Climate Update

[marcusmarcusrc]

The summary for policymakers of the IPCC Fourth Assessment Report (the biggest climate document of the last five years, both in size and importance) was just released today.

"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations."
Two nice graphs: pg. 16 (SPM-2): Forcing changes since 1750: Anthropogenic contributions: 0.6 to 2.4 W/m2 (uncertainty mainly due to interactions between aerosols and clouds). Change in solar forcing: 0.06 to 0.3 W/m2. pg. 18 (SPM-4): Comparing models run with "just natural" forcing and "all forcings" to observations, showing how the last half century of warming is not explained without human influences. (this is a qualitative comparison: there are of course more quantitative measures of attribution behind this)

For the most part the report attempts to put probability ranges on all the reported numbers (rather than just reporting ranges, as in the third assessment report).

Projected temperature change for the next century: 1.1 to 6.4 degrees C (without probability, since they still don't quantify probabilities for emissions scenarios) (compare to 0.6 degrees C for 1900 to 2000). Sea level rise: 18 cm to 59 cm (compare to about 17 cm for 20th century). This does not include Greenland/Antarctica, which could add another 10 to 20 cm or more, but the melting processes of these ice sheets are still poorly understood.

It is also "likely" that we will see both more droughts and more heavy precipitation events, and more intense tropical cyclones in the 21st century.

Discussion also available at realclimate.

Note that the summary is based on a report that is fully drafted but "embargoed", and will not be released until April. The science in the full report is set, and won't change, but there may be minor edits and wording changes. The summary itself still needs some editing (I've noticed a few typoes), but apparently once it was "hammered out" by scientists and politicians to be as understandable as possible while still accurately reflecting the draft chapters they wanted to release it as quickly as possible.

Note that it seems like most people think that this report has been somewhat "conservative" in its statements.



In other climate news, Prof. Lindzen of MIT appeared on Larry King along with Bill Nye the science guy. Sadly, in the short clip I watched (the first couple minutes of the show), Lindzen repeated one ridiculous skeptic canard, namely "it hasn't warmed in the past 8 years" because 1998 was as warm as any year since. Claiming that this indicates that there isn't a warming trend makes about as much sense as saying on June 8th, "hey, it was warmer on June 1st than it is today. Therefore, there isn't a warming trend! I bet it won't be any warmer in August than now!" Lindzen is probably the best scientist among the "climate skeptic" population, but this kind of statement among others is why I've lost any respect for him. It is also odd that a 4 person panel would consist of 2 "skeptics" and 2 "mainstreamers" where the skeptics are a climatologist and an economist and the mainstreamers are a weather channel host and a TV science guy - why didn't they get a mainstream scientist or economist on the show? Why did the show have to "evenly represent" two sides of view that are totally not evenly represented in the real world? etc.

Comments

[marcusmarcusrc.livejournal.com]

They also get to talk about "how much will the weather changes that these guys are talking about cost us?" Which they can then compare to "how much would it cost to avoid these changes". In fact, the full report will eventually have 3 portions: 1 on science, 1 on economic impacts of change and adaptation, and 1 on economics of reducing emissions.

In this case, the economist on the show was reasoning "since we project that incomes will be much larger in 50 or 100 years, why should we cut consumption now to help them out? They're rich! They can take it."

(mind you, this isn't _entirely_ faulty reasoning, just... way oversimplified)

[kirisutogomen.livejournal.com]

Well, it's TV. Of course it's oversimplified. Plus I bet you just oversimplified his oversimplification. In its detailed form it's actually pretty convincing.

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The thing where you have each side equally represented (even if one side is mainstream and the other is lunatic fringe) is standard journalism. Apparently journalism school doesn't explain the difference between "objective" and "balanced." Of course, objective reporting is likely to be boring, while balanced reporting is always exciting, because you can always get a fight going.

(Oh, and you can be annoyed with "it hasn't warmed in the past 8 years" if you can get your supporters to stop claiming that every unusual weather event is due to climate change.)

[marcusmarcusrc.livejournal.com]

In its detailed form, it still leaves a lot to be desired, in my opinion.

1) The mean, and even the median, income in the world will indeed most likely increase significantly. I'm betting that there will still be hundreds of millions of people living in poverty by any standard, however, unless our ability to distribute wealth improves. If I could somehow be convinced that money not spent on emissions mitigation was actually going to go towards improving their standard of living then I might be convinced of the rest of the argument... or if I was convinced that mitigation efforts would lead to economic collapse... but I'm not. And therefore I think that in fact there are significant human welfare reasons to take climate change mitigation steps now even in the face of discounting and GDP growth.

2) As GDP grows, the value placed on certain ecological services will also grow a lot. Coral reefs and polar bear habitats aren't so replaceable, and how much will a society with a median income of $100,000 value them at?

3) This is the sort of logic that one could have used 50 years ago for toxic waste dumping and leaded gasoline, etc. But as our understanding of the impacts grow, and our valuation of health increases, we realize that for a small cost of abatement then they could have saved ridiculous costs of cleanup and health damages now.

Having said all that, I do think that one does need to discount the future, in large part because of this income growth. However, one also needs to discount future mitigation costs in the same way. Very few people are suggesting $1000/ton carbon taxes today. We suggest small taxes (or equivalent policies) now, and may be suggesting such large taxes (or higher) in 2100. etc. etc.


And I can perfectly well be annoyed with an _MIT Professor_ using the "it hasn't warmed in 8 years" illogic. I will point out that none of the climatologists I know would get up and say "wow. Warm winter this year. Must be global warming." I admit that the hurricane experts will mention Katrina, but will immediately follow it with "no single event can be attributed blah blah blah". I expect higher standards from people who expect to be respected as real scientists than from, say, Greenpeace activists or oil company lobbyists.

[kirisutogomen.livejournal.com]

The distribution is irrelevant. We're not suggesting that the poorest people in the world pay the mitigation costs in the present, and we won't expect them to pay them in the future either.

That said, while there will probably still be people in poverty in 50 years, I don't expect there to be anyone in poverty in 100 years. This depends strongly on things like our current response to HIV in sub-Saharan Africa, though. To the extent that present expenditure on carbon abatement reduces expenditure on HIV abatement, I think we're serving the poor of today and the poor of tomorrow badly. In a perfect world, we'd do both.

More generally, overall economic growth is distributed fairly evenly over the time periods we're discussing. So as long as money not spent on emissions mitigation isn't being fed into bonfires, it is going towards improving the standards of living for the very poorest.

Your point 2 is very tricky to deal with rigorously, but I suspect ultimately that while you're correct, the magnitude of the other costs is so much greater that it doesn't matter.

Your point 3 is a little silly; sure, if we'd understood the impact better 50 years ago, we would have chosen differently, but we didn't. Similarly, maybe in the future we'll discover that back in 2007 we were grossly underestimating the long-term effects of climate change. But maybe we'll discover that we were grossly overestimating them, or that we were grossly underestimating the health benefits of rapid economic growth, or whatever. We have to make the decision with the best information we have right now, not with some wild guess.

I think you're being a bit disingenuous about what people are suggesting in terms of carbon taxes. I've certainly seen the figure of $300/ton in the immediate future. (I wish I could remember where, because I hate throwing a number like that out without citation.)

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Yeah, you're absolutely right about it being different for an MIT professor to say something irresponsible like that.

I can imagine that being in a situation where one is being placed on an equal footing with Bill Nye The Science Guy and a TV weatherman could cause one the sort of emotional pain that you feel when Congress pays attention to Michael Crichton. I can further imagine that being placed in that position could tempt one to stoop to those sorts of tactics. I don't think that justifies it, but I can kind of see how it might happen.

[marcusmarcusrc.livejournal.com]

Honestly, I have a very hard time imagining a world with 10x the current average GDP, so it makes it difficult for me to evaluate tradeoffs accurately. My gut feeling is to be cynical and assume that much of Africa will still be dirt poor, as well as decent chunks of Latin America and SE Asia.. but I acknowledge that I could be very wrong. I do admit that with some exceptions, the poor in the US have a standard of living much higher than they would have had 100 years ago (at least, as measured by access to things/services, or health/lifespan). But if the rest of the world can really reach US/European standards of living in 100 years, which our economic models or extrapolation of average GDP growth predicts.. well... that would be something. Of course, Africa has averaged 0.19% GDP growth since 1973, compared to 1.4% for the world average... so obviously there has been historical growth discrepancies. And despite the general consensus of my colleagues and other economists, I sometimes wonder how GDP can continue to grow at such a high rate (and for example, worldwide GDP growth in the 50s and 60s was 2.9%, so is the slip from 2.9 to 1.4 a trend or a fluctuation?)(GDP #s from Maddison, 2001)

Oh. And the distribution _is_ relevant, because while the poorest people don't directly pay mitigation costs (I admit they pay some indirectly) they do suffer from climate change. In fact, poor Bangladeshis living on a flood plain are expected to suffer disproportionately from sea level rise and changes in precipitation patterns. Ditto for African subsistense farmers.

Also, the assumption that money not spent on emissions mitigation will almost automatically lead to improved standards of living for the poor - I'm also dubious. Yeah, it is standard economics of limited resources, but... I can see a lot of areas less worthwhile than climate mitigation that we could choose to shift money out of, and that in fact I feel like money we don't spend on climate mitigation is as likely go into those areas as into HIV prevention. Also, I feel like even ignoring the climate externalities, that there are a lot of economic distortions in energy production/use that lead society to use more energy resources than would be otherwise optimal... but that's again more gut instinct than hard numeric analysis.

We know that we are making significant changes to the environment with unknown impacts. When sticking long-lived chemicals into the environment, whether it be PCBs, CFCs, or GHGs, where low cost abatement measures exist we should be taking them because we _can't_ test all the possible impacts. Our best estimates of climate change involve a lot of bad but not catastrophic outcomes in the next 100 years. But there are potentials for certain tipping points (precipitation feedback loop in the amazon, melting of the greenland ice sheet) that are unlikely (well, greenland is likely on a long time scale, unlikely on less than 200 years) but would be impacts of disastrous magnitudes. If we do exceed 5 degrees celsius increase on the 100 year time scale (I'd estimate a couple percent chance) I think it is likely that that temperature increase will be accompanied by some unforeseen disastrous change because we're talking about a temperature change of the magnitude of glacial/interglacial shifts, and at extremely high rates.

And I still don't know how we value coral reefs. It is likely that they'll suffer a lot in any but the most optimistic scenarios - but how much HIV prevention is saving the coral reefs worth? Are we talking about their value as part of the larger oceanic ecoystem? Or their existence value? Or their tourism value? Or what? Is their existence worth a billion dollars? (surely it is) A trillion dollars? (I'd think so, but I don't know) A quadrillion dollars? (probably not...) Of course, even "just" a billion dollars is a lot of HIV prevention, and it is hard to say that "these coral reefs are worth hundreds of thousands of human lives" (though if loss of the coral reefs led to collapse of fisheries, then their loss might indeed lead to a loss of many thousands of lives). And a billion dollars is also less than a single stealth bomber, and I think a coral reef is worth many, many, many stealth bombers.

[kirisutogomen.livejournal.com]

Also, the assumption that money not spent on emissions mitigation will almost automatically lead to improved standards of living for the poor - I'm also dubious. Yeah, it is standard economics of limited resources, but... I can see a lot of areas less worthwhile than climate mitigation that we could choose to shift money out of, and that in fact I feel like money we don't spend on climate mitigation is as likely go into those areas as into HIV prevention.

You have to be realistic about your assumptions regarding where the money is going to come from. Sure, in a perfect world we'd shift money out of reality TV and into climate mitigation, but those are actually two very distinct decisions. Emissions abatement is in practice just going to act as a general drag on economic activity, with a bias toward energy-intensive activity. So yeah, not much is going to come out of HIV prevention, but nor do you get to pick some especially egregious expenditure and say, hey, let's take the money from there. In general, the poor participate approximately equally in economic growth, and emissions abatement has approximately proportional effect on economic growth.

Less generally, the extra impact on energy-intensive economic activity tends to disproportionately impact the people who rely on agriculture and low-tech manufacturing, i.e., the poor. Unless of course we exempt India and China from GHG reductions, in which case we're getting the worst of both plans -- lower economic growth plus global warming.

Anyway, yeah, the thought of what the world is going to look like with a $100,000 GDP per capita is pretty mind-boggling, but I seriously expect it. I also won't attempt to explain how, any more than I would have recommended to someone in 1907 to forecast what the structure of the global economy would look like over the ensuing 100 years.

What's the long-term trend rate of growth? Who the hell knows? 2.9% sounds more reasonable than 1.4% to me. Maddison's date of 1973 is kind of a breakpoint, as you know. (FWIW, GWP grew at 5.1% last year and 4.4% the year before.)

And as far as comparing coral reefs to HIV prevention and stealth bombers, I just refer back to what I started with. You can't make up a scenario where you take money from the bombers and give it to the reefs, because those are two separate decisions. If you want to value the coral reefs, you have to do so in terms of money, because that's the only reasonable metric. If you think stealth bombers aren't worth nearly as much as they cost, that's a statement about bombers, not about coral reefs.

[marcusmarcusrc.livejournal.com]

On carbon taxes: if we look at CCSP product 2.1 (http://www.climatescience.gov/Library/sap/sap2-1/public-review-draft/sap2-1Aprd-chap4.pdf), 3 different models came up with carbon taxes in 2020 of $90 to $260 in order to be on a path to 450 ppm stabilization (which is considered to be an ambitious target). And those are global, so if we were to do Annex B nations first and non-Annex B later, maybe your $300/ton isn't that far off for a near term tax in the OECD in order to achieve ambitious targets. Of course, $300/ton is 75 cents/gallon on gasoline, or 5 cents/Kwh on electricity...

(for comparison, I think the European Trading System carbon price peaked at about $100/ton, and is back down to less than $10/ton now. I _so_ wish I could have figured out some way to make money off the fact that everyone in my lab was 90% certain that the $100/ton price was totally off base)

Anyway, to sum up: I really do think it is worth spending some significant but not economy-crushing amount of resources on emissions mitigation now in order to reduce climate impact in the future, despite projected economic growth of possibly unimaginable magnitude. Of course, I admit that given that I've chosen to spend the last N years studying the topic, it would be hard for me to reach the conclusion that those N years were wasted because the climate problem isn't worth worrying about... but I'm trying to be as rational and unbiased as I can manage...

[kirisutogomen.livejournal.com]

See, it's great. I randomly spew numbers without citation, and you go look it up for me. I should do that all the time.

I tend to agree with you in the broadest sense, that we should be doing something about climate change. I think the only reason I started debating at all was because it sounded like you were being a bit flip about the idea of discounting. I expect it sounds a bit silly on TV, but most things do.