A message from the recovery room

Eli's immediate post below as reference. I haven't written anything yet because I've been meaning to first set aside several hours to recover where everything ended up. I think where my hubris messed things up was in that wasn't just those skepticalish abstracts I wanted to understand, but an attempt to get all discrepancies in any category resolved by forgetting the abstracts when reviewers disagreed and reading the source papers instead. That bridged too far for us volunteers and ended it.

Still could be a good thing just to read the papers for the skeptical abstracts. I think some of the implicit doubting might go away (not all of it). That info could feed into the other studies.

Eli's done a great job resurrecting the work we all did.

Rose gets stuck on statistical significance

Too many takedowns to count for David Rose who doesn't realize that short-term fluctuations in temperature tell you little about long term trends.  The latest case is that according to one computer model, the temperature sequence ending in 2012 is close to the bottom edge of the statistical uncertainty range, a point where there's only supposed to be a 5% chance that random variation produces a temperature below the modeled range. Rose thinks this means an end to warming.

The above link shows a broader set of models gives a wider uncertainty range.  And anyway, it's within the uncertainty range for the more sensitive model albeit near the lower edge.

The being near the edge is where our Rose gets stuck. A little over two years ago, Rose declared that global warming had halted since 1995. His proof - while measured temperature had risen since 1995, the amount of rise was only near the edge of being statistically significant:

Phil Jones replies: "The key statement here is 'not statistically significant'. It wasn't for these years at the 95% level, but it would have been at the 90% level. If you add the value of 0.52 in for 2010 and look at 1995 to 2010 then the warming is statistically significant at the 95% level." [What this means is that the warming trend for the past few years previously met a lower test of statistical significance. With addition of the results so far for 2010, it now means the higher test.]

So according to Rose, being near the edge may as well be proof if it's on the cold side, but means nothing at all if it's on the warm side.

Might also be worth noting that given decades of data, random variation will actually push the actual result outside the 5%-95% band at some points.

Key the extremes to their context

(via Climate Central.)

I'm not sure yet what I think of Mark Kleiman's post about how people always accept their side's arguments on a position and assume a contrary argument means the arguer is on the other team.  I'm no fan of centrism-worship, or of contrarianism-for-its-own-sake.  OTOH, a critical eye on the arguments used for our own side has some moral value.

In that sense, the 2012 record warmth in the lower 48 states, a record for 1.58% of the planet's surface for a single year, is getting overplayed.  At least, the key front and center should be context, that year after year, record highs generally exceed record lows, and that generally consistent result is significant additional support to the mountain of evidence for climate change.  What's important about 2012 in the lower 48, outside of bringing the American public mainstream a little a closer to the scientific mainstream, is how it reminds us of that context.*

Lose the context and you get big pronouncements like this from Watts Up:  "Low temperature records overwhelm highs in the USA this past week" (emphasis added).  Context may not cure foolishness, but it might help a little bit.


*One exception is if the 2012 record highs are so unprecedentedly big that natural variability couldn't ever explain them, equivalent to rolling two dice and having them come up 13.  That would be important, but I've missed any in-depth discussion of that possibility.

Fluoridating water, or a funny thing happened on my way to backseat driving

I originally labelled this blog Backseat Driving back in 2004 because I anticipated it to be a blog where I would second-guess decisions made by politicians and other people. That worked out fine more or less until November 2010, when for some reason I was elected to the Santa Clara Valley Water District Board. Turns out that San Jose is the largest city in the US without fluoridated water supplies (in much of the city, anyway), and the seven of us directors have to decide whether we'll help or hinder the fluoridation process. So I'm pushed into the front seat for this one.

We've got some legal and economic issues to handle (it's not quite as cheap as everyone says, I want to know where the money's going to come from), but the relevant issue here is science. I read the guest post at climate blogger Coby Beck's place, The Case Against Fluoride, fairly closely a while back, especially the raucous debate in the comments. As a spectator with some, limited reading of the available information, I'd say the fluoridators seemed more persuasive than skeptics, but it wasn't the absolute demolishing that I expected.

The fluoride skeptics really hurt their cause when say fluoride doesn't prevent cavities - it's so obviously effective that people making this claim are damaging their own credibility. I'd consider it comparable to denying that the planet has warmed in the last 50 years.

The closer issue is adverse effects, and whether a substantial number of people are very slightly harmed by fluoridation, or if a small number of people are substantially harmed. The 2006 National of Sciences report doesn't condemn fluoridation, but it doesn't absolve it, either:

Bone Fractures

....Overall, there was consensus among the committee that there is scientific evidence that under certain conditions fluoride can weaken bone and increase the risk of fractures. The majority of the committee concluded that lifetime exposure to fluoride at drinking-water concentrations of 4 mg/L or higher is likely to increase fracture rates in the population, compared with exposure to 1 mg/L, particularly in some demographic subgroups that are prone to accumulate fluoride into their bones (e.g., people with renal disease)....There were few studies to assess fracture risk in populations exposed to fluoride at 2 mg/L in drinking water. The best available study, from Finland, suggested an increased rate of hip fracture in populations exposed to fluoride at concentrations above 1.5 mg/L. However, this study alone is not sufficient to judge fracture risk for people exposed to fluoride at 2 mg/L. Thus, no conclusions could be drawn about fracture risk or safety at 2 mg/L....

(In California, 2 mg/L was the limit, and 0.7 is the new proposed goal. -Ed)

Neurotoxicity and Neurobehavioral Effects

Animal and human studies of fluoride have been published reporting adverse cognitive and behavioral effects. A few epidemiologic studies of Chinese populations have reported IQ deficits in children exposed to fluoride at 2.5 to 4 mg/L in drinking water. Although the studies lacked sufficient detail for the committee to fully assess their quality and relevance to U.S. populations, the consistency of the results appears significant enough to warrant additional research on the effects of fluoride on intelligence....

Endocrine Effects

The chief endocrine effects of fluoride exposures in experimental animals and in humans include decreased thyroid function, increased calcitonin activity, increased parathyroid hormone activity, secondary hyperparathyroidism, impaired glucose tolerance, and possible effects on timing of sexual maturity. Some of these effects are associated with fluoride intake that is achievable at fluoride concentrations in drinking water of 4 mg/L or less, especially for young children or for individuals with high water intake. Many of the effects could be considered subclinical effects, meaning that they are not adverse health effects. However, recent work on borderline hormonal imbalances and endocrine-disrupting chemicals indicated that adverse health effects, or increased risks for developing adverse effects, might be associated with seemingly mild imbalances or perturbations in hormone concentrations. Further research is needed to explore these possibilities....

Genotoxicity and Carcinogenicity

....Whether fluoride might be associated with bone cancer has been a subject of debate. Bone is the most plausible site for cancer associated with fluoride because of its deposition into bone and its mitogenic effects on bone cells in culture....Several epidemiologic investigations of the relation between fluoride and cancer have been performed since the 1993 evaluation, including both individual-based and ecologic studies. Several studies had significant methodological limitations that made it difficult to draw conclusions. Overall, the results are mixed, with some studies reporting a positive association and others no association.

On the basis of the committee’s collective consideration of data from humans, genotoxicity assays, and studies of mechanisms of action in cell systems (e.g., bone cells in vitro), the evidence on the potential of fluoride to initiate or promote cancers, particularly of the bone, is tentative and mixed. Assessing whether fluoride constitutes a risk factor for osteosarcoma is complicated by the rarity of the disease and the difficulty of characterizing biologic dose because of the ubiquity of population exposure to fluoride and the difficulty of acquiring bone samples in nonaffected individuals.

These were the most troubling findings, mostly about what hasn't been proven, and mostly dealing with levels that are five times what's planned for drinking water. The report expressly ignored the benefits of fluoridation. It's important to balance out potential concerns over rare, severe complications related to fluoride with the certainty that rare, severe complications can result from cavities.

The bottom line as a policy maker in my little arena is that I shouldn't try and figure out the science myself, but I should try to figure out what the scientific consensus is, figure out where the consensus doesn't yet exist, and then plug that information into everything else we have to balance.

The science seems to favor fluoridation, but it's not a slam dunk. And we still have potential policy barriers, and the overall cost issues. Figuring this all out will be interesting.

UPDATE: I'll give the anti-fluoridators credit for quickly finding their way here. Personally, I'm not going to attempt to judge the quality of their sources. I don't care what any single paper or PhD says, I want to know what the consensus says.

Hoisted from the comments: it's the dog that doesn't bark that tells the story

Jeff S. says:

Your last point [failure of skeptics to create an alternative to hockey stick analysis is significant -ed.] is similar to another point you made on this blog that I don't think gets made often enough, or really, ever. If it is possible to construct a plausible, defensible climate model wherein a doubling of atmospheric CO2 leads to minimal warming, it is reasonable to expect that the allied forces of the fossil fuel industry (the largest industry in the world) and the skeptic community could have produced one by now. As Sherlock Holmes might have it, it's the dog that doesn't bark that tells the story.

(Links added by me.)

Of course I like the comment since it goes along with my view, but I wish I thought of the Sherlock Holmes piece.

What I think about global warming

I've stolen the headline and most of "my" thoughts on the issue from a good post by William that people should read.  But enough with the praise, let's focus on the smaller points where I might disagree.

William writes:

The main points that most would agree on as "the consensus" are:

1. The earth is getting warmer (0.6 +/- 0.2 oC in the past century; 0.1 0.17 oC/decade over the last 30 years (see update)) [ch 2]

2. People are causing this [ch 12] (see update)

3. If GHG emissions continue, the warming will continue and indeed accelerate [ch 9]

4. (This will be a problem and we ought to do something about it)

I've put those four points in rough order of certainty. The last one is in brackets because whilst many would agree, many others (who agree with 1-3) would not, at least without qualification. It's probably not a part of the core consensus in the way 1-3 are.

---

Yep, all of that remains pretty well true, and remains the core....In the years since I wrote that nothing has come along to overturn any of that, and much has come in to buttress it....However, I still think there is room for honest skepticism and disagreement about point 4.... The real argument should be about point 4: that it will be a problem and we should do something about it....I don't know the answer to point 4, and I know that I don't know :-). 

So let's stop there for a moment.  I think it's better to split point 4 into:

4.a.  This will be a problem.

4.b. (We ought do something about it).

I don't think it's reasonable for anyone to acknowledge point 3, especially acceleration, and deny 4.a.  Even in the imaginary world where benefits in some areas outweigh the problems in others, there are still problems.  And virtually no one really believes in that imaginary world - if we could wave a Pielkean magic wand, a technology that cheaply and safely scrubs all GHG emissions from the atmosphere, any reasonable person given a yes or no choice on waving that wand would do it.

As for 4.b., I'll just note that it's not an exclusively scientific question - engineers, economists, and wonderful wonderful lawyers all play a part, not to mention the general public that pays the bill one way or another.  No wonder it's a squishier issue.

Also on 4.b., I think if we drop two unstated assumptions in much of the climate discussion - first, that the universe ends in the year 2100, and second, new GHG emissions will magically cease the moment we hit 2x present CO2 equivalent levels - then we know the answer.  Maybe someone could argue we still have a decade or so of playtime available before doing something about the problem but that would both be unwise and not relevant to 4.b.

Finally, I may not know anything more about ocean acidification than William notes in original post (probably less), but it's really a separate scientific consensus issue that doesn't even depend on climate change being real.  My amateur opinion is that acidification consensus is as solid as the climate consensus through its own version of 4.a., and on policy matters the issue pushes for the same policy solutions as climate change other than some geoengineering and ocean sequestration proposals, and possibly on a slightly longer timeframe.


UPDATE:  I continue to think, without much evidence to back it up, that the biggest human cost from GHGs will be malnutritrion-related deaths in areas of subsistence agriculture and fishing due to precipitation shifts and acidification.  Not necessarily an increase against the present baseline but an increase against a future baseline where the world aggressively reduces GHGs.

Do the skeptics have a point about a 300-year typo in the IPCC?

(Welcome, Just One Minute readers. I appreciate Tom's link, but I'd also encourage you to look at my proposed bets with people who dispute anthropogenic global warming. With a few honorable exceptions, the loudest skeptics have been very uninterested in putting their money where there mouths are.)

Skeptics say:

According to Prof Graham Cogley (Trent University, Ontario), a short article on the future of glaciers by a Russian scientist (Kotlyakov, V.M., 1996, The future of glaciers under the expected climate warming, 61-66, in Kotlyakov, V.M., ed., 1996, Variations of Snow and Ice in the Past and at Present on a Global and Regional Scale, Technical Documents in Hydrology, 1. UNESCO, Paris (IHP-IV Project H-4.1). 78p estimates 2350 as the year for disappearance of glaciers, but the IPCC authors misread 2350 as 2035 in the Official IPCC documents, WGII 2007 p. 493!

I tried to run down the truth in a comment thread:

Let's go p. 493, shall we?

"Glaciers in the Himalaya are receding faster than in any other
part of the world (see Table 10.9) and, if the present rate
continues, the likelihood of them disappearing by the year 2035
and perhaps sooner is very high if the Earth keeps warming at
the current rate. Its total area will likely shrink from the present
500,000 to 100,000 km2 by the year 2035 (WWF, 2005)."

http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter10.pdf

The WWF cite:

"WWF (WorldWildlife Fund), 2005:An overview of glaciers, glacier retreat, and
subsequent impacts in Nepal, India and China.WorldWildlife Fund, Nepal Programme,
79 pp."

On to the WWF:

In 1999, a report by the Working

Group on Himalayan Glaciology (WGHG) of the International Commission for Snow and Ice

(ICSI) stated: “glaciers in the Himalayas are receding faster than in any other part of the world

and, if the present rate continues, the livelihood of them disappearing by the year 2035 is very

high”.

The ISCI is where I run out of direct online sources. But I did find this ref, also from 1999:

"The glacier will be decaying at rapid, catastrophic rates. Its total area will shrink from the present 500,000 to 100,000 square km by the year 2035," says formerICSI president V M Kotlyakov in the report Variations of snow and ice in the past and present on a global and regional scale.

This is a problem. Back to Kotlyakov's report (p. 66):

The degradation of the extrapolar glaciation of the Earth will be apparent in rising ocean level already by the year 2050, and there will be a drastic rise of the ocean thereafter caused by the deglaciation-derived runoff (see Table 11 ). This period will last from 200 to 300 years. The extrapolar glaciation of the Earth will be decaying at rapid, catastrophic rates— its total area will shrink from 500,000 to 100,000 km² by the year 2350.

If the IPCC's chain of citations does indeed reach back to and rely on Kotlyakov 1996 alone - and I'm not sure that it does - then the skeptics have a point. Worth noting that Kotlyakov assumed linear changes in warmth, which is optimistic under business-as-usual scenarios, but that won't erase a 300-year difference.

UPDATE: Skeptic Tom Maguire gets a little further than me, but no real results. So far it's looking like sloppy work, although the sloppiness isn't with the IPCC but the predecessor citations. Maybe someone else can get a better answer than Tom or me.

Adding geologic weathering cycles to a wiki climate article

The wiki climate article Long-term effects of global warming has been criticized from reputable sources (not the usual scruffy crew) as being alarmist. To fix that and because it seemed like a good place anyway, I've added a short section on how the oceanic absorption and geologic weathering over many thousands of years will eventually take care of the CO2. It's here, but could use some additional info.

Quenching CO2 saturation but not CO2 litigation

Two climate miniposts:

First, Rabett discusses the "quenching" phenomenon that explains why CO2 infrared absorption isn't quickly saturated here, with much more in the comments. I had never understood the idea that the energy from CO2-absorbed radiation is transferred by direct physical contact with other molecules instead of being re-emitted. The part I still don't understand then is whether saturation could ever limit IR absorption so long as there's plenty of non-greenhouse gas molecules in the atmosphere to do the quenching.

Second, the lawsuit against the California waiver that allows California (and many other states following California's lead) to set greenhouse gas emissions for vehicles is back on again, despite the automaker commitment not to sue. The auto dealers are suing instead, in a typical trick. I agree with Warming Law that this isn't a moot issue, despite the fact that the feds have now adopted California's standards. It's a backstop against something going wrong with a federal effort (or, gods help us, a denialist Republican elected president in 2012). It also reinforces the legitimacy of the Clean Air Act waiver process which has been granted in virtually all cases before it became politically inconvenient for the fossil fuel industry and their political minions. California may need to do this again in the future, so we need to keep the option open.