Next generation questions for global warming

June 27, 11:41 PMSF Environmental Policy ExaminerThomas Fuller

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As with all scientific hypotheses, global warming will have to stand up under scrutiny over time. As there is no recognised clearinghouse that presents objections and answers in a structured fashion, this leads to scattergun efforts where multiple objections are raised and only partially addressed in the same forum. Popular websites such as Grist, RealClimate and Skeptical Science have tried to offer responses to some 'skeptical' talking points, but there is no forum for exchanging views and referencing papers outside the rather impenetrable associations of individual specialties, which in any event limit their discussion to issues within the specialty.

Those supporting an activist solution to the threat of anthropogenic global warming complain (sometimes loudly) that they are forced to answer the same 'primitive' objections repeatedly, only to see them resurface shortly thereafter, something that I am sure is frustrating. It's a pity that a central resource can't be agreed on and that an exchange of both views and peer-reviewed papers cannot be established.

There is a new generation of skeptical arguments advanced against the theory of anthropogenic global warming. I hope they win--not because I am on their side, but because I want very much for the Earth not to face a serious threat--we have enough of them already. So far, it appears to me that this new generation of counter claims is not receiving individual attention, but is rather being classed in with earlier skeptical arguments.

So let me try and articulate some of them here and ask for a response.

Data gathering and analysis

1.  Anthony Watts of Watt's Up With That has surveyed 80% of the USHCN surface temperature measurement sites and found that only 11% of them meet siting specifications. The surface temperature increase that partially gave rise to concerns about global warming coincided with a move to tethered electronic measuring devices (um, I think that means thermometers) that forced the movement of many stations closer to buildings and developed areas, causing warming that may not have been corrected for.
2. Urban heat bias occurs when temperature measurements are influenced by development of heat sources near the thermometers. There are questions about whether this is accounted for correctly in analyses of surface temperatures.
3. Indeed, the NOAA has stopped correcting for urban heat bias altogether, and their suface temperature record is diverging from other sources. This is further complicated by the drop out of a large number of measurement stations.
4. Many temperature measurement records show a trend break at the same time that the measuring methodology has changed. Skeptics ask whether this has influenced the records arbitrarily.
5. The data from 3,000 Argos buoys appear to show a loss of heat in the ocean since 2003. This would seem to have important implications for AGW theory, if confirmed.
6. AGW theory predicts a warming of the tropical troposphere that has yet to be found. Again, if this warming is not found it would appear to have important implications about the efficacy of other projections of future climate.

Does uncertainty about the accuracy of measurements threaten AGW theory? Or does a verified rise in temperatures matter more than the exact start and stop points?

 Sensitivity, positive and negative feedbacks

(Question reworded based on input from Lucia Liljegren) Recently published papers indicate that the sensitivity of the atmosphere to forcing due to CO2 increase may actually be negative  less than previously thought. Other research indicates that  The IPCC calculation of 1.5 to 4.5 with a 'preference' (help with phrasing?) of 3.5 may be too high. If true, this would greatly reduce the harm expected from a doubling of CO2 concentrations. Does recent research justify a change in the commonly accepted level of sensitivity of the atmosphere?

Plateau in current temperatures

In recent years temperatures have either plateaued or even declined slightly, depending on the dataset examined and smoothed averages used. Although temperatures could not be expected to move in a straight line, this leveling off during a period of heavy emissions of CO2 seems significant to skeptics. Does this speak to the skill of models in any meaningful way?

Tipping point

Some scientists have postulated that there is a point in the near future (or present, or even past) beyond which CO2 emissions are certain to cause great harm to the environment. However, the scientific basis for this seems unclear, and the timing of these announcements is at the very least useful to the political agenda in Western countries considering definitive action on CO2 emissions.

How confident can the public be in the disinterested viewpoint normally expected from scientists?

Other primary climate forcings

Roger Pielke Sr. has published repeatedly on the possibility that other anthropogenic actions influence the climate, ranging from deforestation and interruptions of the hydrologic cycle to land use policy and agricultural decisions. To what extent should we expect them to be additive to the changes brought about by CO2 emissions, and to what extent is it possible that climate change thought to be produced by CO2 emissions could in fact be due to other human causes?

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You will note that I do not bring up issues such as frequency and intensity of tropical storms, as they do not appear to address the core issues of anthropogenic global warming. If you think they should be included, we'll discuss another time.

So. I'm not an expert on climate change, and I'm not a scientist. What salient questions did I miss? What do I present as new questions that in fact are old? What questions did I mis-phrase? And, of course, what are the answers?

If any scientists or others who wish to provide extensive input would like to reply by email, which would remove the restrictions imposed by our comments section, feel free to send them to thomaswfuller3 at gmail dot com, and I will post them here as updates.

Update: Bart Verheggen, principal contributor to Our Changing Climate, forwards this:

Over at the Examiner, Thomas Fuller had a post outlining a ‘new generation of skeptical arguments against the theory of anthropogenic global warming’ (AGW), which he felt had a lot of merit. I got to his post via a comment thread at RealClimate, where he asked for input. He did get quite a lot of feedback, but unfortunately, a lot of it was packaged in a rather negative tone. (I’ll come back to communication strategies in another post.) Since he appeared to be sincerely interested, I felt compelled to react. I responded to (his framing of) his questions as follows:

You frame your questions/topics as “skeptical arguments advanced against the theory of anthropogenic global warming”. You also acknowledge that scientists are getting frustrated “answering the same ‘primitive’ objections repeatedly, only to see them resurface shortly thereafter, something that I am sure is frustrating.” I think a logical consequence is that your framing of the topic arouses a defensive reaction from climate scientists and their supporters. Based on you being aware of the scientists’ frustration in this matter, your choice of framing is rather odd, and so is your surprise about the reactions you received at RealClimate (mostly from commenters by the way; not from the RC editors). In between the snark, you did get some feedback there as to the contents of your questions/topics. It’s your choice whether to focus attention on the former (the snark) or the latter (the feedback to the content).

Most points on your list are neither new nor a threat to the theory of anthropogenic global warming. That said, some of your points have some validity in that the related uncertainties are large. Reframing your questions as “which areas in climate science have the greatest uncertainties?”, opens the door to a more constructive discussion. 

A quick glance at the points your raise:

Data gathering and analysis. Points 1-4 are pretty meaningless for reasons explained at length elsewhere. The revised ocean heat content data (nr 5) don’t show a decrease of ocean heat content AFAIK, and moreover, trends have to be decided upon at appropriately long timescales. I’m not familiar enough with Tropical troposphere trends to comment on, though Santer et al (2008) found no discrepancy between modeled and measured tropical tropospheric temperatures.

Climate sensitivity and feedbacks. There is considerable uncertainty in the precise value of climate sensitivity, so in my newly proposed frame, this would be a valid point. However, taking all constraints on climate sensitivity into account, it seems very unlikely that it is far outside the boundaries you quote: 1.5 to 4.5 degrees for a doubling of CO2. The chance for all previous work to be shown totally wrong by one new piece of work is perhaps not nil, but it definitely is very small.

Plateau in current temperatures. Trends have to be decided upon at appropriately long timescales. The apparent plateau is close tomeaningless for deciding on climatic trends. This truly is an old classic that gets scientifically minded persons’ defenses up.

Tipping points. The exact nature and especially timing of tipping pointsis extremely uncertain, so yes, this is an area where the existing knowledge is very limited. However, the limited knowledge we do have (mainly based on paleoclimate) points to the existence of tipping points, eg related to the amount of ice cover. The policy relevance may be limited to “If it’s bad, it’s really bad. If it’s good, it’s still pretty bad”.

Other climate forcings. No news there. Those other forcings are taken into account and indeed, they are additive to the changes from GHG emissions. They do not negate the radiative properties of those greenhouse gases however. Also keep in mind that many of the stronger feedbacks respond to temperature, so the amplification (or dampening) of the temperature response does not differ greatly between different forcings. That means that there is not a huge amount of wiggle room to decrease (or increase) the importance of the role of greenhouse gases (at least not without violating basic physics).

I would add one more point: Aerosols. The uncertainty surrounding them and their impact on climate change is very large. But again, don’t expect a landslide change in current wisdom just because of that. That would be wishful thinking.

It is good to keep in mind that uncertainty is not the same as knowing nothing, and that uncertainty can go both ways: for the better or for the worse. We’ll have to make decisions in the face of uncertainty, whether we like it or not. Climate policy should be about rational risk assessment, based on solid science.