global warming for dummies

I think the author is getting a little melodramatic to say it's a "full-court press" to prove that AGW has something to do with the tornadoes. Trenberth's comments are being misconstrued to look like he's directly blaming AGW for weather events, when in fact he means much more subtle, indirect effects.

NBC News anchor Brian Williams couldn’t contain himself trying to get Weather Channel meteorologist Greg Forbes to say people caused the strong tornadoes via global warming.

Another fine example of our crappy media trying to go for that extreme view, scare people into viewing for ratings, and distort the reality in the process.

The liberal advocacy group Center for American Progress, in an article titled “Storms kill 250 Americans in states represented by climate pollution deniers,” asserted that all weather events are affected by global warming. This is just a small sampling of the alarmist call to arms in the wake of last week’s tornadoes.

Notice that there's no mention of by what magnitude that all weather events are affected by global warming...

http://www.realclimate.org/index.php/ar ... -may-2011/

My question to RC is about the extreme number of extreme events in a short time – i.e the statistics of weather, i.e climate. It’s not just one big flood, it’s the concentration of big floods in a short time. RC climatologists, why do you maintain radio silence on an aspect of climate change that is of great public interest?

[Response: It's not an easy topic and there also hasn't been a whole lot of research on it. You have to have several types of information that we don't necessarily have, like a dependable observational record that goes back as far as possible, and good physical models that connect the different, relevant spatio-temporal scales. Here's one paper that lays out some of the problems and a proposed approach to the topic, w.r.t tornado analysis: Van Klooster and Roebber, 2009: Surface-Based Convective Potential in the Contiguous United States in a Business-as-Usual Future Climate. J. Climate, 22, 3317–3330. Here's another: Trapp, Halvorson, and Diffenbaugh (2007). Telescoping, multimodel approaches to evaluate extreme convective weather under future climates, J. Geophys. Res., doi:10.1029/2006JD008345.--Jim]

Wallace Broecker in Fixing Climate suggests that La Nina’s will become stronger and more frequent. He is honest though and says that it isn’t yet clear.

It is a complicated picture so I'll only mention briefly that tornadoes are more common in La Nina years - with the cooler air as Spencer, Michaels, and Watts say. What they don't mention is the effect of AGW on the cycles and intensities of the ENSO/El Nino/La Nina events.

Here's what Trenberth actually said, and note the part of the quote that was omitted from Taylor's recount in the OP's link:
http://wonkroom.thinkprogress.org/2011/ ... le-denial/

In an email interview with ThinkProgress, Dr. Kevin Trenberth, one of the world’s top climate scientists, who has been exploring for years how greenhouse pollution influences extreme weather, said he believes that it is “irresponsible not to mention climate change” in the context of these extreme tornadoes. Trenberth, head of the Climate Analysis Section of the National Center for Atmospheric Research, added that the scientific understanding of how polluting our atmosphere with billions of tons of greenhouse gases affects tornadic activity is still ongoing:

It is irresponsible not to mention climate change. … The environment in which all of these storms and the tornadoes are occurring has changed from human influences (global warming). Tornadoes come from thunderstorms in a wind shear environment. This occurs east of the Rockies more than anywhere else in the world. The wind shear is from southerly (SE, S or SW) flow from the Gulf overlaid by westerlies aloft that have come over the Rockies. That wind shear can be converted to rotation. The basic driver of thunderstorms is the instability in the atmosphere: warm moist air at low levels with drier air aloft. With global warming the low level air is warm and moister and there is more energy available to fuel all of these storms and increase the buoyancy of the air so that thunderstorms are strong. There is no clear research on changes in shear related to global warming. On average the low level air is 1 deg F and 4 percent moister than in the 1970s.

Climate scientist Gavin Schmidt, climate modeller at the NASA Goddard Institute for Space Studies, concurred:

It is a truism to say that everything has been affected by climate change so far and therefore this latest outbreak must in some sense have been affected, but attribution is hard and the further down the chain the causality is supposed to go, the harder this is. For heat waves it is easier, for statistics on precipitation intensity it easier – there are multiple levels of good modelling, theory and observations to back it up. But we have much less to go on with tornadoes.(My emphasis added)

http://www.realclimate.org/index.php/ar ... l-warming/

How will the El Niño phenomenon be affected by a global warming?
This is what the Dutch Meteorological Institute (KNMI) and the Max-Planck Institute (Germany), Matt Collins of Univ. Reading (U.K.) think. There is even a short entry about global warming and ENSO in Wikipedia. The brevity of this entry may reflect the fact that the question about how ENSO will respond to a global warming is still not settled. However, it seems that one common trait among some climate models is the indication that a global warming may result in a more a general El Niño-type average state (eg. Collins et al. 2005, Climate Dynamics, 24, 89-104. 19 and here).

How could a change in the background state affect ENSO? There are a number of different theories which go in different directions, but part of the difficulty is that we cannot put our finger on one mechanism and say ‘this is the one!’. .............The picture may be even more complex, and a response in ENSO may even involve perturbations of the carbon cycle. The models are all over the place, and most climate models yield patterns with some bias either in geographical character, amplitude or time scales. Analysis by Collins of climate model simulations indicated that increased CO2 may result in ENSO events becoming larger in amplitude and more frequent than under present conditions. This conclusion was based on version 2 of the Hadley Centre Coupled Model (HadCM2). However, in a subsequent analysis based on version 3 of the Hadley Model (HadCM3), Collins found that he could not detect a change in magnitude or frequency of ENSO as greenhouse gases increased, thus contradicting the results of his earlier study. These differences highlight the level of uncertainty associated with ENSO and global warming.(Again, my emphasis)

That doesn't sound like "stubbornness and closed-mindedness" to me, but open honesty about where the state of the research is, with their hypotheses of how the weather events could be affected by AGW - the research to elucidate the mechanisms continues, but in now way means that there's nothing to it. Nor that they are being "alarmists trying to sell their message of gloom and doom."

In the wake of last week’s tragic tornado outbreak, the alarmists are inviting us to focus on the alleged connection between global warming and tornadoes. I agree – let’s indeed pay special attention to the tornado issue. The alarmists’ argument regarding tornadoes is a near perfect proxy for alarmist global warming arguments as a whole. The skeptical counter-arguments are a near perfect proxy for skeptical global arguments as a whole. Do you trust subjective speculation that is strongly and repeatedly contradicted by real-world facts, or do you trust the theory that is strongly and consistently supported by real-world facts? Answer this question regarding tornadoes, and you will similarly have your answer regarding the overall global warming debate.

Indeed, let's, and not just about tornadoes. Because I suspect that it's not "contradicted by real-world facts" as is asserted here. The question then becomes, will the skeptics be willing to accept those facts, and what they mean, themselves?