I continue to be amazed at how Gavin Schmidt and Eric Steig are so convinced of their viewpoints, that they fail to see that their autocratic tenor and tone is turning off many of their colleagues. In my engagement with them at Real Climate, apparently, I never learn either (see). :-)
Here are the latest comment/replies on the Real Climate weblog reproduced below
Eric – Please elaborate, however, on why hypotheses 2a and 2b are not sufficiently distinct. The 19 authors of our 2009 EOS paper concluded that they are. Hypothesis 2b is clearly the emphasis of the 2007 IPCC reports.
As we wrote in our article
“The evidence predominantly suggests that humans are significantly altering the global environment, and thus climate, in a variety of diverse ways beyond the effects of human emissions of greenhouse gases, including CO2. Unfortunately, the 2007 Intergovernmental Panel on Climate Change (IPCC) assessment did not sufficiently acknowledge the importance of these other human climate forcings in altering regional and global climate and their effects on predictability at the regional scale.”
Also, you state that Hypothesis 2a is not original. Please refer us to where this perspective is discussed in the IPCC (and CCSP) reports.
[Response: Eric can speak for himself, but other forcings are discussed in WG1 Chapter 2, section 2.3, 2.4, 2.5, through most of chapter 6, and all of chapter 7. The dominance of CO2 among the greenhouse gases is seen in fig 2.20 and fig 2.21 as well as the diversity of other forcings. - gavin]
[Response: To answer your question about hypotheses 2a and 2b, it simply depends on what aspect of the climate system you are talking about. In many land areas, deforestation has a huge impact on the local climate, certainly larger than CO2, so far (Hypothesis 2a). In the central Pacific, it is certainly not land use that dominates; CO2 probably does (Hypothesis 2b). To suggest these are mutually exclusive is just wrong.
Response #1: June 25 2010
It appears that Eric, although he apparently does not want to admit it (perhaps even to himself), provides evidence to reject Hypothesis 2b. If in parts of the climate system, non-CO2 human climate forcings are more important than CO2 radiative forcing, than Hypothesis 2b must be rejected.
We do need to better define what aspects of the climate system are important to society and the environment. In the 2005 NRC report
National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp.
it is written
Despite all these advantages, the traditional global mean TOA radiative forcing concept has some important limitations, which have come increasingly to light over the past decade. The concept is inadequate for some forcing agents, such as absorbing aerosols and land-use changes, that may have regional climate impacts much greater than would be predicted from TOA radiative forcing. Also, it diagnoses only one measure of climate change—global mean surface temperature response—while offering little information on regional climate change or precipitation. These limitations can be addressed by expanding the radiative forcing concept and through the introduction of additional forcing metrics. In particular, the concept needs to be extended to account for (1) the vertical structure of radiative forcing, (2) regional variability in radiative forcing, and (3) nonradiative forcing.
In our 2009 EOS article, we concluded
In addition to greenhouse gas emissions, other first- order human climate forcings are important to understanding the future behavior of Earth’s climate. These forcings are spatially heterogeneous and include the effect
of aerosols on clouds and associated precipitation [e.g., Rosenfeld et al., 2008], the influence of aerosol deposition (e.g., black carbon (soot) [Flanner et al. 2007] and reactive nitrogen [Galloway et al., 2004]), and the role of changes in land use/land cover [e.g., Takata et al., 2009]. Among their effects is their role in altering atmospheric and ocean circulation features away from what they would be in the natural climate system [NRC, 2005]. As with CO2, the lengths of time that they affect the climate are estimated to be on multidecadal time scales and longer.
Apparently, Eric has chosen to ignore this broader view of the human role in the climate system, which necessarily requires that Hypothesis 2b be rejected.
Response #2: June 25 2010
Gavin – You accept Hypothesis 2b. Thank you for answering clearly. Our EOS paper concluded otherwise, and it is informative to have a discussion by your readers of the three hypotheses on Real Climate. I look forward to reading them.
[Response: Please do not put words into my mouth. First of all, I do not recognise your statements as hypotheses in any useful sense. Secondly, I see no contradiction in accepting that there are multiple sources of anthropogenic influences on climate (I think we will have over a dozen independent effects in the AR5 simulations we are doing), and acknowledging that because of the rate of the rise and the perturbation lifetime of CO2 emissions that they are the dominant issue moving forward. However that does not imply that only CO2 emission cuts are useful, and if you look at any of our recent policy-related work (Shindell et al, 2009; Unger et al, 2009), you will see a portfolio approach to calculating the impact of specific policies and sectors. See also this piece in Physics World. Thus neither 2a nor 2b properly encompass my views. Other forcings are neither negligible nor is CO2 just one issue among the rest. - gavin]
Gavin fails (deliberately?) to accurately present what our three hypotheses actually state. In Hypothesis 2b, we do not state that the other human climate forcings are negligible, just that the dominant human climate forcing is the radiative forcing from CO2, as is assumed by the IPCC. When Gavin writes
“acknowledging that because of the rate of the rise and the perturbation lifetime of CO2 emissions that they are the dominant issue moving forward”
this is a rejection by Gavin of Hypothesis 2a [whose rejection conflicts with what Eric has written in his response].
Finally, statements by Eric such as
Response: To use an overused metaphor, you are basically asking “Do you still beat your wife, sir?”. The point is that the “AGW” mainstream (at least, as represented by the IPCC) is not in conflict with Pielke’s position, at least not the way it is expressed by you. As I note above the real problem with his position is that it is a false dicotomy. Both 2a and 2b are correct depending on what part of the system you are talking about. Pielke Sr. makes it sound like the ‘mainstream’ is missing something when they aren’t. Hence the definition of a loaded question: one that presupposes something that has not been proven or accepted by all the people involved. If Pielke Sr. gets classified as a skeptic, or contrarian, or whatever, it is due to this sort of misleading rhetoric. It may not purposefully intend to mislead, but it is misleading nevertheless, and in quite substantive ways (because it implies that the mainstream view that we probably ought to cut CO2 emissions is based on faulty science). Note, however, this none of this has anything to do with Anderegg et al., except that, if in fact he gets classified as a ‘denier’ in their analysis, this is probably why. –eric]
[Response: Being listed on our blogroll does not constitute endorsement. In general, the sites we do list — whether they are run by scientists or not — tend to get the science right much of the time, and hence are consistent with our mission. Being not-listed could mean that a) we haven’t heard of the site, b) that it is uninteresting or unimportant, or c) that we consider it dishonest or disingenuous with respect to the science. Pielke Jr, Blackboard, and ClimateAudit all fall squarely into the latter category.–eric
illustrate their continued use of ad hominem labels to attempt to promote their viewpoint rather than constructively engage in the discussion of the science. Unfortunately, this also means that when they (and those colleagues who agree with them) review one of my proposals or papers (and those others with whom Gavin and Eric disagree), they likely are going to provide biased reviews. This is why the term “black list” is so appropriate.