OK, here’s something I don’t get: a new paper in GRL by Russell Vose at the National Climatic Data Center suggesting the decrease in the diurnal temperature range slowed dramatically from 1979-2004. Maybe some of you climate types can ‘splain this?

(Backstory for non-climate wonks: The “diurnal temperature range” is the difference between the daytime high and nighttime low. My understanding, based on Karoly et al. in 2003 in Science, was that greenhouse warming would be expected to reduce the DTR by disproportionately increasing the overnight low temperatures. That’s exactly what I see happening in my own little corner of the world, with overnight lows warming a lot more than daytime highs. In other words, DTR is part of my day-to-day experience of global warming. It means my morning bike rides are a bit more comfy.)

Kevin Vranes on the reality of Kyoto and Montreal:

The real consensus we need to reach here is whether slowing GHG increases is worth it or not. Kyoto has always been close to irrelevant climatologically and while I feel the pain of those making the “it’s a start, a necessary first step” argument, I have never been too sympathetic to it. Does it make a difference whether we forestall achieving 2xCO2 by a decade or two? It may be a depressing answer to some, but my answer is, “I doubt it.”

Reading John Houghton’s Global Warming: The Complete Briefing this evening, I was reminded of one of my favorite episodes in the history of science: Lewis Fry Richardson and the first numerical weather forecast.

Richardson was of that era that ended with the burst of modernism in the early 20th century – a generalist, dabbler in many things. A pacifist, he was working as an ambulance driver in World War I when he envisioned the calculations necessary to forecast the weather. “With much painstaking calculation with his slide-rule,” Houghton writes, “he solved the appropriate equations and produced a six-hour forecast.” The problem, as Houghton notes, was that it took him six months of work, which doesn’t really meet the timeliness requirements of a usable forecast. (He also seems to have gotten it wrong, I’m told, not understanding the importance of the relationship in his model of grid size to time step.)

But the coolest part is the solution he envisioned to get a forecast done in a reasonable time. Houghton again:

To apply his methods to real forecasts, Richardson imagined the possibility of a very large concert hall filled with people, each person carrying out part of the calculation, so that the integration of the numerical model could keep up with the weather.

I riffed on this last year in a story about the new Red Storm supercomputer (sub. req.), which uses an architecture conceptually quite similar to Richardson’s.

Richardson just wanted a way to forecast the weather, and he could not possibly have imagined much of the computer technology at Red Storm’s heart.

But the basic concepts he envisioned— a way for many calculations to swiftly be shared and integrated into a useful whole— lie at the heart of the machine to be built at Sandia.

Cray Inc. is building the $90 million Red Storm for Sandia’s nuclear weapons work. It will use 11,648 computer chips identical to the ones that power desktop computers.

The chips will be tied together in an architecture that bears a striking resemblance to Richardson’s idea.

“The guy was so far ahead of his time,” said Dave Gutzler, a University of New Mexico climate researcher and aficionado of Richardson’s work. “Almost nobody understood the significance of what he was doing.”

Forests are a good thing, right? And reversing deforestation is a smart approach to climate change – locking all that carbon back up in trees, right?

A new paper out of Lawrence Livermore throws an odd monkey wrench into the conventional wisdom, using model simulations to conclude that grassland cools while forest warms:

We find that global replacement of current vegetation by trees would lead to a global mean warming of 1.3°C, nearly 60 percent of the warming produced under a doubled CO2 concentration, while replacement by grasslands would result in a cooling of 0.4°C. It has been previously shown that boreal forestation can lead to warming; our simulations indicate that mid-latitude forestation also could lead to warming. These results suggest that more research is necessary before forest carbon storage should be deployed as a mitigation strategy for global warming.

Interesting work presented at AGU by a University of Alabama/NASA/etc. group suggesting the the possibility that Mayan deforestation may have brought on the drought conditions that some blame for the collapse of classic Maya culture.

I have thought that the Maya might make a good case study for a society done in by drought, expanding in wet times and therefore losing the resilience necessary to cope with drought. Smart archaeologists disagree on the drought hypothesis, with some arguing that “collapse” was not synchronous across the Maya region and therefore drought is not a reasonable explanation. But it’s at the very least an idea worth entertaining.

This new work suggests an intriguing wild card. What if cutting down the rainforest reduced the amount of atmsopheric moisture available via evapotranspiration, thereby reducing rainfall? The group’s modelling run suggests it’s a possibility:

Domain averaged dry season rainfall in the Maya lowlands decreases to 128.9mm for the deforested scenario, a decrease in 9.7 percet over current conditions…. Continued deforestation that would be representative of those prior to the collapse of the Maya civilization in the region can be expected to lead to additional decreases in dry season precipitation throughout the entire region by about 10mm to 100mm. Improper land use management in this region could lead to futures catastrophes for the modern humans.

(Hat tip Roger Pielke Sr., who is one of the coauthors and who pointed this out to me.)

Jeff Bingaman, fresh from Montreal, talks about U.S. greenhouse gas policies:

Sen. Jeff Bingaman, D-N.M., thinks now is the time for the United States to act on climate change.

But Bingaman, who has emerged as a congressional leader on the issue, acknowledges he has his work cut out for him in persuading the Bush administration.

That was the reality Bingaman faced last week as he stepped to the lectern as the keynote speaker at an international gathering of legislators in Montreal.

Individual state and local governments, along with many in U.S. industry, are pushing for U.S. leadership in curbing greenhouse gas emissions, Bingaman told the audience, according to a text of his talk. But the Bush administration does not agree.

The Bush administration opposes participation in the international community’s mandatory emissions caps, saying it would harm the U.S. economy while exempting developing nations like China and India.

“The truth is,” Bingaman told the gathering, “there is a diverging view within the United States that I do not believe is accurately represented by the president and the current administration.”