John Christy, Richard McNider and Roy Spencer trying to overturn mainstream science by rewriting history and re-baselining graphs

February 22, 2014 by

Who are the Flat Earthers?

Before the advent of modern climatology, common wisdom had it that we tiny humans couldn’t possibly influence climate. Modern science shows we can. Yet John Christy and Richard McNider claim the exact opposite in a recent WSJ op-ed, in which they claim that their outdated views on climate somehow make them modern-day Galileo’s (or in their words: Why they are the ones declaring that the earth is round while the vast majority of the climate scientists persist in thinking the earth is flat). They couldn’t be more wrong.

Back then, scientific evidence slowly overturned the religious-cultural notion that the Earth was the centre of the universe. This resulted in a scientific consensus that the Earth revolves around the sun. More recently scientific evidence has started overturning the notion that humans can’t possibly influence something as gigantic as the Earth’s climate. This too has resulted in a scientific consensus  (though a public consensus is still lagging behind). In both cases, the pre-scientific notion was mostly culture-based, as opposed to being evidence-based.

As Jeff Nesbit tweeted: “Being the last scientist to accept established climate science doesn’t make you Galileo.” Quite the opposite indeed.

The Galileo-complex also suggests a rather simplistic view of how science progresses. Rather than a lone skeptic overthrowing a scientific (rather than a cultural) consensus, scientific progress is a usually a gradual process. New evidence has to be reconciled with the existing mountain of evidence; it doesn’t simply replace it. Observing a bird in the air doesn’t disprove gravity. “Skeptics” and their supporters often bring up Galileo as an example of that the scientific consensus can also be wrong, and has been wrong in the past. True enough, though as Carl Sagan said: “they laughed at Galileo, but they also laughed at Bozo the clown”.

Hot spot

Besides their entirely misplaced Galileo-framing, Christy and McNider also make a range of unsupported and/or incorrect statements. One argument deals with the so-called tropical tropospheric hot spot. This refers to the expected stronger warming of the tropical troposphere as compared to the surface. This “hot spot” is independent of the cause of the warming. But what do Christy and McNider write in the WSJ:

(the warming of the deep atmosphere is) the fundamental sign of carbon-dioxide-caused climate change, which is supposedly behind these natural phenomena

But hang on, didn’t Christy admit to the basic science that this hot spot is not specific to a greenhouse effect? Yes, he did (at the ClimateDialogue discussion in which he participated):

“Yes, the hot spot is expected via the traditional view that the lapse rate feedback operates on both short and long time scales. (…) it [the hot spot] is broader than just the enhanced greenhouse effect because any thermal forcing should elicit a response such as the “expected” hot spot.”

So why is he claiming something in the WSJ that he knows to be untrue?

Model-observation comparison

It almost goes without saying that any climate model-observation mismatch can have multiple (non-exclusive) causes (as succinctly summarized at RC):

  1. The observations are in error
  2. The models are in error
  3. The comparison is flawed

But rather than doing a careful analysis of various potential explanations, McNider and Christy, as well as their colleague Roy Spencer, prefer to draw far reaching conclusions based on a particularly flawed comparison: They shift the modelled temperature anomaly upwards to increase the discrepancy with observations by around 50%. Using this tactic, Roy Spencer showed the following figure on his blog recently:

Roy Spencer misleading figure - CMIP5-90-models-global-Tsfc-vs-obs-thru-2013

So what did he do? Jos Hagelaars tried to reproduce the different steps involved. A comparison of annual data, using a 1986-2005 baseline, would look as follows:

Jos Hagelaars - comparison_cmip5_hadcrut4_uah

Spencer used a 5 year running mean instead of annual values, which would (should) look as follows:

Jos Hagelaars - spencers-graph-reconstructed-part-1

The next step is re-baselining the figure to maximize the visual appearance of a discrepancy: Let’s baseline everything to the 1979-1983 average (way too short of a period and chosen very tactically it seems):

Jos Hagelaars - spencers-graph-reconstructed-part-2

Which looks surprisingly similar to Spencer’s trickery-graph. But critiquing Roy Spencer comes at a risk: He may call you a “global warming Nazi”. Those nasty CO2 molecules, that’ll teach them!

Many thanks to Jos Hagelaars for the data analysis and figures.

Is Climate Science falsifiable?

February 17, 2014 by

Guest post by Hans Custers. Nederlandse versie hier.

A very, ehhrmm… interesting piece on
Variable Variability, Victor Venema’s blog: Interesting what the interesting Judith Curry finds interesting. And I don’t mean interesting in a rhetoric, suggestive way; I mean it is a well-written and well-reasoned article, worth reading.

Victor writes about the meme regularly used by the anti climate science campaign, often supported by some straw man arguments, that the science of human impacts on climate would not be falsifiable. He shows it’s nonsense, by giving some examples of how it could be falsified. Or, more likely, already would have been falsified, if the science would be wrong. Victor’s post inspired me to think of more options to falsify generally accepted viewpoints in climate science. If there are any ‘climate change skeptics’ who want to contribute to real science, they might see this as a challenge. Maybe they can come up with a research proposal, based on one of the options for falsification. Like proper scientists would do.

First, a few more things about falsifiability in general. Bart wrote a concise post about the subject four years ago, explaining that a bird in the sky does not disprove gravity. What looks like a refutation at first, might on second thoughts be based on partial or total misunderstanding of the hypothesis. Natural climate forcings and variations do not exclude human impacts. Therefore, the existence of these natural factors in itself, cannot falsify anthropogenic climate change. A real skeptic is cautious about both scientific evidence and refutations. ‘Climate change skeptics’ like to mention the single black swan, that disproves the hypothesis that all swans are white. Of course that is true, unless that single black swan appears to be found near some oil spill.

Some of the falsifications that I mention later on might be somewhat cheap, or far-fetched. It is not very easy to find options to falsify the science of human impacts on climate. Not because climate scientists don’t respect philosophical principles of science, but simply because there’s such a huge amount of evidence. There are not a lot of findings that would disprove all the evidence at once. A scientific revolution of this magnitude only happens very rarely. Whoever thinks differently, doesn’t understand how science works. Read the rest of this entry »

The role of scientific consensus in moving the public debate forward

February 7, 2014 by

Mike Hulme had an interesting essay at The Conversation, the main message of which was

In the end, the only question that matters [for the public debate about climate change] is, what are we going to do about it?

Hulme correctly argues that the basic science is clear enough so that for society the important issues to discuss are not science related, but policy related. I argued much the same here. He writes:

What matters is not whether the climate is changing (it is); nor whether human actions are to blame (they are, at the very least partly and, quite likely, largely); nor whether future climate change brings additional risks to human or non-human interests (it does).

Let’s leave the minor quibble aside that AR5 puts the anthropogenic contribution at ‘extremely likely’ having caused more than half of the recent global warming.

The part where I disagree with Hulme is where he argues that showing the existence of a scientific consensus on the above (it is warming; it’s due to us; it’s bad news) somehow stands in the way of  getting society to discuss that most important question. I think the opposite is true. It is the continuous doubt about the science, sowed by those who oppose a serious discussion about what to do, that is a stumbleblock. Showing that a consensus amongst experts exists would enable society to more swiftly move on to the important conversation on what to do about it. I agree with Hulme that on this deeply ethical question there is, and ought to be, a multitude of opinions.

As Stephan Lewandowsky and John Cook write in a response to Mike Hulme:

The public’s perception of that scientific consensus is necessary to stimulate political debate about solutions.

Another element that’s missing from this discussion is that scientific and ideological arguments  should be clearly distinguished from each other (“is” vs “ought”).

Unfortunately, ideological arguments are often dressed in a sciency-looking cloak. From that perspective, I appreciate the honesty in Lindzen stating blunty “we’ll all be dead by then”, the obvious implication being: so why care. That’s indeed what a lot comes down to: How do you value the future compared the present?

Andrew Dessler’s testimony on what we know about climate change

January 19, 2014 by

In his recent testimony, Andrew Dessler reviewed what he thinks “are the most important conclusions the climate scientific community has reached in over two centuries of work”. I think that’s a very good choice to focus on, as the basics of what we know is most important, “at least as to the thrust and direction of policy” (Herman Daly). This focus served as a good antidote to the other witness, Judith Curry, who emphasizes (and often exaggerates) uncertainty to the point of conflating it with ignorance.

Dessler mentioned the following “important points that we know with high confidence”:

1.  The climate is warming.

Let’s take this opportunity to show the updated figure by Cowtan and Way, extending their infilling method to the entire instrumental period (pause? which pause?):

Cowtan and Way - Global Avg Temp 1850 - 2012

2. Most of the recent warming is extremely likely due to emissions of carbon dioxide and other greenhouse gases by human activities.

This conclusion is based on several lines of evidence:

- Anthropogenic increase in greenhouse gases

- Physics of greenhouse effect

- Observed warming roughly matches what is expected

- Important role of CO2 in paleoclimate

- No alternative explanation for recent warming

- Fingerprints of enhanced greenhouse effect (e.g. stratospheric warming cooling, which was predicted before it was observed)

Dessler:

Thus, we have a standard model of climate science that is capable of explaining just about everything. Naturally, there are some things that aren’t necessarily explained by the model, just as there’re a few heavy smokers who don’t get lung cancer. But none of these are fundamental challenges to the standard model.

He goes on to explain that the so-called “hiatius” is not a fundamental challenge to our understanding of climate, though it is “an opportunity to refine and improve our understanding of [the interaction of ocean circulation, short-term climate variability, and long-term global warming].”

What about alternative theories? Any theory that wants to compete with the standard model has to explain all of the observations that the standard model can. Is there any model that can even come close to doing that?

No.

And making successful predictions would help convince scientists that the alternative theory should be taken seriously. How many successful predictions have alternative theories made?

Zero.

3. Future warming could be large 

On this point I always emphasize that the amount of future warming depends both on a combination of factors:

- the climate forcing (i.e. our emissions and other changes to the earth’ radiation budget)

- the climate sensitivity (the climate system’s response to those forcings)

- the climate response time (how fast will the system equilibrates).

Internal (unforced) variability also plays a role, but this usually averages out over long enough timescales.

4. The impacts of this are profound.

In the climate debate, we can argue about what we know or what we don’t know. Arguing about what we don’t know can give the impression that we don’t know much, even though some impacts are virtually certain.

The virtually certain impacts include:

• increasing temperatures

• more frequent extreme heat events

• changes in the distribution of rainfall

• rising seas

• the oceans becoming more acidic

Time is not our friend in this problem.

Nor is uncertainty.

The scientific community has been working on understanding the climate system for nearly 200 years. In that time, a robust understanding of it has emerged. We know the climate is warming. We know that humans are now in the driver’s seat of the climate system. We know that, over the next century, if nothing is done to rein in emissions, temperatures will likely increase enough to profoundly change the planet. I wish this weren’t true, but it is what the science tells us.

Peter Sinclair posted a video of Andrew Dessler’s testimony. Eli Rabett posted Dessler’s testimony in full.

A key distinction in the two senate hearings was that Andrew Dessler focused on what we know, whereas Judith Curry focused on what we don’t know (though “AndThenTheresPhysics” made a good point that Curry goes far beyond that, by e.g. proclaiming confidence in certain benign outcomes (e.g. regarding sensitivity) while claiming ignorance in areas where we have a half-decent, if incomplete, understanding, e.g. regarding the hiatus). I have argued before that emphasizing (let alone exaggerating) uncertainties is not the road to increase people’s understanding of the issue, where what we do know is much more important to convey (if your goal is to increase the public understanding of scientific knowledge). Alongside that I argue that much more attention is needed to explain the nature of science, which is needed to e.g. place scientific uncertainties in a proper context.

CartoonUncertainty

Herman Daly said it as follows, in a quote I’ve used regularly over the past few years:

If you jump out of an airplane you need a crude parachute more than an accurate altimeter.

Arguing whether the altimeter might be off by a few inches is interesting from a scientific/technological perspective, but for the people in the plane it’s mostly a distraction.

Gavin Schmidt and Judith Curry on Science Advocacy

December 23, 2013 by

Gavin gave a fantastic talk at this year’s AGU conference about science advocacy (good report on it by Yale CMForum and Dot Earth). The video is available via the AGU youtube channel:

He argued that it’s best to be explicit about one’s values and clearly distinguish when one is talking values (“ought”) and when one is talking science (“is”). I entirely agree. I would add that it’s important to distinguish recommending a generic (e.g. mitigation) vs a specific (e.g. CCS) course of action, especially when the latter is not one’s area of expertise. I wrote about the public role of scientists before, which touches on many of these same issues.

Judith Curry also chimed in, complimenting Gavin but also giving some criticism, much of which is rather off-base imho.

Both Gavin and Judith refer to this statement by Thomas Stocker at the end of the (well worth watching) IPCC AR5 video:

Continued greenhouse gas emissions cause further climate change and constitute a multicentury commitment in the future.  Therefore we conclude that limiting climate change requires substantial and sustained reductions in greenhouse gas emissions.

Is this a normative statement (“ought”) or a factual statement (“is”)? Gavin claimed it’s the latter, Judith claimed it’s the former. It would be advocacy if the goal was left out, as in “we should reduce GHG emissions”. But that’s not what Stocker said. Instead, what he said comes down to “if this is the goal, then that is what needs to be done to achieve it”. Curry claims that adaptation, carbon sequestration or geoengineering would also be options to limit climate change. That’s only partly true. Adaptation doesn’t actually limit climate change, as the word says it means adapting to climate change. As such it helps in the short term (and is definitely important), but in the long term adaptation without mitigation is like mopping the floor while leaving the tap running (see also the Rabett). Carbon sequestration is a viable option to reduce atmospheric concentrations, but with current technologies it can only make a minor contribution. So it could limit climate change to a very limited extent one might say. Geoengineering is a more complicated story. Basically, it exchanges one type of climate change (temperature changes) with another type (hydrological changes), so it changes climate change.

Perhaps Stocker’s statement could have been made more specific by including e.g. something like “limiting climate change to what societies are adapted or can adapt to requires substantial and sustained reductions in GHG emissions” which I think is what he meant anyway.

Curry goes on to state ” And there is a missing element in this argument that warming is ‘bad’, which is a value judgment and has nothing to do with science.”

This is a strawman argument, as it’s not a (hidden) element in Stocker’s argument as given above. Again, it would be true if the goal was omitted or left implicit (but it wasn’t). If one feels that limiting climate change is not needed (because it’s not bad) than the needed cure (reducing emissions) is not needed, obviously. That is entirely consistent with what Stocker said.

Curry further offers the following list of “examples of potential hidden values that are rather inconvenient (because) these are why the public distrusts scientists as advocates”. I offer my comment with each (in italics). It’s not at all clear that these would all go in the direction of a bias in favor of the mainstream (as Curry seems to implicitly assume); to the contrary.

  • personal career advancement: Unclear in which direction this would most likely go.
  • research funding: idem, though this could cause a tendency to increase the apparent magnitude of uncertainties.
  • the value in terms of professional recognition (e.g. awards from professional societies) that supporting the scientific consensus can provide (recognizing the ostracism that con result from straying): No bigger reward for a scientist than to prove the scientific consensus wrong.
  • media attention: This goes in the direction of providing relatively more media attention to contrarian voices, Judith Curry herself being a good example (assuming that she wasn’t as prevalent in the media before her U-turn away from mainstream science). This got confirmed in the large survey amongst climate scientists that I conducted last year (not yet published).
  • influence within the scientific community: This hinges on using solid arguments, so usually provides the correct incentive.
  • influence at the power tables in terms public policy: Like with media attention, extreme voices seem to have disproportionate influence. Look at the regular line-up for US senate hearings for example. If you crave media attention and political influence, being loudly contrarian is a sure way to achieve that. In the Netherlands the same tendency is apparent.
  • broader political objectives that support any/all of the above: This goes more likely in the direction of downplaying rather than overplaying AGW I would argue.

Logical fallacies in assessing risks from climate change

December 9, 2013 by

Guest post by Hans Custers. Cross-posted at Planet3.  Nederlandse versie hier.

Fallacies of risk

We, humans, are not very good at estimating and weighing risks. Looking at the definition of risk, this is not so strange:

Risk = Probability * Effect

Most of us will have some understanding of both elements ‘Probability’ and ‘Effect’, but the combination of the two is rather abstract. In judging risks, we tend to focus on one of the two elements, and more or less neglect the other one. The figure below shows the difference between our perception of certain risks and their actual magnitude.

Risk perception and actual hazards

The definition of risk might suggest that it is always possible to calculate it, or give a quantitative estimate. But often, it’s not that easy. Sometimes, it can be difficult to define the exact “Effect”, and the parameter that can be used to quantify it. Effects can go from economic or financial costs to damage to nature, from a small decrease in well-being, to large numbers of casualties. Our judgment of risks depends a lot on the type of effect.

To make things even more complicated, the debate on risk often takes place at the border of science and politics, of logical reasoning and subjective judgment. Whatever we do to try and find objective parameters and criteria to assess and weigh risks, decisions what we do and what we do not find acceptable depend to some extent on value judgments. There are no 100% objective criteria to make these types of decisions.

It’s obvious that many fallacies can come up in this minefield for logic. Last week, Judith Curry blogged on the article “Fallacies of risk” by Sven Ove Hansson, trying to identify the fallacies in the debate on climate. In his article, Hansson seems to mainly focus on risks of (new) technologies, especially the ones with a low probability and large effects. Applying the same fallacies to the debate on climate is not as straightforward as it might seem. Curry seems to be making some mishaps. She ends up making quite a few comments on Hansson that totally miss the point. Here’s my attempt to improve on hers.

Read the rest of this entry »

Cowtan and Way global average temperature observations compared to CMIP5 models

November 15, 2013 by

It is well known that the Arctic is warming up much faster than the rest of the globe. As a consequence, datasets which omit this region (HadCRUT and NOAA) underestimate the global warming trend. A new paper by Cowtan and Way addresses this cool bias by using satellite data to fill in these data gaps. They make a good case that this method also improves upon the NASA GISS dataset, which uses extrapolated data from surface stations to partly fill in the data sparse regions. Combining their new method of infilling with the most up-to-date sea surface temperatures gives a substantially larger trend over the last 15 years than the abovementioned datasets do. The temporary slowdown in global surface warming (also dubbed “the pause”) nearly disappears. As Michael Tobis notes:

This demonstrates is how very un-robust the “slowdown” is.

The corrections don’t amount to a huge change in absolute temperature change, and the new data actually fall inside the uncertainty envelope provided by HadCRUT4. As the paper correctly states:

While short term trends are generally treated with a suitable level of caution by specialists in the field, they feature significantly in the public discourse on climate change.

In the figure below (made by Jos Hagelaars) the global average temperature as calculated by Cowtan and Way (“C&W hybrid”) is compared to both the HadCRUT4 dataset and the CMIP5 multi-model mean as well as its 5% and 95% percentile values (RCP8.5): [Update: The figure below has
been replaced, since the original was found to be in error during discussions on CA). The confidence interval of this corrected graph is substantially narrower than the erroneous original one. Note that the current graph shows the 5 to 95 percentile range of model runs (i.e. the 90% confidence interval), whereas the previous ones showed the 95% confidence interval. At the bottom of the post a similar figure with both confidence intervals as well as the two sigma range is shown.
]

Cowtan_Way_Hadcrut_RCP85_5-95_Perc

Also with these data improvements, recent observations are at the low side of the CMIP5 model range. The comparison of observations to models has to be interpreted with caution however. Some people like to jump to preferred conclusions, but it’s good to keep in mind that the expected warming at a specific point in time depends on a combination of factors. Any of these factors -as well as shortcomings in the observational data, such as those discussed by Cowtan and Way- could contribute to a mismatch between observations and models:

- radiative forcing

- equilibrium climate sensitivity

- climate response time

- natural unforced variability

The last factor means that one shouldn’t expect the multi-model mean (in which most variability is cancelled out) to be identical to the observations (which are the result of a particular realisation of natural variability).

Cowtan and Way made a very clear video in which the main results of their paper are explained in just a few minutes. Highly recommended watching:

More commentary on the paper on e.g. RC (Rahmstorf), SkS (Cowtan and Way), Guardian (Nuccitelli), P3 (Tobis), Victor Venema, Neven. See also this very useful background information provided by the authors.

[some typos corrected and clarifications added, 16-11. Erroneous figure replaced 21-11.]

Update: Below a similar figure as above, with different confidence intervals for the model runs shown. 

Cowtan_Way_Hadcrut_RCP85_V3

Update 2 (Feb 2014):

Jos Hagelaars added Cowtan and Way’s data for 2013 to a figure comparing observations to model projections:

Jos Hagelaars - comparison_cmip5_hadcrut4_cowtanway_2013

BBC interview: global warming pause, climate sceptics, long timescales

September 27, 2013 by

I was interviewed by Matt McGrath from the BBC last week, as were several other Dutch climate spokespeople (including PBL’s senior scientist Arthur Petersen and skeptical science writer/journalist Marcel Crok). Short parts of these interviews have appeared on the web  and on Radio 4 (“The World Tonight”, 26-09). Below I try to provide a bit of context to my quotes.

Both pieces are centred, as is fashionable these days, on the apparent smaller rate of surface warming in the past 15 years. The web piece is entitled “Climate sceptics claim warming pause backs their view”. Of course they claim it does. What sceptics did achieve –credit where credit is due- is to put this so-called “pause” on the agenda of mainstream media, until it got so fashionable that they all feel forced to use it as an anchor for any reporting on climate. But, as Gavin Schmidt is quoted as saying:

focus on a global warming pause over the past 15 years is a “misplaced” distraction that misses the big picture. He said, “The IPCC and the issue of climate change is not about the weather next year or the next five years; it’s about the long-term climate change that we are engendering.”

See also this useful figure from Stefan Rahmstorf, underscoring the silliness of drawing all too strong conclusions from 15-year trends.

giss2012c - Rahmstorf - Global temp with two silly trendlines

Figure showing NASA GISS global average temperatures with trendlines from 1992-2006 (light blue) and 1998-2012 (green) as well as the most recent 30-year trend in red. Naturally, starting in a very cold volcano-influenced or very warm El Nino influenced year will inflate or deflate the trend. (source: Stefan Rahmstorf)

I am quoted in the BBC piece as follows:

Bart Verheggen is an atmospheric scientist and blogger who supports the mainstream view of global warming. He said that sceptics have discouraged an open scientific debate.

“When scientists start to notice that their science is being distorted in public by these people who say they are the champions of the scientific method, that could make mainstream researchers more defensive.

“Scientists probably think twice now about writing things down. They probably think twice about how this could be twisted by contrarians.”

The discussion was about to what extent climate science isn’t open/transparent enough, as contrarians routinely claim. Matt also asked to what extent skeptics actually play a positive role in making science more open/transparent and more self-critical. I said ideally they would. People who are critical usually have a good influence that way. But many climate contrarians don’t just stop at raising partly valid criticism, but go on to distort the science. That has the opposite influence, as scientists noticing this behavior become more careful and more defensive, and(have to) think ahead how their words might get twisted by contrarians. So they may become less open and less frank, and more careful in how they chose their words.

That is the opposite of what contrarians claim they want to achieve, so it’s quite ironic (though entirely logical) that this is the more likely effect of their behavior. It shows quite a lack of self-awareness on their part that they don’t see how their actions and their behavior affect the dynamics of the public debate. For the worse, in most –though not all- cases.

There may also be some lack of self-awareness among the mainstream that they respond in a way that’s not conducive to a long-term open and frank dialogue with society. From an older comment of mine:

If the valid criticisms wouldn’t be packaged in such conspiratorial/accusative/exaggerated (c/a/e) ways, they would be welcomed much more than they currently are. The art that mainstream scientists and their defenders must learn is to take the valid parts of the criticisms and deal with/respond to them, and leave the c/a/e packaging for what it is. That is increasingly difficult because the critics and their supporters will try to keep the c/a/e in (presumably because this packaging is what is most effective at decreasing the scientists’ credibility and sowing doubt). That dynamic needs to be broken. It needs effort from both sides, as difficult and unfair as it sounds.

As I wrote in my earliest (and still rather positive) reflection on the Curry-turn:

There is a tendency of ‘circling the wagons’ within the scientific community, in response to the continuous attacks on the science. Attacks that are mostly based on smear and insinuation rather than solid arguments. (…) I think the ’us-versus-them’ feeling amongst many scientists and their supporters is understandable (as a reaction to the contrarian c/a/e attacks on the science), but counterproductive in the long run.

In the Radio 4 show (at ~33:50 min in; earlier in the downloadable mp3 version), I am saying a few things about the timescale of the problem and of the solution. I brought this up when the discussion was about whether we now have more time to respond to climate change. This is a vastly underappreciated point in the climate discussion:  The climate system will take much longer to cool down than it did to warm up. This is a consequence of how the carbon cycle works. In this context, I said the following:

We’re going somewhere, and if we don’t like where we’re going, we have to turn that wheel in time.  As when you’re on a giant supertanker on the ocean, you can’t say “oh, I’ll wait until I can feel the iceberg with my pinkie and then I’ll turn the wheel”. Then you’re a bit late, so you have to start doing that in time. That’s the other side of the coin. But if you keep banging the drum saying “it’s five to twelve! It’s five to twelve!” doesn’t work either. And that could be counter-effective to engage those who are a bit more skeptical.

Global warming is a problem in slow-motion, hence the “five to twelve” line is not the most useful one to get people on their feet, because if it remains five to twelve for too long, they will tune you out. That’s what happened in the aftermath of COP15 in Copenhagen for example (where the 5-to-12 line was used a lot, and not much has changed in the years since). The supertanker analogy is more appropriate I find, since that makes clear that even though the problematic situation that’s on your path isn’t in close proximity yet, it is necessary to change course, if you wish to avoid it.

Supertanker

Tropospheric hot spot

August 19, 2013 by

The current topic under discussion at ClimateDialogue is the tropospheric hot spot: Is it there, and if not, so what? Invited discussant are Steven Sherwood of the University of New South Wales in Sydney, Carl Mears of Remote Sensing Systems (working on the RSS satellite product) and John Christy of the University of Alabama in Huntsville (working on the UAH satellite product).

I’ll provide a short overview here (loosely based on the intro over at CD), interspersed with my own and other people’s commentary.

Based on theoretical considerations and simulations with General Circulation Models (GCMs), it is expected that any warming at the surface will be amplified in the upper troposphere. The reason for this is as follows: More warming at the surface means more evaporation and more convection. Higher in the troposphere the (extra) water vapour condenses and heat is released. Calculations with GCMs show that the lower troposphere warms about 1.2 times faster than the surface. For the tropics, where most of the moist is, the amplification is larger, about 1.4.

This means that, contrary to what some people claim, the hot spot is not specific to the enhanced greenhouse effect: Any surface warming (or cooling) would be expected to be magnified higher aloft, at least in the tropics. Lindzen says it as follows:

We know that the models are correct in this respect since the hot spot is simply a consequence of the fact that tropical temperatures approximately follow what is known as the moist adiabat. This is simply a consequence of the dominant role of moist convection in the tropics.

Read the rest of this entry »

The fallacy of the middle ground

August 5, 2013 by

There’s been quite some climate discussion in the Political Science section of the Guardian lately. Warren Pearce had an invited post in which he asked the rhetorical question “Are climate sceptics the real champions of the scientific method?

He makes some good observations about the dynamics of the public debate and the nature of skepticism (e.g. most contrarians don’t deny the basic physics underlying the greenhouse effect, but rather dispute the magnitude of warming that would result from an increased greenhouse effect). On the other hand, he misses the mark in other areas (e.g. he correctly describes how contrarians see themselves but doesn’t investigate how their argumentation really stacks up; often they are guilty of what they accuse mainstream science of).

My main beef with his piece though is his flawed argument of why a well-known contrarian blogger like Anthony Watts, according to Pearce, should be seen as someone who “seeks to uphold standards, through transparent and auditable scientific practice” and “a ‘mainstream’ sceptic who can challenge key areas of climate science without entering into pseudoscience”. Why this praise? Because Watts publicly disagreed with the fringe group Principia Scientific who deny the basic physics underlying the greenhouse effect (which was first established in the 19th century).

That is not a logical argument to make though: Regardless of what one may think of Watts, contrasting an extremist with someone who is even more extreme doesn’t make him mainstream. Regardless of what one thinks of Watts, contrasting someone who frequently flirts with pseudoscience with an all-out pseudo-science lover doesn’t free the former from any link with pseudo-science.

That is what I would call the fallacy of the middle ground.

Read the rest of this entry »


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