Archive for the ‘Climate science’ Category

Mike Hulme on the impacts of “climategate”

November 19, 2010

Mike Hulme has an editorial in the Guardian about “climategate”. It is a thoughtful piece, where he tries to take some distance from the events and see what impact they’ve had, focusing mostly on the positive:

I believe there have been major shifts in how climate science is conducted, how the climate debate is framed and how climate policy is being formed. And I believe “climategate” played a role in all three.

How climate science is conducted

As to the first, “climategate” may indeed have spurred the inevitable transition to more open source computer code and increased transparency. With the increased public and political interest, it is only natural to expect increased openness and transparency, to the extent possible and desired by scientists themselves (that last addition is not unimportant). The hope is that this could aid in the understanding of and respect for science, though that may be a little naive.

Efforts to re-examine the surface temperature record don’t signify a major shift in how climate science is conducted; they are replication exercises which, unsurprisingly, come to pretty much the same results as CRU or GISS do.  This seems merely a response to the misplaced decrease in trust in the temperature record. Overall, I don’t think the way climate science is conducted has changed dramatically as a result of this affair. It probably made a lot of scientists more afraid to speak out or more defensive when they do, neither of which is a good thing. That is the most significant impact as I see it.

How the climate debate is framed

Second, there has been a re-framing of climate change. The simple linear frame of “here’s the consensus science, now let’s make climate policy” has lost out to the more ambiguous frame: “What combination of contested political values, diverse human ideals and emergent scientific evidence can drive climate policy?”

The ‘ambiguous frame’ as Hulme calls it makes a lot of sense, and it always has. Does that signify a change? I don’t think so. Isn’t it common wisdom that there is more than just science that influences what policies are enacted? Consider e.g. this quote from the late Steve Schneider via mail to Andy Revkin:

To be risk averse is good policy in my VALUE SYSTEM — and we always must admit that how to take risks — with climate damages or costs of mitigation/adaptation — is not science but world views and risk aversion philosophy.

And as I wrote in a comment at the polarization and ideology thread:

One’s value system and circumstances influence how this risk is perceived. (…) How do you value the future vs the current (encapsulated in the discount rate), how is your sense of responsibility vs freedom, how do you weigh small probability – high impact events, those are the issues there, and they are inherently tied to one’s value system.


The events of the past year have finally buried the notion that scientific predictions about future climate change can be certain or precise enough to force global policy-making.

This is puzzling to me, as it seems to imply a straightforward relation between scientific certainty and policy making, whereas he just made the obviously correct point that there are other things that influence this relation. Update: I think I misinterpreted what Hulme said. Even if the science were 100% certain (which it will never be of course, by its very nature), it would still not ‘force’ a particular policy, exactly because contested values and human ideals will still enter the picture of decision making.

In effect, the big picture of what we know is clear, at least as to the ‘needed’ direction and thrust of policies (paraphrasing Herman Daly). But this direction and thrust apparently clashes with the values and ideals of a not unimportant segment of society.

The increased polarization between supporters of science and contrarians over the past year did probably contribute to putting this ‘ambiguous frame’ more into focus:

The meta-framing of climate change has therefore moved from being bi-polar – that either the scientific evidence is strong enough for action or else it is too weak for action – to being multi-polar – that narratives of climate change mobilise widely differing values which can’t be homogenised through appeals to science.

Very true.

How climate policy is being formed

Hulme’s third point, the lack of faith in reaching a global agreement on emission reductions, has much more to do with the failure of Copenhagen than with “climategate”, I think. During CoP 15 in Copenhagen, the overhyped expectations collided with the harsh reality of nations thinking mostly about their own short to medium term self interest. This classic tragedy of the commons on a global scale proved much too viscous to be easily solved.

Hulme argues that

with scientific uncertainties and complexities about the future proliferating (…) further policy fragmentation around climate change is inevitable.

Here again, Hulme seems to suggest that scientific uncertainty is the primary cause for the differences in opinion about the policy direction, in apparent contradiction to him stating earlier that contested values and ideals are also important. Is lack of scientific certainty really the limiting factor in reaching political agreement? I don’t think so. Policy fragmentation will be inevitable because people will continue to have different values and ideals and live in different circumstances, not because of scientific uncertainty (which concern the details rather than the big picture anyway).

Hulme continues:

But if such fragmentation reflects the plural, partial and provisional knowledge humans possess about the future then climate policy-making will better reflect reality. And that, I think, may be no bad thing.

Here I’ll quote a comment by Lcarey over at CaS, which captures my take quite well:

My conclusion is a little different.  IF the prevailing conclusions in a number of related fields within climate science are broadly correct, then humanity faces a global scale problem beyond the power of any given nation or small group of nations to address [except perhaps by geoengineering as a risky bandage-type strategy. BV].   In that case “fragmentation” translates into “pursuing our own short term interest, and not doing anything of great significance regarding CO2 emissions anytime soon”, which translates into “we’re screwed”

Judith Curry goes from building bridges to burning them

November 5, 2010

In her recent post, Judith Curry takes issue with the politicization of science. But rather than making a well reasoned argument backed up by evidence, her post comes across as a strong but largely unfounded allegation of widespread bias and dogmatism.

What to think of a passage like this:

Once the UNFCCC treaty was a done deal, the IPCC and its scientific conclusions were set on a track to become a self fulfilling prophecy. The entire framing of the IPCC was designed around identifying sufficient evidence so that the human-induced greenhouse warming could be declared unequivocal, and so providing the rationale for developing the political will to implement and enforce carbon stabilization targets.

This sounds like an accusation that the IPCC conclusions were predetermined before it even started assessing the science. That is a far reaching and very bold claim. All that Curry presents in favour of this claim is her narrative of a trio between UNFCCC, enviro advocay groups and scientists. The actual history and mandate of the IPCC however look quite different to me. Btw, that doesn’t mean that no valid criticism could be leveled against the IPCC, see e.g. Eric Steig’s comment at Judith’s or James Annan‘s frequent critiques.

And then:

When I refer to the IPCC dogma, it is the religious importance that the IPCC holds for this cadre of scientists; they will tolerate no dissent, and seek to trample and discredit anyone who challenges the IPCC.  Who are these priests of the IPCC?

Excuse me? Is this a respected scientist talking? Someone who is trying to build bridges between scientists and their critics? By calling respected scientists “high priests of the IPCC”?

This kind of accusatory framing, based on mere innuendo and speculation, is the main reason that she gets a lot of flack from other scientists. It increases, rather than decreases, the polarization, and it starts to overshadow those issues where she does (or at least did) make valid points.

I was actually quite sympathetic to Curry’s attempts at building bridges, and see a lot of truth in her criticism of circling the wagons. Keith Kloor, in an interesting post contrasting Judith’s post with Gavin’s at RC, aluded to an over-defensive reaction to criticism which is occurring both amongst those who portray themselves as heretics (such as Judith Curry) but also amongst mainstream scientists (quite understandably so, but probably counterproductive).

Her unfounded allegations are insulting for the whole profession. It increases the polarisation and doesn’t add to the building of bridges (perhaps a one-way bridge). And I’m saying this as someone who, on the “pro-AGW” bloggers side, was probably one of the most receptive to her ideas. I am sincere and anti-dogmatic and I take great issue with her painting a whole scientific field, at the edge of which I work myself, as quasi religious dogma.


Eduardo Zorita – not a big fan of the IPCC – agrees that “Curry’s reflections are too broad-brushed” and add to the polarization.

Some more stunning things from Curry, e.g. when she wrote

The media also bought into this [blind support of the IPCC against its critics], by eliminating balance in favor of the IPCC dogma.

This couldn’t be further from the truth. The media has actually suffered from the opposite, creating an image of false balance by giving minority viewpoints equal footing with the mainstream evidence based outlook.

She also aludes to there being no sign of a climate change problem in 1992 when she wrote about that time period:

Wait a minute, what climate change problem?

whereas she is quite aware of e.g. the National Academy of Science writing in 1979

A plethora of studies from diverse sources indicates a consensus that climate changes will result from man’s combustion of fossil fuels and changes in land use.

Update 2:

Coby Beck has a detailed critique of Curry’s “positive feedback loop” post.

Judith Curry has had quite a few follow up posts in the meantime, trying to explain where she’s coming from. The posts on “dogma” were not very helpful, but her recent post on “ideology” makes more sense. My reply to that post is here (I may try to make it into a post some day).

Update 3:


For it to be a bridge to some outside world, the bridge should remain grounded at the original place as well.

Your strong and broadbrush accusations towards your professional peers, and the lack of criticism towards empty talking points and conspiratorial thinking
make you lose that grounding imho. You’re pushing herself away it seems. It’s your choice of course, but I can’t square it with your stated objective.

I think the core of your argument as I see it (the need for scientists to be less defensive, less circling of the wagons, more introspection, more communication and collaboration with “outsiders”, taking criticism seriously, etc) is important and valid. But the way you go about airing it, with broadbrush accusations towards mainstream science/ists (RC en the IPCC process are squarely in the mainstream), give the impression of a one way bridge, where as you walk along you burn the bridge behind you.

See as an example how different (e.g. constructive rather than destructive) John Nielsen-Gammon voices his criticism. Granted, your criticisms may be stronger, but the way they come across, I tend to think that an increasing number of climate related scientists will be put off by it, at the same time as an increasing number of true skeptics, pseudo-skeptics and conspiracy theorists will cheer you on.

In effect, your accusatory framing comes across as very tribalist.

Andrew Dessler debating Richard Lindzen

October 20, 2010

Eli Rabett covers the debate between Andrew Dessler and Richard Lindzen (video embedded at the link). Purportedly the former smoked the latter, though I haven’t watched the whole thing yet so can’t vouch for that.

Quoting Eli quoting Andy:

It all fits together (…). The key thing to look at is look for coherence, look for lots of evidence supporting a point and you will clearly see why scientists are convinced that the mainstream view of climate science is right.

The real question I want to address here is this question of how much does carbon dioxide warm the climate [not whether it does at all]. (…) We are going to use a standard measure which is how much warming would occur if we doubled carbon dioxide, so we are going to go through the math and do a very simple calculation that indicates that we might be screwed.

IPCC history and mandate

October 1, 2010

The purpose of the IPCC was to assess the state of knowledge on the various aspects of climate change including science, environmental and socio-economic impacts and response strategies.

I.e. it was meant to report on and asses the scientific knowledge. This includes the question of how much evidence and (as a result) how much agreement amongst experts (consensus) there is for human induced climate change.

Some science historians point to other important aspects of IPCC’s history. The National Academy of Sciences wrote in 1979:

A plethora of studies from diverse sources indicates a consensus that climate changes will result from man’s combustion of fossil fuels and changes in land use.

Oreskes shows that the IPCC was set up in response to the emerging consensus in the 70’s/80’s that global warming due to GHG emissions would likely become a problem.

Spencer Weart writes:

The concern [about impending climate change] gave rise to the IPCC.

And also points to the Reagan administration being in favor of the clumsy IPCC approach, hoping that it would downplay the scientists’ fears.

When pointing to scientists who disagree with the IPCC consensus, it is important to note that people can agree in basically two directions. The survey by Brown, Pielke Sr and Annan for example shows this to be an approximate bell curve: Most (45-50%) of the respondents (scientists) more or less agree with the main thrust, and sizeable minorities (15-20%) think that IPCC overstated or understated its case. I discussed this survey and the broader question of why the consensus matters before. And I probably will pick this up again soon.

Scientifically, the more uncertain areas are the most interesting. However, if I look at the political decision making in terms of emission reductions and knowledge of the big picture (and the length of time that we’ve known about this big picture, albeit in gradually more certain terms), I can’t but conclude that the politics is hopelessly lagging behind the scientific knowledge in taking this problem seriously. (see e.g. my Dutch post “tijd voor de politiek om wetenschap serieuzer te nemen”.) Of course I’m aware that there’s more that informs politics than just the science, but still, there seems to be an uncomfortably big disconnect there. Stark warnings from science are ignored at our peril.

At this point in time, the uncertainties are pretty much irrelevant for policymaking, because any realistic change in the uncertain details is not going to affect the main trust of what we know, and thus the policy response that people may favour. For the long term, of course we need to finetune our knowledge, so research is still needed. (Hey, I’m a scientist, so I kind of have to say that, right?)

As Herman Daly said:

“Focusing on them [the big picture of what we know] creates a world of relative certainty, at least as to the thrust and direction of policy.” On the other hand, focusing on the more uncertain rates and valuations creates “a world of such enormous uncertainty and complexity as to paralyze policy”.

Perhaps that’s indeed what’s happening now, also cf. Judith’s uncertainty monster and complexity monster.

“To make the point more simply, if you jump out of an airplane you need a crude parachute more than an accurate altimeter.”

Funny how Daly and Curry both address the huge issues of uncertainty and complexity and arrive at diametrically opposed strategies of dealing with them. In terms of public communication, I’m with Daly.

From the principles governing IPCC work:

The role of the IPCC is to assess on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation.

IPCC reports should be neutral with respect to policy, although they may need to deal objectively with scientific, technical and socio-economic factors relevant to the application of particular policies.

Funnily enough, a commenter at Judith’s, Paul in Sweden, took this as proof of a “blatantly biased agenda”. Which is a little strange in light of the history of climate science and of the IPCC as mentioned above. Its mandate is a consequence of the scientific evidence for human induced climate change having become increasingly strong and societally relevant. It doesn’t state what the conclusion ought to be –it has to follow the science-, but of course it states what it’s supposed to assess.

Judith Curry also seems to suggest that the IPCC reports are working towards a predetermined conclusion, when she claims that they are akin to a legal brief (meant to persuade). If true, that should be reflected by large differences between the scientific evidence and the IPCC reports, and between scientists’ opinions and the IPCC reports.  I have not seen evidence of either.

Tom Curtis made some very thoughtful comments on the consensus thread at Judith’s, e.g.

In other words, the IPCC was tasked with reporting the consensus view of the science, were such a consensus existed; and to explain and report the differing opinions where no such consensus existed. Whether they have done that is not best judged by whether they have explained and included the opinions of every crackpot fringe group with an axe to grind on global warming; nor even those of every climatologist, no matter how small a number might support their views. Rather, they are to be judged by the agreement between the IPCC reports and the known consensus and divergences of scientific opinion.

Fortunately, we have available several anonymous surveys of the scientists opinions, which show conclusively that the IPCC reports fairly represent the consensus of relevant scientists on those topics on which it reports. (…)

The purpose of IPCC is to provided as succinctly as possible the best possible scientific advice for policy deciders to operate on. If they were required to consider all and every idea on climate change that circulates on the blogosphere; then the resulting document would be to large, and to ill organised to be usefull as a guide to policy.

Nevermind that the politicans still wouldn’t have a clue as to what is more likely true. The science has to be assessed and weighted; that is what makes the IPCC process useful. There already is another outlet for every crackpot idea out there (NIPCC report); it doesn’t need to be done by the IPCC as well.

To quote the Dutch newspaper “Volkskrant” again:

its work has political implications, but that that doesn’t mean that it’s engaged in doing politics.

And since I discussed history as well, see also my first blog post where I described the IPCC process. I don’t think anyone has read it yet, so I’d be much obliged. And while doing self-promotion, I kind a like this oldie featuring Fred Singer.

Judith Curry on anthropogenic versus natural causes of global warming

September 20, 2010

As most will know by now, Judith Curry has started her own blog, Climate Etc. In a recent post entitled “doubt” she said some things that highly surprised me. Basically, she claims equal evidence for anthropogenic forcing and natural variability being responsible for “most of the observed increase in global average temperatures since the mid-20th century”:

As an example, my personal weights for the Italian flag are:

1. white 40% [uncertainty and unknowns]

2. green 30%, [evidence for anthropogenic forcing]

3. red 30%. [evidence against anthropogenic forcing]

Before posting this, I had an email conversation with Judith Curry about these issues (so as to minimize any misunderstanding on my part). She wrote back (reprinted with permission):

I think you are misunderstanding what the IPCC actually says.  The statement says MOST (>50%) of the warming can be attributed to  anthropogenic, with an confidence of very likely (>90%).    My balance of 50-50 is a hair outside the IPCC range (which could include 51-49), and 1% difference is in the noise here.   Most can imply 51% or 90%.   I will be discussing the issue of attribution at length in a future point.  But my main point in the doubt post is the size of the white area, which is bigger than 5-10% IMO.

So she would translate the IPCC statement in the Italian flag style as anywhere between

white: 10 -1

green: 46 – 89

red: 44 – 10

Her own estimate is not that far off (in terms of the ratio between green and red) from the most conservative IPCC statement (where “most” means “just a bit more than half”), except having a much greater estimate of the uncertainty (which is her main point). So she seems to interpret red and green as portions attributable to anthropogenic and natural forcing, whereas initially I had interpreted them as evidence for the statement at hand versus evidence against. Both makes sense, but both are different. Also, one could claim that the IPCC statement encapsulates the uncertainty in the fairly wide “most of the warming”, i.e. it could still span a wide range, allowing for plenty of uncertainty. Similar as say, the weather in a week’s time is very uncertain, but I can still say that it’s very likely to be in between zero and thirty degrees C (being late september in Holland). These different interpretations make me doubt the usefulness of the Italian flag symbol to aid in clarifying (dis-)agreements.

Judith also claims equal evidence / equal portions of attribution for her “litmus test question”:

Will the climate of the 21st century will be dominated by anthropogenic warming (green) or natural variability (solar, volcanoes, natural internal oscillations)?

which is the question with the greatest policy relevance, IMO.  My scores on this one are

green 25%

white 50%,

red 25%.

This is astounding. I interpret this as claiming equal evidence pointing to natural variability being dominant over the next 90 years as compared to anthropogenic forcing. Or alternatively, an equal portion of 21st century climate change being attributable to human induced warming as to natural variability.

I’ve read quite a few “skeptical” papers that attempt to blame the warming on natural processes, and even if you’d take them as face value (even though in most cases they haven’t stood up to scrutiny), their collective body of evidence is a molehill compared to the mountain of evidence pointing to the dominance of anthropogenic forcing.

In a comment, Judith points to a blog post at Skeptical Science, with graphs of several natural forcings (solar) and cycles (PDO, ENSO) for the past 25-30 years. They exerted a slight cooling effect over this period. In contrast, CO2 exerted a strong warming effect, and indeed, the temperature has gone up. That hardly qualifies as equal amounts of evidence pointing to the warming being natural versus anthropogenic.

For future warming, her pronouncement is even stranger. In all plausible scenario’s, greenhouse gas concentrations will continue to rise for at least another few decades; in a business as usual scenario for many more to come. What natural forcing or variability could plausibly rival this relentlessly rising anthropogenic forcing in magnitude? Is there evidence at all for that being plausible? If so, is that evidence really as large as the evidence showing that greenhouse gas forcing will exceed the likely bounds of natural variability (if it hasn’t already)?

Take a look at how the global average temperature has varied over the past 130 years (yearly averages with 11 year running mean in bold):

An indication of unforced natural variability is given by the year to year variation, amounting to 0.1 to 0.2 deg C on a yearly basis. As the Skeptical Science article shows, natural forcings can not explain the most recent warming, because they don’t exhibit a trend of the needed direction or magnitude.

Now let’s stipulate that it’s all due to longer term natural variation (as opposed to a forcing) of an unspecified kind. What would that mean for the planetary energy balance? If internal variations would have been responsible for most of the planetary warming, the earth would be emitting more energy to outer space than it receives, resulting in a negative radiative imbalance at the top of the atmosphere (or the energy would have to come from other parts of the earth’s system).

Neither is the case. It’s actually opposite: There is a positive radiation imbalance and other reservoirs (e.g. oceanscryosphere) are also gaining more energy.

And then we haven’t even looked into the future yet. I recently posted this graph of two scenario’s that plausibly bracket a business as usual trajectory (red) and a stringent emission reduction trajectory (blue). The measured temperature increase up to now (which according to most scientists is strongly impacted by anthropogenic emissions) is given by the black line.

Judith’s estimates for the 21st century come down to a chance of warming of 0.25 + 0.75/2 = 0.625 versus a chance of cooling of 0.375, assuming natural factors having a 50% chance of either warming or cooling. So she deems the chance of warming to be roughly twice that of cooling, presumably even in a BAU scenario. Too bad that’s too long of a timeframe to place a climate bet on.

Look at how much the red -and even the blue- projections will likely deviate from the recent temperatures. I sure hope that there will be some magical counteracting cooling effect, but I haven’t seen any plausible evidence for such.

Postscript: From our email conversation, I understand her point of view better than before. But unlike the statement about the 20th century warming, which is not as far off from the IPCC as I had initially thought (except for the amount of uncertainty), her statement about the projected 21st century warming is hard for me to square with the mainstream scientific view, for which there is lots of evidence.

Extreme weather and climate change

August 18, 2010

It is an ill-posed question whether the 2003 heatwave was caused, in a simple deterministic sense, by a modification of the external influences on climate—for example, increasing concentrations of greenhouse gases in the atmosphere—because almost any such weather event might have occurred by chance in an unmodified climate. However, it is possible to estimate by how much human activities may have increased the risk of the occurrence of such a heatwave.

This is from a 2004 article in Nature about the European heatwave of 2003. The same can probably be said about the Russian heatwave of 2010. Arguing about whether this was ‘caused’ by AGW doesn’t make sense, unless you clarify carefully what you really mean.

A single weather event can not be attributed one-to-one to an external forcing of the climate. But the chance of occurrence can. Therefore it is in principle possible to say something about the relative likelihood of a certain extreme event in an unperturbed climate versus that in a human-perturbed climate. Or, to put it differently, to assign a certain portion of the blame/causality to the external forcing.

The return period for European heatwaves: Human influence has increased the chance of occurrence 9 fold. Figure from a 2008 presentation by Myles Allen (slide nr 24).

Weather is not climate. But of course they are related. In fact, climate change is a consequence of the weather changing over time. Due to changes in the planetary energy balance the chance of certain weather conditions changes. Over time this becomes apparent as a change in the mean weather: The climate has then observably changed. You cannot have climate change without changes in the weather.

Nielsen-Gammon has a good article about how to deal with these attribution issues related to single weather events. (h/t Judith Curry over at Kloor’s)

In between these two extremes, where AGW in a sense causes everything and AGW changes the probabilities but doesn’t in a sense cause anything in particular, there are, I think, two possibilities for ways in which we can assign a portion of the blame to AGW if appropriate.

The first way is to consider the direct effect of AGW on the mean state of the atmosphere, and consider that change to the mean state as AGW’s contribution to individual weather events. I’ll call this the “additive effect” approach. (…)

So, for example, temperatures in large parts of Russia are averaging 6 C or more above normal. At this point, climate change (from all anthropogenic causes), according to best estimates, has produced about 1 C of warming in the area. So it would be fair to say that man has turned what would have been a 5 C heat wave into a 6 C heat wave. Climate change has added one degree to the heat wave.

This sounds like a small impact, but it’s not appropriate to attribute 1/6 of the impacts to anthropogenic climate effects. Deaths, fires, and the like increase nonlinearly with the severity of a heat wave, so anthropogenic effects have made this heat wave lots more than 20% more severe than it would have been otherwise.

(This is meant to be an illustration, not a rigorously quantitative attribution.)

The second way is to consider the estimated effect of AGW on the probability of extreme events. I’ll call this the “probabilistic approach”. (…)

For extreme events, we want to know how often a certain threshold is crossed. (…)

So, to correctly say that an individual event was likely caused by AGW, its probability of occurrence would need to have increased, because of AGW alone, by a factor of 3 or more over pre-AGW conditions.

(bold in original; “likely” in the IPCC sense refers to 67% to 90% chance, hence the factor of 3)

Michael Tobis puts the question as follows:

“Is the average time between persistent anomalies on this scale anywhere on earth in the undisturbed holocene climate much greater than a human lifetime?” In other words, is this so weird we would NEVER expect to see it at all?

There are two approaches to answering this question. One is statistical (mathematical), and the other is integrative (based on experience and expertise rather than number-crunching).

He also summarized his position nicely in a comment at Kloor’s:

Stopping at “attribution of causality of individual events  is impossible” is not strong enough for the recent astonishing situation in Asia. “We are absolutely certain this couldn’t have happened in an undisrupted atmosphere” is too strong (…)

Why claim it is so unusual? Three reasons 1) this is an uncommonly stable and long-lived pattern (those are not good) 2) this is an uncommonly intense pattern, dipping all the way to the monsoon zone and fraternizing with the monsoon, to Pakistan’s great detriment and 3) the really big events tend not be in summer and not to be centered on hot spots but on cold spots. In other words, this blocking event has features dramatically different form other ones we have seen.

From ClimateCentral:

While there’s overwhelming observational evidence showing that humans are affecting climate, this evidence comes from long-term trends, rather than individual events.

Extreme events are related to climate change, however: the odds of them happening are much greater with climate change. (…)

We can estimate probabilities, but rarely can it be asserted with 100 percent confidence that there is a causal relationship between variables.

Tom Yulsman has an interesting article based on an interview with Peter Stott. What struck me though was Steve Bloom’s comment, comparing the manner in which doctors talk about the health risks of smoking versus how climate scientists talk about the climatological risks of greenhouse gas emissions. See also this pointy comment by SecularAnimist. Doctors tend to be much more upfront about the risks than climate scientists are (see also my previous post).

Assessing an IPCC assessment. An analysis of statements on projected regional impacts in the 2007 report

July 5, 2010

PBL Netherlands Environmental Assessment Agency has found no errors that would undermine the main conclusions in the 2007 report of the Intergovernmental Panel on Climate Change (IPCC) on possible future regional impacts of climate change. However, in some instances the foundations for the summary statements should have been made more transparent. The PBL believes that the IPCC should invest more in quality control in order to prevent mistakes and shortcomings, to the extent possible.

And from the presentation slides, regarding the focus of this assessment:

Media reported on errors in regional chapters of the Working Group II Report (impacts. adaptation, and vulnerability to climate change)
Investigation focused on 8 regional chapters in Working Group II Report, and on carry-over in summary of the IPCC Synthesis Report
Reports Working Groups I and III not investigated

Media reported on errors in regional chapters of the Working Group II Report (impacts. adaptation, and vulnerability to climate change)􀂃Investigation focused on 8 regional chapters in Working Group II Report, and on carry-over in summary of the IPCC Synthesis Report􀂃Reports Working Groups I and III not investigated

Reflections on climate discussions in the blogosphere between Keith, Lucia and me: The spectrum of opinions, uncertainty, risk and inertia

June 11, 2010

Keith Kloor has a post up that is an almost literal transcription of a conversation we had between him, myself and Lucia.

It’s a good initiative I find, to attempt to ‘bridge the climate divide’, as his post is titled. It’s an important theme for me as well. I’ve tried to find common ground with others before, e.g. Tom Fuller and Roger Pielke Jr.  Not that I see such a huge divide between Lucia and myself at all, but that’s also what makes such a conversation both possible, useful and enjoyable. A conversation between more extreme or more excitable voices on either side may quickly become an exercise in mudslinging; there has to be some common ground in order to have a conversation.

The crux of what I had to say is this (quoting myself):

So you have a large amount of inertia in the energy system, in the carbon cycle and in the climate system, which means if you start taking actions, it’s decades into the future until they start taking effect.

If you combine that inertia in those different systems, with uncertainty of the precise effect, and with some knowledge that it could go pretty wrong with a business as usual scenario, then you have to take proactive steps, and that’s where the urgency comes from.

In my view, it’s similar to a chainsmoker who gets told by a physician, “hey, you should really be careful, you should stop smoking if you care about your heath.” And the person says, “hey I can still bike to the town and I feel fine and my grandmother lived until she was 96 and died in a car accident.”

You can postpone dealing with smoking until you’re in the intensive care unit. But that’s a little late. That’s the line of argument in which I see the urgency of climate global warming.

I plan to go into these issues in more detail at some point.

Thanks Keith and Lucia!

Lucia’s report is here. She makes the interesting observation that

It seemed that Bart and I may disagree less when on Skype than when posting comments at Roger Pielke Jr.’s blog. That’s an interesting thing in and off itself.

Though perhaps we have slightly different recollections of our (few) discussions at Roger’s. We never were very antagonistic as far I recall, though on the impersonal internet it’s always easier (tempting even?) to be more antagonistic than one is in “real” life (insofar as Skype is real and not internet; ah well, you get the point).

Scott Denning to ICCC Heartland ‘conference’ gathering: “Be skeptical… be very skeptical!”

May 21, 2010

An excellent presentation was given by atmospheric scientist Scott Denning at the Heartland Institute gathering (ICCC 2010), amidst much ‘skeptical’ talk, which is the expected staple over there (h/t Michael Tobis). Both to Denning’s and Heartland’s credit, he was invited to speak there and his talk was apparently well received. How the audience will resolve their inevitable cognitive dissonance remains to be seen.

He makes a number of important points, which are especially apt for a ‘skeptical’ audience:

– The expectation of global warming to result from greenhouse gases is based on common sense and basic physics:

[It is] based on the idea that when we add energy to the surface, it will warm up

Be skeptical of the claim that this extra energy will somehow magically be negated.

Climate sensitivity is around 3 degree for a doubling of CO2 concentrations. This is based on e.g. observations from the Last Glacial Maximum, when the climate forcing was 4.1 W/m2 from greenhouse gases and 3.4 W/m2 from the difference in surface albedo (snow and ice are brighter, and thus more reflective, than water and land surfaces), and the temperature difference with the interglacial that followed was about 6 degrees C.

“No climate models required … just based on observations

(modern calculations agree … coincidence?)”

About a quarter of today’s emissions will stay in the air [semi-] permanently! So when we reduce or stop the burning of fossil fuel, things will not go back to normal for a very long time.

– Historically, 3 degrees C warming is a big deal (e.g. for sea level rise).

– And on how (not) to frame the mitigation challenge:

Then making the obvious point that society didn’t go broke building that very system. To the contrary…

The worst media myth of all: Without the subsidy of cheap fossil energy, civilization will crumble!

Be skeptical… be very skeptical!

He’s not afraid of sarcasm:

You’d think those un-American naysayers had never heard of capitalism …

of the magic of markets …

of the creative genius of a free people!

… or to call a spade a spade:

Alarmist politicians and pundits say:

“(…) If we stop burning coal we’ll freeze in the dark!”


He very effectively changed the frame of the debate:

– The science is about common sense and basic physics

– Who is being ‘alarmist’?

– Being so ‘alarmist’ about the consequences of mitigation efforts is antithetical to having faith in the ‘magic of markets’, entrepeneurship and the power of innovation.

Come to think of it, it is quite surprising that his talk was well received, as there were quite a few digs towards the common way of thinking of undoubtedly many members of the audience. I guess it was delivered with style, respect and humor, and towards the end, he provides his audience with both a mirror and a carrot. There are communications lessons to be learned here. Also, Heartland was clearly happy to have a mainstream scientist present at their party. After all, they crave being taken seriously. The real question however is, did it sink in?

A point of critique could be that he glossed over the mitigation challenge a bit easily, apparently trusting that “the magic of markets” will take care of new energy technologies being invented and implemented. Such a frame may encourage a ‘wait and see’ approach, which I deem risky. I guess a bit of skepticism is at its place whether it will happen so effortless. A lot may depend on how long we keep postponing meaningful emission reductions.

Those who most strongly oppose government intervention would be wise to call for strong early action to avoid really stringent measures becoming necessary later on.

Open letter of US NAS members on climate change and the integrity of science

May 10, 2010

The open letter of US National Academy of Science members is worth reading. After initially being behind a paywall (rather at odds with the ‘openness’ of the letter…), it is now freely available at Science.

I agree with the gist, well exemplified by the opening paragraph:

We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular. All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything. When someone says that society should wait until scientists are absolutely certain before taking any action, it is the same as saying society should never take action. For a problem as potentially catastrophic as climate change, taking no action poses a dangerous risk for our planet.

Scientific conclusions derive from an understanding of basic laws supported by laboratory experiments, observations of nature, and mathematical and computer modeling. Like all human beings, scientists make mistakes, but the scientific process is designed to find and correct them. This process is inherently adversarial—scientists build reputations and gain recognition not only for supporting conventional wisdom, but even more so for demonstrating that the scientific consensus is wrong and that there is a better explanation.

Indeed, the scientific process is meant to ascertain that, despite scientists being human with their individual characters and inherent flaws, the collective outcome is as good a representation of reality as possible at the time. And science (including climate science) has proven to be rather good at that.

But there is nothing remotely identified in the recent events that changes the fundamental conclusions about climate change:

(i) The planet is warming due to increased concentrations of heat-trapping gases in our atmosphere. A snowy winter in Washington does not alter this fact.

(ii) Most of the increase in the concentration of these gases over the last century is due to human activities, especially the burning of fossil fuels and deforestation.

(iii) Natural causes always play a role in changing Earth’s climate, but are now being overwhelmed by human-induced changes.

(iv) Warming the planet will cause many other climatic patterns to change at speeds unprecedented in modern times, including increasing rates of sea-level rise and alterations in the hydrologic cycle. Rising concentrations of carbon dioxide are making the oceans more acidic.

(v) The combination of these complex climate changes threatens coastal communities and cities, our food and water supplies, marine and freshwater ecosystems, forests, high mountain environments, and far more.

However, as Revkin notes:

The open letter letter has a defensive tone that hasn’t served scientists particularly well in the past, but is understandable given the pressures that have been mounting on this field of inquiry.”

I agree with both parts of that assessment.

Also noteworthy is the accompanying editorial by a deputy editor of the journal Science, which has a distinctly different tone to it (not dissimilar to Judith Curry’s statements):

We thus must move beyond polarizing arguments in ways that strengthen this joint commitment. The scientific community must recognize that the recent attacks stem in part from its culture and scientists’ behavior. In turn, it is time to focus on the main problem: The IPCC reports have underestimated the pace of climate change while overestimating societies’ abilities to curb greenhouse gas emissions.

I’d say that the main problem now is, that given our current understanding of climate change, how are we going to respond? There is no such thing as ‘no response’. Any action (including business as usual) is a response, and it better be decided on rationally and based on all the available evidence. That’s the way I look at it.

He also calls for more effort (and commensurate funding) towards data curation, handling and infrastructure. Perhaps that’s something we could all agree on, and perhaps those most critical of the current data handling practices could support such calls for more funding of these basic, though necessary efforts.

He ends with a good quote from Carl Sagan, which is especially apt today:

“We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.” “This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.”

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