Thursday, December 21, 2006

Nature ends public peer-review trial

According to this story, Nature is scrapping its attempt to open up the peer review system.

As the article says,
In the Nature experiment, authors whose manuscripts were selected for traditional peer review could also opt to have them simultaneously posted on the Internet for feedback by rank-and-file scientists. Journal editors then weighed both sides when deciding whether a paper gets published.

The experiment generated high online traffic, about 5,600 page views a week, according to Nature. But it was ultimately canceled because few authors participated and many of the online comments were nothing more than "nice work."

My experience with open peer review (through the journal Atmospheric Chemistry and Physics) is similar. While it seems like a good idea, few articles get any public comments. I suspect this is true for a few reasons. First, it can be dangerous to make negative comments without anonymity (and on ACP comments must be attributed) --- which is why most journals implement anonymous reviewers. Second, it takes a lot of time to write a comment, and most people are simply too busy. Another reason the Nature experiment failed was that they did a terrible job publicizing it.

As a dedicated blogger, I see great value in an open comment system and I suspect that some kind of open system will eventually be adopted. However, I don't think any journal has yet stumbled upon the winning model.

Wednesday, November 22, 2006

The CO2-temperature correlation

Hello, gentle readers. I'm back --- sort of. I've decided that I'm going to post on this blog links to my blog entries on grist.

I'm doing this because there's no way to get an RSS feed from grist for just my articles, and as a result it's easy to miss my posts. You can get an RSS feed from this page, and that will alert you to my new grist posts.

Also, some former readers have expressed some reticence about posting on grist. Feel free to post comments here or on grist.

My most recent post is on the well-known CO2-temperature correlation. You can find it here.

Tuesday, October 24, 2006

I'm going to Disney World!

OK, not really. Turns out I'm afraid of people in giant mouse suits.

But what IS happening is that this blog is moving to Check out my blog page. Other than the host, everything else about the blog should remain the same. I hope you head over there and keep reading my stuff!

This web site will remain up, but I don't plan on posting here anymore.

[NOTE added in proof: the site requires an e-mail address to sign up. Here's a tip for those who don't want to give out their real e-mail: use the e-mail avoider service. Check out their FAQ here. It's a great and free service that I use all the time.]

Sunday, October 22, 2006

The "house of cards" analogy

In a comment to the "puzzle analogy" post, Bill Chameides points out an alternative analogy that climate skeptics like to push:
Science skeptics often try to undercut established science (be it global warming or something else) by portraying the knowledge-base as a house of cards. They hope by identifying one weak link, they can bring the whole house down (i.e., create the illusion of uncertainty in the entire subject.)
Examples of this strategy are easy to find. After the NRC hockey stick report concluded that we really don't know what the temperature was 1000 years ago, many skeptics used this to argue that this repudiated all climate science. This is, of course, nonsense. Important conclusions in science are all subject to multiple tests and verifications, and scientists do not accept a conclusion until it has been multiply verified. As Bill concluded:
In fact, most science is like a jigsaw - lots of interlocking pieces based on multiple, independent lines of inquiry. Even if you take away one piece, the picture is still apparent.

Friday, October 20, 2006

Canada's new greenhouse gas targets

A recent news article described a proposed greenhouse gas target for Canada:
Canada will aim to reduce its greenhouse gas emissions that cause global warming by 45-65 percent by 2050, ... The bill introduced Thursday in the House of Commons would also apply intensity-based targets until 2020, allowing emissions to continue to rise until then.
There're actually a lot of advantages of this target over something like Kyoto. First, it sets a definite long-term target, which Kyoto does not. This provides a more stable environment for people and companies to make investments in emissions reducing technology. Second, it allows emissions to grow in the near term, i.e., does not require sharp near-term cuts in emissions, as Kyoto does. Most economists agree that allowing some near-term growth followed by steeper cuts later provides the lowest cost trajectory to get to your preferred emissions level.

The downside of a longer term target is that it can be used as a stalling tactic if the administration really doesn't want to do anything about the problem. However, one need not wait long to find out if that's the case. While some emissions growth can be tolerated near-term, deviations from business-as-usual need to occur within a few years to hit the target in 2050 at minimum cost. Thus, if Canada is serious about this, we need to see some near-term actions relatively soon.

Finally, the target is not quite ambitious enough. In order to stabilize the climate at around 550 ppmv (i.e., double pre-industrial CO2), we need to reduce world emissions to about 2 GtC/yr, about 80% less than we're emittiong today. Their target, 45-65% reductions, would not be sufficient to do this if applied to the entire world.

Tuesday, October 17, 2006

Values in the climate change debate

An interesting editorial can be found here. One particularly interesting point they make is about the moral dimension to the problem:
Without mitigation, rising global temperatures are expected to cause ferocious hurricanes, tornadoes and floods; spawn heat waves, drought and famine; and prompt the spread of disease-carrying insects.

Middle- and upper-class families will hop in their cars to seek refuge from storms. They'll vaccinate their children and find good health care. They'll buy air conditioners. The poor, lacking resources to adapt, will disproportionately suffer and die.

Global warming isn't just an environmental debate. It's also about social and racial justice.
If you read the various blogs, many opposed to action will make the argument that addressing AGW is too economically damaging. My experience is that many of these people are so married to the economics of the problem that they don't even recognize that there exist different ways to look at the problem. In fact, the decision to take a cost-benefit view is itself a moral choices --- and one that is debatable.

My view is that some balance needs to be achieved: costs and benefits need to be considered, but so do the issues of social justice and fairness. Only by doing this can we obtain a socially and economically optimal solution to this problem.

Monday, October 16, 2006

The puzzle analogy

I recently heard a good analogy about climate science from Bill Chameides, chief scientist for Environmental Defense.

The state of science of climate change today is like a partially completed jigsaw puzzle. There are lots of pieces in place --- things we know quite well (like the water vapor feedback) --- and lots of areas where there are no pieces --- things we don't know particularly well (like cloud feedbacks). The point here is that you don't have to have every piece in place in order to know what the picture looks like. Consider the image above. While many pieces are missing, one can easily observe that it's an image of fruit.

Climate science is like that. While there's a lot we don't know, the big picture is still clear. We know the climate is warming, humans are contributing, and there's a risk of significant warming over the next century. The missing pieces don't change any of that.

The "uncertainty" argument would have you believe that, if even one piece is not in place, that we have no idea what the big picture is. That's simply not true.

Thursday, October 12, 2006

Climate models vs weather models

You can find a lot of discussion on the net with arguments like:
If we cannot predict the weather next week, how can we predict the climate over the next century?
While this sounds like a reasonable argument, there are in fact good reasons to accept 100-year climate forecasts even though we cannot predict the weather more than a few days out.

Predicting the weather is hard because you have to get the exact details of a weather system right. If your prediction of a storm track is 100 km off, then a giant snowstorm predicted to bury a city might fall harmlessly offshore. If your temperature is 3 deg C off, then what you predicted as rain turns into snow. If your initial conditions are off, then precipitation predicted to fall during rush hour falls at midnight. All of these things mean that you've blown the forecast, and people will mumble about how weather forecasters don't know what they're doing.

For the climate, these things generally don't matter. What matters is that, in the long run, one gets the statistics of the weather right. If one storm in a climate model is 100 km too far East, that won't matter if the long-term statistics of the storm track is right. This is quite a different problem than predicting the EXACT evolution of a single atmospheric disturbance.

One simple way to think about the difference in predicting weather and climate is to think about rolling a six-sided die. Predicting the weather is like predicting what the next roll will be. Predicting the cliamte is like predicting what the average and standard deviation of 1000 rolls will be. The ability to predict the statistics of the next 1000 rolls does not hinge on the ability to predict the next roll. Thus, one should not dismiss climate forecasts simply because weather forecasts are only good for a few days.

One should not take from this that climate modeling is easier than weather forecasting. There are several aspects of the problem that make climate modeling more difficult than weather forecasting: climate models need to also predict the evolution of long time-constant domains like the oceans, cryosphere, and biosphere. Weather models don't have to worry about these things because oceans conditions, etc. don't change over a few weeks. Climate models also use uncertain predictions of future emissions, from which the atmospheric concentration of CO2 and other greenhouse gases will be determined.

Another statement you hear is that:
Because climate models do not predict next year's climate, why should you believe a prediction in 100 years?
Here's why: short-term forecasts (e.g., over the next few years) require accurate simulation of the magnitude and phase of short-term climate variability like El Nino. Over much longer time scales, however, one does not need to accurately simulate these short-term climate variability. I discussed that here. The upshot is again that one should not dismiss the long-term climate forecasts because short-term forecasts are problematic.

Tuesday, October 10, 2006

Report from the G8 meeting on climate

An interesting article about the recent G8 meeting on climate can be found here.

A few quotes of note:
Several said they had never known such a positive atmosphere. Nobody doubted the reality of climate science anymore.
This continues a trend that I've noticed recently. Those opposed to action now rarely attack the science. Their arguments tend to be more diffuse, with more of a focus on economic and fairness issues.

The Under-Secretary of State for Global Affairs, Paula Dobriansky, told the BBC that the US was now acting urgently to tackle greenhouse gases - then later admitted that the country's emissions would continue to rise.
The statement that the U.S. is working hard on climate change is as accurate as the statements "We will be greeted as liberators" and "The insurgency is in it's last throes". The U.S. is, of course, doing essentially nothing.

So, for all the positive mood of the meeting in this spectacular northern Mexican city, surrounded by towering limestone mountains, it is hard to be optimistic.

The UK Environment Secretary David Miliband said there had been real and practical progress but warned that the pace of action had to be much faster or CO2 emissions by 2050 would be 137% higher than in 2003.

"Business as usual", he said, was not an option.

One delegate told me he thought the pace of political ambition on emissions was so slow that we had a 1,000-1 chance of avoiding dangerous climate change.

He later sent me a text message to assert that he had been overly pessimistic. The odds, he said, were only 100-1.

The chances were bad, he said, but it was still worth fighting on.
I'm not as pessimistic as this delegate, but I agree that we are at present far away from any workable program to stabilize atmospheric CO2. Perhaps the 2009 inauguration of a new President will change that.

Sunday, October 08, 2006

The build-up of CO2 in our atmosphere will be good!

A common argument you hear goes like this:
because increased CO2 will lead to increased plant growth, the build-up of CO2 must therefore be a net benefit rather than a net harm to our society
Does this type of argument make sense? To understand why it doesn't, realize that in any environmental disaster, some groups always benefit. Consider the destruction of New Orleans by Katrina. Few people consider this event to be a net benefit to our society. However, it is easy to pick out small groups that greatly benefitted from it. The owners of demolition companies, construction companies, construction material companies, etc., are all making money hand over fist.

Thus, one could make the argument:
Katrina's destruction of New Orleans was a highly beneficial event because it greatly stimulated the construction industry on the Gulf Coast.
This is, of course, extremely misleading and most people would agree is wrong. While some benefitted from the destruction of New Orleans, the net result, considering all harms and benefits, was clearly negative.

So when people argue that climate change must be good because plants grow better at higher CO2, think about the Katrina example. Plants might indeed do better(*), but that tells us nothing about all of the other harms and benefits. As I discussed in a previous post:
Clearly, some people will benefit from warming, while others will suffer. There are a lot of dimensions to this (economic, moral, etc.), but I'll just give the broadest answer. For small warming (e.g., 1 deg C over the next 100 years), current thinking is that harms and benefits are largely comparable, although it is estimated that harms still outweigh the benefits. As the warming increases, the harms get much bigger, and begin dominating over benefits somewhere around 2-3 deg C of warming. That's why 2-3 deg C is often referred to as a tipping point or threshold for dangerous anthropogenic interference. Warmings much greater, say 5 deg C, would be a calamity of Biblical proportions ... real Wrath of God stuff.
Make no mistake. Estimates of harms and benefits are highly uncertain. However, there is clearly a significant risk of serious net harms over the next century as the climate warms. People arguing that there is no risk of serious harms are either dishonest or disconnected from reality.

* For the record: While most plants do grow better as atmospheric CO2 increases, there's dispute about whether this means that plants will grow better under global warming scenarios. While CO2 is definitely going up, which will help plant productivity, there are other changes that might not benefit plants, like changes in precipitation patterns, soil moisture, migration of invasive species, etc. Overall, it's unclear how much plant productivity will actually increase.

Thursday, October 05, 2006

Answers to a few questions

Although I've answered these in various posts, I think it's useful to repeat this material. Recent commenters continue to bring these questions up.
  1. Is the Earth warming?

  2. Duh. Of course it is. Next question.

  3. Are humans to blame?

  4. I blogged on this point here. The bottom line is that we are virtually 100% certain that humans are contributing to the present warming, and we think it's likely that humans are contributing most of the warming over the last few decades. However, no one credible argues that humans are responsible for ALL of the warming.

  5. Will the effects of climate change be beneficial or disastrous?

  6. Clearly, some people will benefit from warming, while others will suffer. There are a lot of dimensions to this (economic, moral, etc.), but I'll just give the broadest answer. For small warming (e.g., 1 deg C over the next 100 years), current thinking is that harms and benefits are largely comparable, although it is estimated that harms still outweigh the benefits. As the warming increases, the harms get much bigger, and begin dominating over benefits somewhere around 2-3 deg C of warming. That's why 2-3 deg C is often referred to as a tipping point or threshold for dangerous anthropogenic interference. Warmings much greater, say 5 deg C, would be a calamity of Biblical proportions ... real Wrath of God stuff.

  7. Can we do anything about it?

  8. I don't know. I think the problem is largely political, but I'm hopeful that we can get our act together in the next decade to make the technical and societal changes necessary to stabilize atmospheric CO2 around 550 ppmv (double pre-industrial levels). If we fail, then we move on to other options (like geoengineering), but I think we have to at least make a legitimate effort to to reduce emissions.

Alternatives to peer review

For those interested in the process of peer review, take a look at this interesting article.

For those not familiar with the concept of "peer review," here's a short explanation. Scientific journals will not publish a paper until it has been critically scrutinized by other scientists (usually two or three) who are experts on its subject. In this process, called peer review, the reviewers’ job is to look for any errors or weaknesses – in data used, calculations, experimental methods, or interpretation of results – that might cast doubt on the conclusions of the paper. The process is usually anonymous, so reviewers are free to give their honest professional opinion without fear of embarrassment or retribution.

Peer review is one of the cornerstones of modern science. And succeeding at peer review counts for everything in a scientific career. For scientific work to attract attention and respect, it has to be published in peer-reviewed journals. Proposals for research funding must also go through peer review. For scientists to get and keep jobs and achieve all other forms of professional reward and status, they must succeed at getting their work through peer review.

Because of its central place in science, I'm quite skeptical that non-peer-reviewed journals will be successful. It seems like likely that non-peer-reviewed journal publications will simply not count the same as peer-reviewed publications for things that matter, like tenure decisions, and that people will not publish first-rate work there. Rather, it will be second-rate work that has been rejected from peer-reviewed journals that will end up in the non-peer-reviewed literature.

One of the complaints against peer review is that good science is sometimes held up or even rejected by stubborn or biased reviewers, thus hurting both the authors and the scientific community. My experience is that this is rarely a real problem: if your paper gets rejected by one journal, you can always submit it to another. And an author can always request that a particular person (or two) not serve as peer reviewer. If a paper gets rejected by several groups of reviewers picked by several journals, then it probably doesn't deserve to be published anywhere.

In addition, implementing a non-peer-reviewed journal simply trades one problem for another. While legitimate science might sometimes be delayed or rejected by peer review, a lot of really bad science is correctly filtered by peer review. By eliminating peer review, you will unleash all of the bad science on the community. This seems to me to be a bad idea.

In any event, it looks like the experiment is going to be run, so we'll all see how this turns out.

Tuesday, October 03, 2006

Sunday, October 01, 2006

"An Inconvenient Truth" blitzkrieg

I've noticed something interesting going on. SciGuy reports that more than 20 Houston-area churches will show Gore's film on climate change next week. Over on Prometheus, Roger Pielke Jr. blogged that the film will be shown at the University of Colorado, and then there'd be a panel discussion following. I have been invited to attend a screening of the film at SMU, and then be part of a panel discussion there.

It seems obvious that there's a concerted effort to get this movie out there. I'm not sure who's behind it (if any of you know, please let me know), but I think that these showings of the movie and panel discussions will definitely benefit the debate. While I might quibble with a statement here or there in the movie, overall I think the movie is pretty accurate. Much more accurate, in fact, than recent Wall Street Journal editorials on the subject. I think that most people come out of the movie better informed than when they went in.

Climate change and tobacco, part II

A while back, I blogged about the connection between denialists on climate and tobacco. Here is an interesting BBC report on the same subject:
(tip 'o the hat to random variable blog via deltoid)

Friday, September 29, 2006

When the history of climate change is written ...

I'm quite convinced that the citizens of the Earth will at some point band together and attempt to stabilize atmospheric CO2 abundances . If I were a betting man (and I am), I would bet that an international agreement will be reached during he first term of the next U.S. President (2009-2013). Let's hope it's sensible and successful.

When the history of AGW is written, I believe that three occurrences will have been crucial in setting the stage for CO2 emissions reductions:
  • Hurrican Katrina - we can argue about the effect of AGW on hurricanes, but there's no question in my mind that Katrina had an affect on how many view AGW
  • Drowning polar bears - images play a key role in policy debates, and images of so-called charismatic megafauna can quickly become iconic. These images appeal to the obligation many feel for stewardship of the planet.
  • Al Gore - Love him or hate him, his movie has had a huge effect on the debate --- not on the hard-core Gore haters, nor on the AGW believers, but on the undecided middle of the debate. And not necessarily because they went to see his movie, but because his movie has kept AGW in the news and on the public's radar.
Together, these three events have been crucial in generating the growing wave of awareness on the issue. In fact, I think we've recently passed a tipping point, where the question has changed from whether to take action to what form that action will take.

Wednesday, September 27, 2006

Has the climate warmed since 1998?


1998 was a blistering hot year, caused primarily by an enormous El Nino that year. 2005 was hot, too, and while some claim it was hotter than '98, my view is that it was a statistical tie.

Does this mean that global warming stopped in '98? (as argued in places like this) The answer is no. To illustrate, let's consider some synthetic data I made up.

First, let's assume that the human contribution to globally averaged temperatures looks like this:

This is 0.2 deg C per decade, similar to measurements over the past few decades. But as we all know, other things also affect our climate. A particularly good example is El Nino. During an El Nino, the globe warms considerably compared to non-El Nino years. El Nino's occur every few years, so let's assume that El Nino's contribution to global temperature looks like this:

Now let's sum them.

As one can see, the El Nino signal in our little example (and in reality) totally dominates the human-induced signal.

So if one wants to know how much "global warming" has occurred since 1998, one has to subtract out the influence of El Nino. If one does that, then 2005 is much hotter than 1998, and global warming is alive and well.

The important lesson to learn here is one of time scales. Looking at the temperatures from 1998 to 2005 means you have about 8 years of data. This is comparable to the El Nino cycle time. If one looked at much longer times (e.g., a few hundred years), the effect of El Nino would be less important and more obvious. To illustrate that, here's the same two time series extended out 200 years.
As you can see, the upward 0.2 deg per decade signal is quite obvious in this plot.

The same is true if the time series is much shorter than the time scale of the variation. That's why we don't have to worry about ice age/interglacial variations in our analysis of the warming of this century. But by picking a time scale that is comparable, it maximizes the confounding effects on any trend calculation.

People who argue that global warming stopped in 1998 are 1) clever advocates who are willing to mislead to win the argument or 2) don't understand much about the climate system.

Tuesday, September 26, 2006

Good new FAQ on global warming

My colleague Steve Sherwood has a good FAQ on global warming here. It's another resource you can show your Aunt Petunia ... you know, the one that still doesn't believe that atmospheric CO2 is increasing!

Monday, September 25, 2006

Still more Bush on global warming

Following on my series of blogs on Bush, SciGuy had a link to this video. A little comedy to lighten your day!

Sunday, September 24, 2006

Are scientists biased?

One of the parts of the Wegman report that I objected to was his characterization that scientists are biased towards getting results that confirm the underlying paradigm of AGW:
there is a tightly knit group of individuals who passionately believe in their thesis. However, our perception is that this group has a self-reinforcing feedback mechanism and, moreover, the work has been sufficiently politicized that they can hardly reassess their public positions without losing credibility.
What this idea overlooks is that one gets ahead in science not by agreeing with previous work, but by advancing new ideas. The bigger the new idea, and the bigger the old idea that it replaces, the more fame and success accrue to the scientist. Look at famous scientists through history and you won't find a single one that got there by agreeing with the prevailing wisdom.

If you're a member of the so-called "hockey team," you're not going to get much credit or respect from the community if all you do is agree with hockey stick. Rather, an individual scientist will do much, much better if he can show that his competitors' (aka colleagues) work is faulty or biased. And that same individual scientist will do much worse if his or her work is viewed as faulty or biased. This incentive to destroy previous work explains why, in any group of a few scientists, there will be at least two that hate each other.

Scientists are human and all of us have personal biases. But because scientists know that important ideas they advance will be re-tested by other scientists, there is a strong incentive to be careful and conservative in their claims.

People that argue that there's some type of "conspiracy" among climate scientists to increase funding by producing "alarmist" science are either a) a clever advocates trying to obstruct AGW policy by attacking the science or b) someone who doesn't understand science.

Thursday, September 21, 2006

My thoughts on the hockey stick

A few people have asked me what I think about the hockey-stick debate. Here are a few thoughts.

(1) I never say whether the hockey stick is "right" or "wrong". Labels like that are ambiguous and misleading. I actually don't know whether it was wrong or not, but I do know that some of the best research has turned out, in the end, to be wrong; it's value was in pointing the community towards an interesting question.

(2) I adopt the NRC's party line that we simply cannot say whether the MWP was warmer or not than the present. I've seen a lot of people misinterpret this to mean that we can now say that the MWP was warmer than present. That's incorrect --- the uncertainty cuts both ways. We cannot say today is warmer than the MWP or that the MWP is warmer than today. We just do not know.

(3) The hockey stick plays little or no role in attribution of the recent rise in temperatures to human activities. For example, see this blog entry where I talk about why we think much of today's warming is caused by man. Note the absence of any reference to the hockey stick. Thus, the statement that humans are contributing to the present day warming remains unscathed.

(4) The scientific community should provide code and data to any interested party. Not being forthcoming with these things seems to me to violate the ethos of science, well summed up by the AGU's motto: "unselfish cooperation in research." And it makes us look bad.

Wednesday, September 20, 2006

Speech by Boehlert

(thanks to a tip from a reader)

I'm really going to miss Sherwood Boehlert, who's retiring at the end of the term. Here's why:

September 20, 2006
Science Committee Press Office: 202-225-4275
Joe Pouliot,
Zachary Kurz,


WASHINGTON - House Science Committee Chairman Sherwood Boehlert (R-NY) today delivered the following speech at the Climate Institute's Washington Summit on Climate Stabilization:

I know that yesterday you heard from some of the world's leading scientists about the frightening possibility that the earth's climate may change more quickly and abruptly than expected, and whether there's anything that can be done to avoid that.

Well, this morning's session should offer a break from all of that. Instead, I'm going to talk about the frightening possibility that Washington's political climate may not change more quickly and abruptly than expected, and whether there's anything that can be done to avoid that.

Certainly, without abrupt political climate change, it's going to be next to impossible to do anything about global climate change.

Let me hasten to add that by calling for "political climate change," I'm not covertly advocating a change in political party control. There are segments of both parties that support action to address climate change, and segments in both parties that don't.

But right now, those of us who seek action are confronted by ideology, by fear, by a reluctance to lead, by apathy, by comfort with the status quo. All of that has to change, and I think it is beginning to change.

But before I get to some of the better news, let me give you one illustration of how hard it is to make progress right now. One of the simplest steps we could take to reduce greenhouse gas emissions would be to increase the mileage of our auto and light truck fleet.

It just so happens that increasing mileage would also enhance our national security, bolster our economy, and save consumers money.

And, according to the National Academy of Sciences, we could increase mileage substantially, using technology that already exists, without any reduction in safety. So to exaggerate only a little, this should be a no-brainer - even without taking climate into account, but especially when climate concerns are added to the mix.
So has Congress voted to increase mileage requirements, known as Corporate Average Fuel Economy, or CAFE standards? No.

The proposal has been defeated repeatedly in both the House and the Senate by a mixture of conservative ideologues, and Republicans and Democrats who are lobbied by automakers and/or the United Auto Workers. And I should know because I'm the guy who offers the amendment in the House each time.

Now in the House at least, we do a little better each time. We got 160 votes in favor in 2001, 162 in 2003, and 177 in 2005, and we know we would do better still this year because Members have declared publicly that they've changed their position.

Unfortunately, we can't seem to get a vote scheduled this year, despite high gasoline prices, perhaps because we're on the cusp of victory, at least in the House.
But my point is a more sober one: if we can't make a relatively simple change in mileage regulations - a change to an existing regulation that doesn't even require new technology and that would have numerous benefits aside from the climate implications, then what does that say about our ability to reduce greenhouse gas emissions? It certainly doesn't say anything good.

So all of us who want to see some action on climate change have our work cut out for us.

In the House, many, perhaps even most Members, still question whether climate change is a genuine phenomenon. The scientific consensus has simply not pierced through the ideological barriers. And there are briefings almost weekly sponsored by groups that argue that climate change science is some kind of environmental conspiracy, and they bring seemingly credentialed people forward to make their claims.

We've even had to confront the situation where Members of Congress have tried to investigate scientists whose views made them uncomfortable.

In July 2005, the Energy and Commerce Committee initiated an investigation of Michael Mann and his colleagues who wrote the so-called "hockey stick" article. I took that Committee to task, arguing that raising questions about scientific methods and conclusions was fine, but intimidating scientists was not.

As I wrote to that Committee, "The only conceivable explanation for the investigation is to attempt to intimidate a prominent scientist and to have Congress put its thumbs on the scales of a scientific debate. This is at best foolhardy; when it comes to scientific debates, Congress is 'all thumbs.'"

Eventually, I asked the National Academy of Sciences to convene a panel to look at the historic temperature record. That panel came up with what I think just about everyone views as a balanced and thoughtful report.

It took issue with some of Dr. Mann's initial methods and specific conclusions, but it confirmed that the past few decades have been hotter than any time in at least the last 400 years and probably longer.

This July, the Energy and Commerce Committee had a hearing on that report, which was a legitimate Congressional step to take.

We'll have to wait and see how the testimony at that hearing will influence the future thinking of the Members of that Committee.

I should say that the White House position has been far more nuanced than that of most House Members. The President has stayed within the bounds laid out in the 2001 National Academy of Sciences report on climate change that he requested.

The emphasis of the White House view changes a little depending on who is speaking, but the White House has not been in the camp of those who deny climate change, although it has shied away from mandatory action to combat climate change - unfortunately, in my view.

Now, we're seeing rumors in the media that the White House may be planning a major climate announcement in the next few weeks. I have no idea if that is true.
I'm more concerned about how the Administration is implementing its existing climate plans and programs. Our Science Committee's Energy Subcommittee has a hearing later today, for example, on the Administration's strategic plan for the Climate Change Technology Program, or CCTP.

I have the highest regard for Energy Secretary Bodman, an alumnus of Cornell and MIT, who is a true advocate for science and a candid and creative thinker. But I am not a big fan of the strategic plan, which is more of an inventory of existing programs and a wish list of possible future ones, than a planning document with clear priorities.
Moreover, as is often the case with this Administration, the plan is silent on what policies might be necessary to actually get new or improved technologies into the marketplace.

"If someone builds it, they will come" is not much of a technology deployment strategy, especially when the immediate and significant benefits of new technologies may accrue more to the public as a whole than to the individual consumer.

The example of hydrogen illustrates my point. Hydrogen has a long, long way to go to be a useful energy source, but its potential is enormous and worth pursuing. But we're not going to be driven to a hydrogen economy simply through market forces.
Every transportation revolution in American history - canals, railroads, turnpikes, air travel, interstate highways - has been underwritten by the government.

It's folly to think that that wouldn't be true of a hydrogen revolution, especially since a hydrogen "revolution" would require displacing our current infrastructure, an infrastructure that works just fine from an individual perspective.

But the good news is that the Administration understands that we need new technologies to address climate change, and that the government has a role in developing them.

The third federal player is the Senate, and Senator Bingaman can focus on them. But the Senate, thought it pains me to say it, has been the leader on climate change policy, albeit with minimal results.

Legislation that is explicitly designed to address climate change has at least come up for a vote in the Senate - something that is almost inconceivable in the House. And bills like the McCain-Lieberman cap-and-trade proposal have done respectably, although they have not been passed.

One of the most hopeful events in Washington related to climate change all year was the all-day session that Senator Domenici and Senator Bingaman held back in April to have serious discussions about how greenhouse gas emissions might be regulated.
At that session, not only the senators, but also key business leaders, expressed openness to finding ways to control emissions.

And an even more hopeful sign is what's been happening in the states. California and the northeastern states are trying to take concrete action to reduce greenhouse gas emissions. And many other states and localities have expressed interest in reducing their emissions.

Given the way states compete for jobs and the fact that the impacts of greenhouse gases are felt internationally, not locally, this state interest is not what one would expect. But it's a sign that the public is beginning to sense that this is a problem that must be addressed.

And, of course, the key to creating abrupt political change will be to further engage, educate and inspire the public. Politicians are responsive to public opinion, even in this day and age of political manipulation and multinational corporations.

In fact, in this era of the Internet and constant polling, politicians may be, if anything, too responsive to momentary shifts in public opinion.

So what's needed is for scientists and politicians and concerned business leaders to redouble our efforts to reach out to the public through as many different forums as possible. Complacent satisfaction with our own right beliefs won't carry the day.

The abolitionist Wendell Phillips famously said, "One man on the side of God is a majority." But while that no doubt got Phillips through some lonely times, the anti-slavery advocates didn't gain political influence until they won more converts.

So scientists have to engage. And what scientists say needs to be clear and accurate and modulated and persuasive. Hyperbolic claims will only diminish scientific credibility over time.

Scientists have to be clear about what we know, and about what we don't. They need to be "up front" about uncertainties - and about the potential costs of waiting until all uncertainties are resolved.

(I always quote former Governor Tom Kean's line about acid rain. He said that if all we do is continue to study acid rain, "we'll have the best documented environmental disaster in history.")

We need to lay out an argument for action, but we won't win by mimicking the opposition's tendencies toward rhetorical excess.

And we need to keep in mind that if we win - if the political environment changes so that a desire for action takes root - then our hardest tasks will be ahead of us.

We may end up longing for the days of debate over whether climate change is real - because the intellectual and political decisions we will have to make to confront climate change - whether through mitigation or adaptation or, more likely, both - are going to make today's debates seem like child's play.

I don't think there's anything about the European experience post-Kyoto, for example, that should make us think that this is going to be easy.

So, like abrupt climate change, abrupt political change will present us with a different and problematic world with new and uncomfortable choices. But unlike abrupt climate change, a changed Washington should give us reason for hope, despite all its attendant difficulties.

Climate change discussions can be consumed by gloom. They can remind me of the opening of Woody Allen's classic essay, "My Address to the Graduates." It starts: "Today, we are at a crossroad. One road leads to hopelessness and despair; the other to total extinction. Let us pray we choose wisely."

I think our choices are a little better than that, and if they're not, we'll never win over the wider public.

We have had successes in the recent past in winning over skeptics and taking action. We have controlled the CFCs that created the ozone hole. The Bush Administration has imposed strict new regulations to control fine particles - the health effects of which were still the subject of angry debate not so long ago.

These problems were easier to tackle than climate change, but they didn't seem very easy at the time. The public and policy makers had to be convinced of the science so that difficult concrete steps could be taken.

So I look forward to working with all of you, to continuing to learn with all of you, so that we can create a political climate in which action is possible on climate change.

That's going to take a lot of tough and honest discussion. But it can be done. If we break through the current apathy and cynicism, we can revive American politics, and our environment will be the beneficiary.

Thank you.

What is the Earth's ideal climate?

In another thread, a commenter asked an interesting question: what is the Earth's ideal temperature? This question is often used as a version of the "AGW might be good argument": the point was that perhaps the ideal temperature was warmer than today's, so climate change might actually be beneficial.

Given everything else equal, one might be able to make an argument that a warmer world might be better. However, everything else is NOT equal. Rather, we have adapted to our present climate and made significant investments in these adaptations. We build cities in places where it makes sense to put them (with the notable exception of New Orleans), we build infrastructure where it makes sense to put infrastructure, we perform economic activity where such activity makes sense. If the climate changes significantly, it might take enormous investments to adapt to our new climate. Our previous investments in infrastructure might become worthless.

Consider this example. You build a sawmill next to a roaring river, using the river as a power source for the mill. Now AGW causes the precipitation pattern to change and the river moves miles away. In this new world, the river might have higher flow rates, which would provide MORE energy to the mill, which would be a good thing --- if the mill were still on the river. But the mill is no longer anywhere near the river. So you have to build a new mill on the banks of the new river. This investment in new infrastructure is potentially expensive, and some countries will not be able to afford it.

My point here is that any question about suitability of future climates has to take into account our investment and adaptation to our present climate.

Monday, September 18, 2006

More on Bush climate u-turn

I received an e-mail from a distinguished scientist (member of the Academy) saying:
A few months ago I heard from a friend that Karl Rove had met privately with a small group of global warming luminaries that included Bob Corell, and that Rove was listening intently and sympathetically to what they were saying. The article at this link predicts that something big is about to happen, perhaps at Rove's direction. Bizarre as it sounds, I'm inclined to believe it.
I blogged on this recently here. I don't normally put too much faith in hearsay, but I also believe there's a grain of truth here. My current theory is that this is a "trial balloon" put out by the administration to see how much screaming and howling there is.

Overall, however, this is not necessarily inconsistent with an evolution in Bush's rhetoric over the past few years. In 2001, he emphasized the uncertainties in our science. As that position moved from shaky to downright untenable, however, his rhetoric shifted to fairness (China hasn't signed on, etc.) and economic (we'll put people out of work). He really doesn't argue the science anymore.

Stay tuned for more!

Thursday, September 14, 2006

Important news

An interesting news report is circulating around the blogosphere today. Allegedly, the Bush administration is going to propose we limit CO2 to 450 ppmv by the year 2106.

If true, this as an incredibly important event --- it will move the debate from "should we take action?" to "what action should we take?" In other words, the debate will evolve into a discussion of what the target should be --- and this is (in my opinion) exactly what we should be talking about.

The long lifetime of CO2 in the atmosphere means that we cannot wait for 50 years to start reducing emissions if we want to hit 450 ppmv. In fact, we need to start deviating from our baseline in the next 10 years or so in order to avoid having to make large and disruptive cuts later. And the near-term actions required are pretty much the same for a wide range CO2 targets and timelines. Thus, while some will critize the target date of 2106, it will be one or several decades before actions in pursuit of this target preclude more ambitious targets.

ps: I've turned on "comment moderation" on the blog as a test, so your comments might take a few hours to appear. Your patience is appreciated.

[Note added later: The more I think of this alleged proposal, the more puzzled I am about it. The target (450 ppmv) and the time period (2106) are not really consistent. It is almost certainly the case that in order to stabilize CO2 at 450 ppmv at the beginning of the 22nd century, one has to be close to or at that target in the middle of the 21st century. So why put the target date 50 years later? Perhaps this is a cynical election year ploy, as suggested by several commenters. Or maybe there's something I'm not considering. Any thoughts on this are welcome.]

Wednesday, September 13, 2006

Tuesday, September 12, 2006

How do you define success?

Some people define it in terms of Nobel Prizes or election to the National Academy. But I define success as being interviewed by The Houston Chronicle's SciGuy, Eric Berger.

At any rate, I've made it!!! You can check out the interview here and listen to a recording of the entire interview here.

Sunday, September 10, 2006

Editorial in the Economist

Check out this excellent editorial in the Economist. I have a few nits here and there with it, but overall it is what I would have written if I were a much better writer. I think it makes the essential points with great precision.

Friday, September 08, 2006

Three caveats

Not everyone appreciates the carefully caveated statement in the IPCC's TAR about the attribution to humans of the current warming. Let's take a closer look at the exact statement:
In the light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations.
There are three important caveats in this statement, which are often ignored by strawman-toting advocates.
  1. "most of the observed warming": this says that humans contributed > 50% of the warming, but it leaves the door open for a significant amount to be due to non-human influences.
  2. "last 50 years": this says that we can identify the hand of humans in only the recent warming; before that, the data are too poor to unambiguously assign the cause of the warming.
  3. "likely": in the carefully nuanced language of the IPCC, "likely" denotes a confidence of about 75%. Thus, there is a possibility that this statement is wrong. This reflects the fact that our knowledge of the climate is imperfect, and it is possible though unlikely that new research could significantly revise our understanding of the climate system.
The main problem is that when advocates use the IPCC in their policy arguments, the carefully crafted language is abandoned for much stronger statements that support the advocates position. When these positions turn out to be false, the blame falls (unfairly) on the IPCC. Clearly, I think we all need to read the IPCC with the scientific precision with which it was written.

Thursday, September 07, 2006

Recovery from the little ice age?

One argument often heard in the AGW debate goes something like this:
The Earth may be warming, but human activities are not responsible: Even if the Earth is warming, it is obviously part of the continuing recovery from the “little ice age,” the cool period from the fifteenth to eighteenth centuries.
This argument tacitly assumes that the Earth’s climate system has a “normal” state that it pushes back to after unusually warm or cold periods, like a stretched spring returning to its normal length. While this might appear commonsensical, it has no foundation in either the record of how climate has varied or the fundamental physics of the atmosphere. The Earth’s climate has no “normal” state to which the climate seeks to return, so there is no reason to expect that an unusually cool period will be followed naturally by a return to warmer conditions.

Rather, when interpreting cause-and-effect in the temperature record, one has to consider the forcings. One can make a strong argument based on solar proxies (like sunspots) that the increasing temperature between the 17th century to about the middle of the 20th century was due to increasing solar forcing.

However, for the particularly rapid warming of the late 20th century, we have a good knowledge of the forcings of the climate. As I described here, we can eliminate solar variability as a primary driver. In fact, the only forcing that explains the warming is the increase in greenhouse gases.

In summary, there is no evidence that today’s particularly rapid warming is caused by the same thing as caused most of the warming over the last few centuries. By considering the forcings, we can conclude that most of the recent warming can be attrbituted to human activities. Thus, the argument that today's warming is simply a continuation of some natural trend is unsupported by any science.

Monday, September 04, 2006

A sensible position

Can be found here. I might have re-written the title, if I were the editor, but I generally agree with the sentiment expressed that both adaptation and mitigation will be necessary to deal with the climate change problem.

North on the hockey stick

My colleague Jerry North was the chair of the National Academy panel that investigated the hockey stick. Last week he gave an interesting seminar to our department about the experience. You can view the seminar here.

[Techincal details: it's a 40 MB file, so it'll take some bandwidth. It's in mp4 format --- if you have a recent version of quicktime on your computer, you should be able to view this. It runs just over an hour, so grab some popcorn and enjoy!]

Saturday, September 02, 2006

Fill in the blanks

Consider the following diatribe against the system that I found on the web:
If a contest were held to award the most scientifically baseless, politically oppressive, morally bankrupt, economically destructive environmental farce, the hands-down winner would be the theory of global warming.

Whenever a major action is being dictated, especially at the national level, you should ask yourself, "Who benefits?" If your answer includes arrogant "scientists," trendy politicians & faceless corporate bureaucrats, you can safely assume that scandal is not far behind. Obviously these do-gooders will proclaim that you are going to benefit because they are doing you a big favor; one you don't remember requesting. If you're starting to feel queasy, good.

When I began studying the theory that greenhouse gases were affecting the climate, I found less & less, not more, credibility. What I did find however is that people who will make money on this scandal support it, & choose to deny or ignore the facts. This trend continues at an accelerating pace.
This sounds like pretty routine stuff, right? Actually, I've edited a few words: the bold words have been replaced as follows:
  • "theory of global warming" was really "the banning of CFCs."
  • "greenhouse gases" was really "CFCs"
  • "climate" was "ozone layer"
The point here is that the arguments you hear about climate change are just a re-run of the arguments over ozone depletion. And when the next environmental issues comes up, just replace the bold words with whatever is necessary to attack the science of that issue. You see ... it's easy to be a "skeptic"!

Thursday, August 31, 2006

Whose opinion counts for the "consensus"?

I thought I would answer a question that several people have posed to me recently. When determining whether a scientific consensus exists, whose opinion counts? My answer is: look for consensus in the peer-reviewed literature.

As I discussed in a recent post, the scientific enterprise determines whether to accept or reject a claim by repeatedly testing it, and publishing the results of those tests in the relevant journals. Claims that have been repeatedly tested are accepted, with the confidence given that claim proportional to how numerous and rigorous the tests have been. One can determine which claims have been repeatedly tested in the "crucible of science" and therefore accepted, as well as how confident we are in our acceptance of that claim by reading the peer-reviewed literature.

Viewed through my definition, there is clearly a strong consensus that 1) the Earth is warming and 2) that humans are likely to be the dominant cause of the recent warming.

Might a "consensus" position be wrong? Of course. All knowledge is provisional and subject to future revision as new data comes in. However, as policymakers, the scientific consensus is the position most likely to be correct. In particular, strongly held consensus positions (e.g., smoking causes cancer, the Earth is warming) are verly unlikely to turn out to be wrong. Policymakers can do no better than to follow the scientific consensus in formulating their policy.

Wednesday, August 30, 2006

Interesting development in CA

AP reports an important development in the policy battle of regulating greenhouse gases:
California would become the first state to impose a limit on all greenhouse gas emissions, including those from industrial plants, under a landmark deal reached Wednesday by Gov. Arnold Schwarzenegger and legislative Democrats.

The agreement marks a clear break with the Bush administration and puts California on a path to reducing its emissions of carbon dioxide and other greenhouse gases by an estimated 25 percent by 2020.
Given the success of California at independently regulating pollution from automobiles and driving technological advances that have improved emission performance worldwide, it seems possible that this might be the move that forces everyone else on the GHG-regulation bandwagon. It will be interesting to see how this plays out.

Tuesday, August 29, 2006

The role of consensus in science

In the policy debate over global warming, anti-AGW advocates often disparage "consensus" as a refuge for scoundrels and bad science. However, my experience is that consensus is in reality the cornerstone of science.

Science is a multi-layered, collective, and impersonal process consisting of three parts. First is the individual scientist testing hypotheses according to the norms of his or her field. Second, the results of the individual scientist undergo peer-review and are published for the community to evaluate. At this point a result may be considered preliminary, but not proven. Third, important claims are then re-tested in the "crucible of science" -- they are either reproduced by independent scientific groups or they have their implications tested to insure consistency with the existing body of scientific knowledge. After enough tests/reproductions, a CONSENUS emerges that the idea is correct.

In the end, claims that are repeatedly verified by the scientific community (e.g., the Earth is warming, DNA is a double-helix, CFCs destroy ozone) eventually come to be accepted as true.

A good example is Einstein and his theory of general relativity. When he published his theory, it was not immediately accepted. However, it was rigorously tested by other scientists, most famously by Eddington's observations of star positions during eclipses, and eventually it was accepted as being "true" by the community. In other words, a consensus emerged that it was correct. At that point, people moved on to the next question, using Einstein's theory as a building block to the next interesting scientific question.

The key point here is the importance of consensus. After an idea is sufficiently well tested, everyone simply accepts the idea and people move on. While a scientific consensus might turn out to be wrong, for important and well-tested ideas (e.g., smoking causes cancer, the Earth is warming), it's exceedingly unlikely.

Sunday, August 27, 2006

Is this consistent?

You often hear the following arguments made in the AGW debate:
  1. "There is no consensus in the scientific community about AGW"

    An example can be found here in a discussion of the Oreskes Science editorial:
    "Whatever happened to the countless research papers published in the last ten years in peer-reviewed journals that show that temperatures were generally higher during the Medieval Warm Period than today, that solar variability is most likely to be the key driver of any significant climate change and that the methods used in climate modeling are highly questionable?" Peiser asked.

    "Given the countless papers published in the peer-reviewed literature over the last ten years that implicitly or explicitly disagree with the hypothesis of anthropogenic global warming, one can only conclude that all of these were simply excluded from the [Science Magazine] review. That's how it arrived at a 100 percent consensus!" he added.
  2. "Scientists are afraid to disagree with the apparent AGW consensus"

    This argument can be found in this recent WSJ oped by Dick Lindzen:
    So how is it that we don't have more scientists speaking up about this junk science? It's my belief that many scientists have been cowed not merely by money but by fear.
So which is it? Is there a vigorous debate in the scientific community about AGW, as Peiser suggests? Or is there no debate because skeptical scientists are "cowed", as Lindzen suggests? These arguments can't both be right.

Of course, perhaps they're both wrong. Maybe there's no debate because the science solidly supports the conclusion that humans are the primary driver of today's warming ... of course Peiser and Lindzen don't mention that possibility. Draw your own conclusions.

Friday, August 25, 2006

Thursday, August 24, 2006

"Climate changes naturally"

One of the most irritating red herrings in the climate debate is the following argument:
The climate has warmed and cooled naturally over its entire history, so 1) the present-day warming must therefore be natural, and 2) we shouldn't worry about it.
Point 1 I debunked here. The science strongly supports the conclusion that humans are contributing significantly to today's warming. To understand why I object to point 2, let's consider the following image:

Following point 2 above, we should tell the pilot of that plane not to worry ... after all, the plane is in a descent, but this plane has descended lots of times before. Why should this descent cause any concern???

The answer should be obvious. This descent is quite different from previous descents, and one that the pilot will not survive. Similarly, the evidence we have is that the present-day warming is far more rapid than most past climate variations. Before people jump on me, I know there is some evidence that some past changes have been rapid (e.g., the cooling during the Younger Dryas), but these were all associated with reorganizations of the circulation of the atmosphere-ocean system that are not now occurring. Thus, it might be that today's warming has no precedent in the entire history of the Earth. Because of the quality and sparseness of data, there is significant uncertainty in this conclusion, but speaking as a citizen, just the possibility that this is true causes me grave concern about the state of the climate system.

Tuesday, August 22, 2006

Being a skeptic: a lifetime commitment

For those with an interest in climate change "skepticism" (as practiced by Fred Singer et al.), you might be interested to know that the same people that argue that the science of climate change is flawed also argued that the science of ozone depletion was flawed.

From :
You see, Sallie Baliunas is Staff Astrophysicist at the Harvard-Smithsonian Center for Astrophysics and Deputy Director of the Mount Wilson Institute.

Is Dr. Baliunas a lone ‘contrarian’?

Hardly. Any list of ozone depletion theory ‘contrarians’ is today likely to number hundreds of scientists world-wide with substantial credentials and credibility.

Among them find: Dr. S. Fred Singer, Senior Fellow with the Alexis de Tocqueville Institution, Dr. Hugh Ellsaesser of the Lawrence Livermore Laboratory, Dr. Thomas Gold of Cornell University, Dr. Patrick Michaels of the University of Virginia, Dr. Marcel Nicolet, world famous atmospheric scientist, Dr. Haroun Tazieff, whose Tazieff Resolution calls for a retraction of the Montreal Protocol, Dr. William Happer of Princeton, and Dr. Frederick Seitz, past head of the National Academy of Science.
Do those names look familiar? I believe that skepticism in the face of advocacy is a virtue, but this group gives skepticism a bad name. And I'm sure that when the next environmental issue arises, we can all guess who'll be "skeptically" investigating the science.

Monday, August 21, 2006

Tobacco industry racketeering case: Interesting reading

The decision in the Justice Department's tobacco industry racketeering case can be downloaded here. Starting on page 219, the report discusses how tobacco companies engaged in systematic distortion of the science to continue selling cigarettes. Here are a few headings from the table of contents:


A. Defendants Have Falsely Denied, Distorted and Minimized the
Significant Adverse Health Consequences of Smoking for Decades


b. By 1953, Defendants Recognized the Need for
Concerted Action to Confront Accumulating
Evidence of the Serious Consequences of Smoking

3. Developments Between 1953 and 1964
a. Between 1953 and 1964, the Evidence Demonstrating
that Smoking Causes Significant Adverse Health
Effects Grew Although No Consensus Had Yet
Been Reached

b. Before 1964, Defendants Internally Recognized
the Growing Evidence Demonstrating that Smoking
Causes Significant Adverse Health Effects

c. In the 1950s, Defendants Began Their Joint
Campaign to Falsely Deny and Distort the
Existence of a Link Between Cigarette Smoking and
Disease, Even Though Their Internal Documents
Recognized Its Existence

As I read this, I cannot help but get the feeling that this tried-and-true strategy is presently being applied to the global warming debate.

[sorry for the crappy formatting]

Saturday, August 19, 2006

More on the water vapor feedback

The water vapor feedback is one of the most important processes in our climate. In fact, the feedback is responsible for a significant part of the warming predicted to occur over the next century.

A reader asked an interesting question in response to a recent post on the water vapor feedback: What peer-reviewed evidence exists for a positive water vapor feedback? What about a negative water vapor feedback?

Let's take the negative feedback first. I did a quick search on the Web of Science and found out these statistics:
70 papers contained the phrase “water vapor feedback”
18 of them contained “negative” and “water vapor feedback”

If you go through the abstracts, you find that only four articles talk about a negative water vapor feedback (in other abstracts, the word “negative” was modifying another phrase). I’m adding a fifth paper that was not flagged in my search because it was published in 1990, before the WOS included abstracts. Also, I’m dropping one paper for reasons I won’t go into here.

Here is the resulting list of peer-reviewed literature on the negative water vapor feedback:
1. Lindzen, R. S. (1990), Some coolness concerning global warming, Bull. Amer. Meteor. Soc., 71, 288-299.

2. Sun, D.-Z., and R. S. Lindzen (1993), Distribution of tropical tropospheric water vapor, Journal of Atmospheric Sciences, 50, 1643-1660.

3. Sun, D. Z., and R. S. Lindzen (1993), Water-vapor feedback and the ice-age snowline record, Annales Geophysicae, 11, 204-215.

4. Lindzen, R. S., M.-D. Chou, and A. Y. Hou (2001), Does the Earth have an adaptive iris?, Bull. Am. Met. Soc., 82, 417-432.

Hmmm. There’s a pattern here that I just can’t quite figure out. Just joking. The pattern, of course, is that only Dick Lindzen has been able to publish a paper arguing for a negative water vapor feedback. But if you look carefully at the papers, they make a much weaker argument than you might expect.

Paper 1 is considered wrong by everyone, including Lindzen. In fact, paper 2 was written to correct the defect in paper 1. Paper 2 mainly discusses how tropospheric water vapor is regulated. Its discussion of the water vapor feedback is limited to a short discussion of how a negative water vapor feedback might plausibly arise, but no evidence of such a feedback is given. I cannot remember what’s in paper 3, and I can’t find a copy. However, based on the date and author list, it’s likely that it contains much of the same as in the other 1993 Sun and Lindzen paper.

In paper 4, Lindzen resurrects his idea from paper 2, and provides some data to argue that indeed a negative water vapor feedback does exist. Unfortunately (for him), subsequent tests of other scientists failed to verify this idea. At the present time, there is virtually no support in the community for it. Lindzen still gives talks on this and claims that the iris hypothesis is still viable. However, as far as I can tell, no one, including Lindzen, is working on it, so that indicates exactly how vibrant the idea is.

So let’s summarize. There have been a very small number of articles written that argue for a negative water vapor feedback. Virtually all have been written by Dick Lindzen. None have stood the test of time.

Now let’s turn to the other side. What evidence is there for a positive water vapor feedback. First, there are 25 papers that contain “positive” and “water vapor feedback”. Many of these papers are recent (written in the last 2-3 years). Going through the abstracts reveals that most of these papers argue in favor of a water vapor feedback. Many conclude this directly from data, not from any type of GCM analysis. In addition, the papers were written by a large number of different scientists.

Here are a few positive-feedback papers that you might want to take a look at (just a small subset of the literature):
1. Minschwaner, K., and A. E. Dessler (2004), Water vapor feedback in the tropical upper troposphere: Model results and observations, J. Climate, 17, 1272-1282.

2. Minschwaner, K., A. E. Dessler, and P. Sawaengphokhai (2006), Multi-model analysis of the water vapor feedback in the tropical upper troposphere, J. Climate, accepted.

3. Soden, B. J., et al. (2005), The radiative signature of upper tropospheric moistening, Science, 310, 841-844.

4. Sherwood, S. C., and C. L. Meyer (2006), The general circulation and robust relative humidity, J. Climate, in press.

5. Dessler, A.E., and K. Minschwaner, An analysis of the regulation of tropical tropospheric water vapor, J. Geophys. Res., submitted.

[pre-prints of the Sherwood paper can be found on his web page; if you want a pre-print of paper 2 or 5, let me know].

These are just a few of the more recent papers. A bunch more exist, written by different scientists using different data.

Thus, the evidence in favor of a positive water vapor feedback is strong, with multiple peer-reviewed analyses reaching this conclusion. The evidence that the feedback is negative is weak: only Dick Lindzen argues it, and his arguments have been roundly rejected by the scientific community.

Also note that Bill Gray hasn’t published anything on this topic. That’s because he does not have a testable hypothesis nor any data, both of which would be required. Nor can he criticize the published literature on this subject because he has not read these papers.

The upshot: we can conclude that the scientific community agrees that the water vapor feedback is positive. Arguments to the contrary are distortions of the science.

[Note: I recognize that these WOS-type analyses have their pitfalls. But as a scientist who publishes in this area and who has read (I think) all of the relevant literature, I can attest to the fact that this WOS analysis has got it right: there is just about zero evidence to support a negative water vapor feedback.]

Friday, August 18, 2006

The impending disappearance of Pluto

A committee of the International Astronomical Union has proposed a new definition of "planet" which will be voted on next week in Prague. A planet would be defined as a body in orbit around a star and big enough for gravity to make it round.

This reminded me of something my father wrote in 1980 (click to see a larger version):

Interesting editorial in today's Washington Post


Thursday, August 17, 2006


In a recent article that's getting lots of play in the blogosphere, John Fleck wrote:
So how should the public and policymakers, whipsawed by debate, sort out the competing claims? "That's easy," said Dessler, co-author of Cambridge University Press's "The Science and Politics of Global Climate Change." Dessler calls for the use of "expert assessments"- panels of specialists brought together to sort out and summarize scientific information for politicians, policymakers and the public. It's a common technique on all sorts of science-policy questions.

On climate change, a number of such reviews have been done, including work by the Intergovernmental Panel on Climate Change and the National Academy of Sciences. The panels' findings have been consistent and are reflected in the key finding in the IPCC's 2001 "Climate Change: The Science": Greenhouse gas emissions are altering Earth's climate.

Pielke Sr. has a different answer- listen to more diverse scientific voices. He thinks expert panels like the IPCC are inbred, representing a narrow focus on greenhouse gases. "The public is getting a very narrow view of the breadth of issues in climate science," he said.
There's a really interesting point here. I agree with Pielke Sr. that assessments have to include the range of opinions held by the majority of the scientific community. If half of the community says one thing and the other half says something else, then a good assessment will include both views. My sense is that the recent AGU assessment on hurricanes failed in this regard (see also this Prometheus post).

However, we have to be careful about including views that are "too diverse." The goal of a scientific assessment is to let policymakers know what the scientific community thinks on an issue. If 99.9% of the scientists think one thing (e.g., the Earth is warming), then should the assessment include a dissenting view held by 0.1% of the community? I would argue not. Policymakers are often unable to discern a 99.9% position from a 0.1% position, and they look to expert assessments to do just that. If they don't, then the assessment has essentially abdicated its responsibility to clarify the science for the policymakers.

Obviously, this is one of the hard choices that the authors of assessments have. They have to use their judgment about what positions are credible within the majority community and what positions are simply outliers. Writing assessments is a tricky business, but they play such a crucial role that scientific community has to continue to work hard to make them the best possible source of information for policymakers.

Tuesday, August 15, 2006

Pat Robertson on global warming

There's been some interesting discussion on this blog about Pat Robertson's sudden and unexpected conversion to AGW believer.

I wrote that from a policy standpoint, Pat Robertson's conversion is huge. Policies that garner broad support have the best chance of getting adopted, and Pat Roberston brings real diversity into the AGW tent that wasn't there before. In particular, he brings a strong conservative presence that has been missing from the pro-action constituency for at least a decade.

A reader responded:
I don't disagree ... about Pat bringing along a political clout, but really, would you or your distinguished scientists like to stand on the same podium and shake hands or be involved with someone that ridiculous and obviously unhinged? If you welcome him you endorse him, and that is not something a real scientist would do, only a political one.
I reject this argument. While I am gratified that Pat R. acknowledges the strong scientific, economic, and moral case that exists for action on AGW, which I have been arguing for a few years, his endorsement of my position does not mean that I endorse anything else he says. [Ronald Reagan made basically this exact argument when someone odious endorsed him for President --- if anyone has the exact quote, please put it in the comments section.]

Sunday, August 13, 2006

Found in my in-box

A faithful reader of the 'blog has forwarded me this e-mail:

Dear Dr. NameWithheldByRequest,

Fred Singer suggested that I send you the attached documents for your interest. If you would like to join Fred and many others in endorsing "A Call to Truth, Prudence, and Protection of the Poor: An Evangelical Response to Global Warming," we would be honored. You can do that simply by reply e-mail listing your name, title, and (for identification only) institutional affiliation, plus snail-mail address, phone number (for verification only), and a list of your degrees (subject, level, and granting institution). You will note that the "Open Letter" and "Call to Truth" are primarily from evangelicals and to evangelicals but that we have included endorsements by non-evangelicals with special relevant expertise. If you do endorse, please inform me whether I should list you among evangelicals or non-evangelicals. Thank you for your consideration.

In Christ,

E. Calvin Beisner, Ph.D.
Associate Professor of Historical Theology and Social Ethics
Knox Theological Seminary, 5554 N. Federal Hwy., Ft. Lauderdale, FL 33308
Here are copies of the "Open letter," the ironically named "Call to truth," and the press release.

I've read these documents and they're full of the usual crap that gets rolled out for these: Humans are not causing warming; if they are, the warming will be small; and in any event, we can't do anything about this. Their arguments are, by and large, either normative value judgments, or are misleading or downright wrong scientific statements. [Note added in proof: also see the discussion here.]

From a strategic view, however, this type of campaign makes perfect sense. First, the recent emergence of an evangelical coalition in favor of action on climate change was one of the most significant events of the recent past. This represented a titanic shift in the political fault lines of this policy debate. Those opposed to action on climate change had to be terrified that they were on the brink of losing the entire policy debate. So this response makes perfect sense. Second, by arguing about science, they can drag the debate into a complete gridlock, as argued by Jon Miller. The report, with it's appearance of credibility and objectivity, leads the other side (those in favor of action) to leap to an enthusiastic defense of the reality of climate change - and the trap is sprung: the public tunes out (too boring), the media downgrade the story (too complex) and the politicians have the greatest excuse for doing nothing (let's wait until the science is clear).

Wednesday, August 09, 2006

Regional predictions

Take a look at this interesting editorial in the Rocky Mountain News. In it, they talk about whether regional forecasts of climate change are accurate or not:
The majority of scientists working with the United Nations' Intergovernmental Panel on Climate Change think not. The San Francisco Chronicle reported last month that most of them find local climate projections unreliable.
I agree with much of what's in the article, but one thing I disagree with is:
Pielke dismissed the paper on his Climate Science blog (, stating that Diffenbaugh's method of prediction is not accurate enough to "add appropriate insight to be used by policymakers."

Christy, who's also Alabama's state climatologist, also distrusts localized forecasts. He told the Chronicle, "I would not base economic decisions on the output of regional predictions from these models."
One point I make in my book and here on this blog is that decisions to act are ultimately value judgments. While Pielke Sr. and Christy might not be moved to act based on a new scientific research, that does not mean that everyone shares their values. If I owned a bed and breakfast in VT and much of my business was based on tourists coming in to see the leaves turn every Fall, I'd be very concerned about changes in the New England climate, and might be spurred to act by this new research, even if others were not swayed.

Aged skeptics

I've noticed a pattern recently. Some of the most vociferous skeptics of AGW are professors emeritus. No doubt, some people will argue that these are the most trustworthy sources, since their career is over and they are not dependent on getting funding.

However, I will advance a second theory. I was at a meeting a few weeks ago where I ran into Bill Gray, a famous emeritus skeptic. He gave his standard stump speech in which he claims that the water vapor feedback is negative. I followed up on this with him and it became quite clear to me that he is unfamiliar with all of the peer-reviewed literature on this subject that has been published in the last five years. This makes sense. Reading the literature is a difficult and full-time job, and emeritus faculty simply don't need to do that. Especially (in the case of Gray) when your time is occupied being interviewed and screaming at people. As a result, my sense is that the views of emeritus skeptics are often substantially out of date.

But the story goes on. After arguing with him for a few minutes, it became clear that Bill Gray has no scientific theory of his own *why* the water vapor feedback is negative, and no data to support his non-theory. He has no manuscript describing his non-theory and no plans to attempt to publish it. After I pointed out all of the evidence supporting a positive feedback, he looked confused and finally said, "OK, maybe the feedback isn't negative, maybe it's neutral. I'll give you that." I quickly concluded that he has no idea what he's talking about. I wish everyone that considers him credible could have witnessed this exchange.

Thus, we have two explanations for the emeritus-skeptic phenomenon: 1) only they are credible because their career is over, vs. 2) their knowledge is substantially out-of-date. My personal experience is that the second explains the phenomenon far better than the first.

And anyone with additional theories, please leave a comment.

My point is not that all emeritus are out of touch with the scientific literature. Some continue to be extremely credible (anyone swinging at that strawman will have their comment unceremoniously dumped into the electronic ether). My point is that we have to consider whether any particular emeritus scientific (either pro or con AGW) is familiar with the most current science. If their knowledge is 10-years old, then their statements might be quite incorrect.

Monday, August 07, 2006

The one-percent doctrine

Take a look at this interesting article on action and uncertainty. Here is an interesting quote:
A companion to the Cheney 1 percent action doctrine (if the probability is at least 1 percent, act) is the administration's non-action doctrine (if the probability is less than 99 percent, then don't act). This latter doctrine is generally invoked in discussions of global warming, where it seems absolute certainty is required to justify any significant action. Ideology determines which of these two inconsistent doctrines to invoke.
As I've said here before, the threshold for action is a matter of values. We could pick any threshold we want for any problem. For climate change, my judgment is that, while we don't have certainty, we have enough evidence that a serious risk exists that we should take prudent action now.

Well said!

Take a look at this editorial in a recent Washington Post. The last paragraph makes a point that I've been trying to make for a while.

Sunday, August 06, 2006

Is today's warming man-made?

As George Bush said at a recent press conference: “the globe is warming. The fundamental debate: Is it manmade or natural.”

Why does the scientific community think that humans are significantly contributing to today’s warming? To understand why, first recognize that whenever the climate shifts, there’s a reason for it. It does not wander around like a drunken sailor.

Based on decades of research, we can write down the factors that have influenced climate in the past:
  1. Tectonic activity: The arrangement of continents plays an important role in determining the climate, and if the continents move, the climate might very well change.
  2. Orbital variations: The ice age cycles of the past few million years are driven by changes in the orbit of the Earth about the Sun. The Earth’s orbit has important variations with time periods of approximately 25,000, 40,000, and 100,000 years.
  3. Solar variations: The sun is the primary energy source for our climate. As the output of the sun changes, so does the climate.
  4. Volcanoes: They inject ash and aerosols into the atmosphere, which reflect incoming sunlight. A strong eruption can cool the Earth for several years.
  5. Internal variability: The climate system is complicated, and internal modes of variability exist. The most well known one is the El Nino/Southern Oscillation (ENSO). During the El Nino phase, the Earth is much warmer than during the opposite phase, the La Nina.
Finally, there is a new player in the climate game: human-emitted greenhouse gases. These gases trap upwelling infrared radiation, thereby causing increases in the temperature of the surface.

If we look at the warming of the last few decades, we can immediately rule out tectonic activity and orbital variations because they are much much too slow to account for the warming over a few decades. We can rule out volcanic eruptions for a similar reason --- they affect the climate for only a few years. Thus, volcanic eruptions are also likely unrelated to the several-decades long temperature increase we are experiencing.

We can rule out solar variability because we have high-accuracy measurements of the output of the Sun from satellites since the mid-1970s, and we have not seen the increase in solar output necessary to explain the temperature increase. This is not to say that solar is playing no role, just that it cannot explain the majority of the observed warming.

Internal variability is the hardest to evaluate. We know that ENSO significantly changes the Earth’s temperature, and so long-term ENSO-like variation is something that we have to consider. However, nobody has yet put forth a viable mechanism or shown data that such a long-term cycle exists. In the absence of any evidence supporting it, we conclude that it’s likely that internal variability is playing a minor role in today’s warming. Clearly, future research might cause us to re-examine this conclusion.

Finally, we have greenhouse gases. In this case, things work out well. Both the timing and magnitude of today’s warming are well explained by greenhouse gases.

This is why scientists conclude that humans are likely responsible for most of the warming of the last few decades. Greenhouse gases provide a reasonable explanation for the warming, while no other factor can explain the entire warming (other factors, such as solar, might be playing a minor role, however). In the IPCC report, they attach the word “likely” to the statement about the importance of greenhouse gases, which denotes about 75% confidence that the statement is true. This takes into account our imperfect knowledge of the atmosphere, in particular with regards to internal variability, and that future work might lead to revisions of our views of this.

Finally, note that this conclusion does not come solely from GCMs. Instead, it sits on a much firmer foundation of a range of peer-reviewed studies that use a wide range of techniques. One of the things that gives us confidence is that the studies all paint a consistent picture of today's warming.

Friday, August 04, 2006

Climate change on Lehrer Newshour

I've heard that the Newshour with Jim Lehrer (forever known to me as the McNeil/Lehrer Newshour) is likely(*) going to have a discussion tonight about climate change. This is probably motivated by the present heatwave. I've also heard that they're trying to get someone from the NAS Hockey Stick Panel to appear. I'll be tuning in.

[Addendum: They did not end up having any scientist on. Also, you can find a transcript and realaudio of the segment here.]

(*) Likely denotes confidence level of 75%

Wednesday, August 02, 2006

Is the science of climate change settled?

In the early 1990s, I worked on stratospheric photochemistry, i.e., ozone depletion. I even wrote a book about it (makes a great gift for that person who has everything!). By the mid-1990s, it was clear to me that the science of stratospheric ozone was truly settled. We understood just about everything. You know what I did? I decided to switch fields and study the climate system.

A constant argument in the policy debate over climate change is whether "the science of climate change is settled." It is clearly not. If it were, then I would have switched to another field, just as I did in the mid-1990s. No respectable scientist wants to do research on a system that's well understood.

However, everyone needs to recognize that we don't need perfect knowledge in order to take action. We make important decisions in the face of uncertainty all the time (e.g., should we invade Iraq?). In the case of climate change, we know enough to know that climate change carries a very real risk of severe, even catastrophic impacts over the next century. We can argue about the exact value of the risk: is it 20%, 50%, or 80%? I don't know the exact value, but it's not zero.

The decision about what to do about the uncertain risk of climate change is a policy decision and not a scientific result. How risk averse are we? Are we willing to trade some economic growth to reduce a risk of catastrophic climate change? This is something we have to decide as a society, and this is where the public debate needs to be.