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 grist.org. 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 grist.org 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 dodgeit.com 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)