by Judith Curry
Climate change, once considered a problem for the distant future, has moved firmly into the present. Climate change is already affecting the American people. – U.S. NCADAC
The U.S. National Climate Assessment Report was published Tuesday [link]. I’ve read half of the chapters (at the beginning and end), skimming the ones in the middle.
My main conclusion from reading the report is this: the phrase ‘climate change’ is now officially meaningless. The report effectively implies that there is no climate change other than what is caused by humans, and that extreme weather events are equivalent to climate change. Any increase in adverse impacts from extreme weather events or sea level rise is caused by humans. Possible scenarios of future climate change depend only on emissions scenarios that are translated into warming by climate models that produce far more warming than has recently been observed.
Some of the basic underlying climate science and impacts reported is contradictory to the recent IPCC AR5 reports. Pat Michaels and Chip Knappenberger have written a 134 page critique of a draft of the NCADAC report [link].
Even in the efforts to spin extreme weather events as alarming and caused by humans, Roger Pielke Jr. has tweeted the following quotes from the Report:
- “There has been no universal trend in the overall extent of drought across the continental U.S. since 1900”
- “Other trends in severe storms, including the intensity & frequency of tornadoes, hail, and damaging thunderstorm winds, are uncertain”
- “lack of any clear trend in landfall frequency along the U.S. eastern and Gulf coasts”
- “when averaging over the entire contiguous U.S., there is no overall trend in flood magnitudes”
As a I wrote in a previous post on a draft of the report, the focus should be on the final Chapter 29: Research Agenda, which outlines what we DON’T know. Chapter 28 Adaptation is also pretty good. Chapter 27 Mitigation is also not bad, and can hardly be said to make a strong case for mitigation. Chapter 26 on Decision Support is also ok, with one exception: they assume the only scenarios of future climate are tied to CO2 emissions scenarios.
An interesting feature of the report is Traceable Accounts – for each major conclusion a Traceable Account is given that describes the Key Message Process, Description of evidence base, New information and remaining uncertainties, Assessment of confidence based on evidence. The entertainment value comes in reading the description of very substantial uncertainties, and then seeing ‘very high confidence’. This exercise, while in principle is a good one, in practice only serves to highlight the absurdity of the ‘very high confidence’ levels in this report.
Apparently President Obama is embracing this Report, and the issue of climate change, in a big way, see this WaPo article For President Obama A Renewed Focus On Climate. Motherboard has an interesting article How extreme weather convinced Obama to fight climate change.
In an interesting move, Obama Taps TV Meteorologists to Roll Out New Climate Report, which describes how Obama is giving interviews to some TV weathermen. It will be interesting to see how this strategy plays out, since TV weathermen tend to be pretty skeptical of AGW.
The politics on this are interesting also, see especially these two articles
- White house set to lay out climate risks as it touts U.S. energy boom
- Podesta: Congress can’t stop Obama on global warming
While there is some useful analysis in the report, it is hidden behind a false premise that any change in the 20th century has been caused by AGW. Worse yet is the spin being put on this by the Obama administration. The Washington Post asks the following question: Does National Climate Assessment lack necessary nuance? In a word, YES.
The failure to imagine future extreme events and climate scenarios, other than those that are driven by CO2 emissions and simulated by deficient climate models, has the potential to increase our vulnerability to future climate surprises (see my recent presentation on this Generating possibility distributions of scenarios for regional climate change). As an example, the Report highlights the shrinking of winter ice in the Great Lakes: presently, in May, Lake Superior is 30% cover by ice, which is apparently unprecedented in the historical record.
The big question is whether the big push by the White House on climate change will be able to compete with this new interview with Monica Lewinsky :)