of impacts over the next century. Especially significant was what they called "water stress," with lots of people living in places that in the future may not have enough water to support them the way they live today. Cropland declines significantly, and forest fires go up:

Among all European regions, the Mediterranean appeared most vulnerable to global change. Multiple potential impacts were projected, related primarily to increased temperatures and reduced precipitation. The impacts included water shortages, increased risk of forest fires, northward shifts in the distribution of typical tree species, and losses of agricultural potential. Mountain regions also seemed vulnerable because of a rise in the elevation of snow cover and altered river runoff regimes.

The statistical questions raised by MM are somewhat arcane for the general blog-reading audience. In the first case, MM argued that the methodology used by Mann et al. essentially produces "hockey sticks" artificially out of random noise. Von Storch (who one of the M's loves to quote approvingly, and who is one of the deans of climate statistics) disputes this assertion. Huybers argues that MM's criticism of the Mann et al. choice of statistical significance tests is wrong. Suffice it to say, for purposes of the policy discussion in which MM have been invoked, that the responses by von Storch and Huybers suggest that the MM statistical criticisms of the hockey stick reconstruction are not as bone-headedly obvious as Michael Crichton wants to believe.

Pielke's contention is that, while surface temperature data may support the claim, the surface thermometer record "is not ... the most appropriate metric to evaluate global warming." And from a climatological view, of course, he is absolutely correct. Various layers of the atmosphere behave quite differently, and a complete picture requires looking at all of them, which, as Pielke notes, paint a much more complex picture of warming than a simple "warmest ever" headline.

Pielke also gives an important nod to regional anomalies, which he rightly argues "are what we should be focusing on in terms of long-term climate trends, rather than surface globally-averaged temperature trends."

But this is a newspaper story for a national audience, where you really get to say one clear thing that has to communicate with people everywhere. If it were for a regional audience (like, say, mine) it could focus on a regional anomaly. But whoever is going to be reading this is living on the planet's surface, so that's the temperature number that's going to matter to them.

Keep that in mind as I'm fascinated by climate and weather extremes, so this from this morning's NHC discussion of hurricane Wilma caught my eye. (The old record was Gilbert in 1988 at 888 mb. Wilma's unofficially at 881 - 884. This like golf - lower pressure equals more powerful hurricane.):

AN AIR FORCE RECONNAISSANCE PLANE MEASURED 168 KNOTS AT 700 MB AND ESTIMATED A MINIMUM PRESSURE OF 884 MB EXTRAPOLATED FROM 700MB. UNOFFICIALLY...THE METEOROLOGIST ON BOARD THE PLANE RELAYED AN EXTRAPOLATED 881 MB PRESSURE AND MEASURED 884 MB WITH A DROPSONDE. THIS IS ALL IN ASSOCIATION WITH A VERY SMALL EYE THAT HAS BEEN OSCILLATING BETWEEN 2 AND 4 N MI DURING EYE PENETRATIONS. THIS IS PROBABLY THE LOWEST MINIMUM PRESSURE EVER OBSERVED IN THE ATLANTIC BASIN AND IS FOLLOWED BY THE 888 MB MINIMUM PRESSURE ASSOCIATED WITH HURRICANE GILBERT IN 1988. HOWEVER...ONE MUST BE VERY CAREFUL BEFORE IT IS DECLARED A RECORD MINIMUM PRESSURE UNTIL A FULL AND DETAILED CALIBRATION OF THE INSTRUMENTS AND CALCULATIONS IS
PERFORMED. SO PLEASE DO NOT JUMP INTO CONCLUSIONS YET...BE PATIENT.

]]> http://www.inkstain.net/fleck/archives/001944.html climate variability John Fleck 2005-10-19T08:55:12-07:00 Before I slipped away for vacation last week, I was able to write this (sub. req.):

New Mexico's massive piñon die-off of 2002 and 2003 might be a harbinger of life here in a warming world, new research suggests.

High elevation forests that had survived previous droughts saw as much as 90 percent piñon mortality, a team of researchers led by University of Arizona ecologist Dave Breshears reported Monday in the Proceedings of the National Academy of Sciences.

"Across a whole landscape, this system got whacked," Breshears said in a telephone interview.

Drought weakened the trees enough that bark beetles could kill them, but warmer temperatures appear to have played a key role, the scientists found.

The temperature difference— 1 to 2 degrees Fahrenheit above the long-term average— might not sound like much. But the scientists say it made the difference, leading to tree death in areas relatively unaffected by the drier drought of the 1950s.

"This is a different kind of response than we saw following the 1950s drought," said Breshears, who has been studying piñon woodlands since the 1980s. "This drought was hotter."

Breshears, in an interview, was careful not to blame the 2002 die-off on human-caused global warming, saying no one event can be unequivocally linked to the planet's long-term rising temperature trend.

But he said the dramatic drought-induced changes in the Southwest's landscape since the turn of the 21st century are consistent with global climate change projections.

"We're more likely to get more frequent, more intense droughts," Breshears said.

For those of you not in the U.S. southwest, the piñon/juniper woodland is a dominant middle-elevation forest type that was decimated a few years back - whole hillsides turned from their usual green to a frightening greyish brown. Like dwindling snowpacks, it's a warming effect that you can see on the ground, now, but until Breshears et al. did this work, no one had established the link. It's still a controversial link, as the comments from Julio Betancourt in my story suggest. (Betancourt, a terrific scientist who I respect on these issues and who probably knows the drought of the 1950s better than anyone, believes we don't enough about 50's dieoff to be sure the current dieoff is worse.) But caveats notwithstanding, it's nevertheless important work of the sort that matters - climate science helping us understand impacts on the ground.

]]> http://www.inkstain.net/fleck/archives/001942.html climate variability John Fleck 2005-10-18T09:21:04-07:00 Michael Mann was in town speaking at the University of New Mexico yesterday. I wrote about his talk (sub. req., lots of quotes from the story below the fold) and got to spend some useful time talking to him about big picture climate issues. (Thanks, Mike!)

I didn't have much space, so the story was short, and I chose to focus more on regional climate issues than hockey sticks. I'm kinda sick of hockey sticks, and it was interesting to see that Mann's recent work, the stuff he chose to talk about in his UNM talk and the stuff I've been reading recently, is moving beyond the stick in ways that I think are incredibly useful.

(click through for more)

Read more...

]]> http://www.inkstain.net/fleck/archives/001937.html climate variability John Fleck 2005-10-08T12:19:18-07:00 I spent a mesmerizing couple of hours yesterday afternoon with the diaries of John D. Lee.

The only place I could find it was in the Albuquerque special collections library, a lovely old building that used to be the city's main library and now houses the rare stuff they won't let you check out.

(click through for more on Lee)

Read more...

]]> http://www.inkstain.net/fleck/archives/001932.html climate variability John Fleck 2005-10-02T09:18:26-07:00 I got a nice note this morning from Luboš Motl about yesterday's post, quoted in its entirety here (with Dr. Motl's kind permission):

Dear Mr. Fleck,

I think that you're being outrageously unfair to me. Everyone who follows this debate knows that I understand those climate issues that have been discussed at least as well as William Connolley does. At least, unlike him, I know what the latent heat of ice is - while he believes it is 1000 times smaller than it actually is.

Therefore it is highly annoying that you call this semi-educated guy a "British climate researcher" while your sentences about me are constructed in such a way to indicate that my opinion does not matter so much. It's just unfair in the case that you realize that what you write is nonsense. If you don't realize it, then it may be that you are honest - but in that case your intelligence is probably not too high.

You also accuse me that I don't realize that there are stupid people on all sides. I have no idea why you think that I don't realize it. It's just another lie - another completely unjustifiable accusation. For example, the creationists may be on my side politically, but they don't have a scientific approach to biology. If you mean Crichton, you would have to give more details. Crichton's speech was spot on and it was extremely intelligent. You have not found anything wrong with the speech either.

You're just apparently used to the fact that you can write a few kilobytes of lies and false accusations, without any justification whatsoever, and there are always sufficiently many stupid and politically biased readers who will appreciate your acts nevertheless.

I believe that you should apologize to me for this outrageous text.

Thanks for your understanding
Lubos

]]> http://www.inkstain.net/fleck/archives/001931.html climate variability John Fleck 2005-10-02T09:05:10-07:00 I've been reading about Lee's Ferry, and puzzling over the different ways to refer to it. It's the spot on the Colorado River just downstream from Glen Canyon Dam that today is the put-in for Grand Canyon river trips. It used to be the only reasonable river crossing for hundreds of miles in either direction, a ferry crossing set up by old John D. Lee back in the 1870s. It also is marks the line between upper and lower basin states for the purpose of division of Colorado River water.

My confusion: on maps and in books it's alternatively "Lee's Ferry" or "Lees Ferry" or "Lee Ferry." Found an answer of sorts this weekend in "A Crossing on the Colorado: Lee's Ferry" by Evelyn Brack Measeles:

The name was officially declared to be Lees Feery (no apostrophe) in the Sixth Report of the United States Geographic Board.*

* Rusho, W.L. "Living History at Lees Ferry," Journal of the West, Vol. VII, No. 1, Jan. 1968

So it's officially "Lees Ferry," but Measeles doesn't like it. "His has always been the pervading presence," she writes, "no matter how many other people touched it." So she give's it the posessive. I agree.

]]> http://www.inkstain.net/fleck/archives/001920.html climate variability John Fleck 2005-09-25T19:49:59-07:00 I'm working on a quantum physics story at work, which means a great deal of procrastination, as anyone who's tried to write about quantum stuff for a lay audience can I'm sure understand. My latest way to waste some time while creating the illusion of doing useful work: Climate Change in the West.

]]> http://www.inkstain.net/fleck/archives/001916.html climate variability John Fleck 2005-09-22T12:00:10-07:00 Charles Darwin, meteorologist

]]> http://www.inkstain.net/fleck/archives/001915.html climate variability John Fleck 2005-09-21T21:02:00-07:00 A thoughtful reader points out, in regard to last night's post about climate variability in the Colorado River basin, that I didn't make what I will call the Pielke Jr. point: "the problem is not the climate change but the societal changes!" (That's quoting my thoughtful reader (TR), not Pielke.)

TR is of course right. It's not climate variability per se that is the problem here. The problem is twofold. First, it's a problem that the folks who set up the system for allocation of Colorado River water didn't understand the extremes of variability that could affect the river's supplies. The second is that population and associated human systems have grown up around the Colorado River's water with no clear understanding of the variability in water availability that is inevitable in the long run. We are, as a result, extremely vulnerable to the sort of severe, sustained drought that tree ring records suggest has happend in the not-so-distant past. We're not vulnerable in the same way as the Anasazi. We son't starve. But there could be significant societal dislocations.

One thing worth doing in this context is is to examine the difference between the hunter-gatherers who inhabited the Four Corners region before the puebloans, as compared to the Anasazi. Hunter-gatherers survived droughts worse than the ones that coincide with the end of the Anasazi culture. The short answer for why is that the hunter-gatherers had apparently read Pielke, and therefore did not max out the resources, leaving them the flexibility to respond to drought when it happened. In other words, they reduced their societal vulnerability to climate variability.

The Anasazi did not read Pielke, and died.

]]> http://www.inkstain.net/fleck/archives/001910.html climate variability John Fleck 2005-09-19T21:13:38-07:00 This is Delph Carpenter, speaking Nov. 12, 1922, ad the twelfth meeting of the Colorado River Commission:

The hydrographers and experts advise me that a twenty-year record on a river is adequate in its completeness and includes enough years to warrant an assumption that the average there deduced would be the average flow of the river in the future.

How wrong he was.

The green dots represent the Colorado River's flow at Lee's Ferry (adjusted to represent the flow if the river would have been undammed). The black line is the amount the commission assumed based on the available river data - about 20 years' worth. The blue line is the actual long-term average since 1896. And the red jiggly line is the rolling 20-year average, positioned at the end of the 20 year interval. You can see it's highest in the early 1920s - at about the time the commission was meeting in Santa Fe. (data from the Upper Colorado River Commission)

Carpenter and the other commissioners thought that a sufficiently long period - perhaps ten years, but certainly twenty - should be sufficient to average out the ups and downs of long-term climate cycles in the west. You can see they were quite wrong.

]]> http://www.inkstain.net/fleck/archives/001909.html climate variability John Fleck 2005-09-18T21:08:32-07:00 So the Sahel, where people really die when drought happens, could be wetter in a globally warmed world, according to new research by a team led by Reindert J. Haarsma of the Royal Netherlands Meteorological Institute:

We hypothesize that through this mechanism greenhouse warming will cause an increase in Sahel rainfall, because the warming is expected to be more prominent over the summer continents than over the oceans. This has been confirmed using an ensemble of 62 coupled model runs forced with a business as usual scenario. The ensemble mean increase in Sahel rainfall between 1980 and 2080 is about 1–2 mm day−1 (25–50 percent) during July–September, thereby strongly reducing the probability of prolonged droughts.

Published in GRL Sept. 10.

]]> http://www.inkstain.net/fleck/archives/001900.html climate variability John Fleck 2005-09-12T08:01:46-07:00