Tag Archives: economics

Nate Silver falls off

In 2012, Nate Silver faced a conservative and media-led backlash for bringing rigor to election forecasting. His newly launched journalism project is now facing a backlash for failing to live up to its promise.

I am probably the ideal audience for Nate Silver’s new journalism project FiveThirtyEight.com. I am someone who values data in a frequently-substance-free world of reporting. Although I am an unabashed Sam Wang PEC partisan, I certainly appreciated Silver mainstreaming election forecasting based on factors other than wishful thinking and journalism biases towards “the horse race” and “momentum”. When Silver was attacked by know-nothings in the media and the conservative blogosphere, I cheered him on, and savored his election day vindication, anti-climatic as it was.

Rather than topping my “must read” list, however, the new FiveThirtyEight is something I won’t be reading. Here’s why:

I became aware of Silver’s imminent launch by his public Twitter announcement of two hires to cover science for his new venture: Emily Oster, a University of Chicago economist famous for counter-intuitive revelations (sound familiar?); and Roger Pielke Jr.

Image courtesy of Flickr user “ferdicam”, used under Creative Commons.

Now, I am not going to get into Roger’s pathological attacks on climate scientists. I am not going to get into his sweaty delusions of persecution. I am not going to get into Roger’s complete misunderstanding of elementary aspects of climate science. I am going to focus on just two things: what Nate Silver is known for, and what Roger Pielke Jr. is known for.

Nate Silver’s reputation is based on being a stats wiz. This is what his blogging was devoted to, what his best-selling book is about, and the one thing he has that his competition/peers like Ezra Klein or Matt Yglesias don’t. And one of Nate Silver’s very first, very public hires (Roger Pielke Jr.) sucks at statistics. Not “published something in need of minor correction once or twice” sucks. “Doesn’t understand how a t-test works” sucks. “Doesn’t understand basic probability” sucks. Sucks out loud. Sucks on ice.

Roger’s very first article for Silver’s new site is, unsurprisingly, about Roger’s hobbyhorse. The claim that disaster losses are not increasing due to climate change.

Let’s be clear about some things. Climate change is real. Humans are not just “contributing” to it, we are responsible for essentially all of it over the past several decades. Our perturbation of the climate through our emissions of greenhouse gases is fundamentally changing the Earth system. The biosphere and human systems are going to have to adapt to a rate of change as of now unseen anywhere else in the paleoclimatic record. In the absence of emissions stabilization, a difficult but decidedly achievable outcome, the threat to the biosphere and society is daunting. The amount of climate change we’ve already experienced, while extremely serious, is tiny compared to the impacts we will see in world of unchecked fossil fuel exploitation. In addition to changes in the average or mean state of the system, we have already begun to see changes in some types of extreme weather events, and changes to the drivers of yet other extreme events.

Ostensibly, Roger Pielke Jr. accepts all of the above. He just doesn’t want you to focus on this big picture. Instead Pielke wants you to believe and to focus on the claim that we’ve seen no increase in “normalized” damages due to climate change. The fundamental conceit of this claim is that even though disaster losses are unquestionably on the rise, once you account for changes in the value of infrastructure being built in areas affected by disaster (due to population growth, inflation, etc.), there is no “statistically significant increase”.

This claim rests on our ability to account for factors which might spuriously inflate the damages caused by disasters, but also our complete failure to account for factors that have allowed us to avoid even greater losses.

The case of 2012’s Superstorm Sandy is illustrative. While Roger spent the first few days of the disaster trying to play down the magnitude of the mounting carnage, Sandy ultimately ranked among the most costly storms on record, even using normalized losses. Preliminary estimates range from $50-65 billion USD.

And yet it could have been so much worse.

Hurricane Sandy uncharacteristically failed to recurve out to sea, and barreled back towards the East Coast of the US. Due to the amazing advances we’ve seen in our ability to model the global weather system, we knew well in advance that this unexpected turn by Sandy was a real possibility.

This possibility was taken into consideration by those trying to game out the impact of Sandy’s landfall. The impact of rising sea levels on the frequency and severity of storm surge flooding was as well. Looking to a future of warming-boosted surges, researchers identified huge vulnerabilities in the New York transportation infrastructure to previously rare events. Such considerations ultimately led the MTA to shutdown the subway system in order to avoid the corrosive impact of salt water if the tunnels were flooded. This decision, informed by modeling and meteorological sophistication unimaginable in the early 1900s, saved the subway system and prevented New York City from being paralyzed for weeks and nearly doubling the economic damages.

Image via Twitter

Roger Pielke Jr.’s “normalized” disaster loss fixation takes none of this into account. Nor does it account for the benefits of building code improvements. Or other disaster prevention measures like dikes.

Paul Krugman is among a growing list of knowledgeable folks who were hopeful about Silver’s new enterprise but are less than impressed. Krugman writes:

… data are never a substitute for hard thinking. If you think the data are speaking for themselves, what you’re really doing is implicit theorizing, which is a really bad idea (because you can’t test your assumptions if you don’t even know what you’re assuming.)

I feel bad about picking on a young staffer [Note: not Pielke Jr.], but I think this piece on corporate cash hoards — which is the site’s inaugural economic analysis — is a good example. The post tells us that the much-cited $2 trillion corporate cash hoard has been revised down by half a trillion dollars…

… what does this downward revision tell us? We’re told that the “whole narrative” is gone; which narrative? Is the notion that profits are high, but investment remains low, no longer borne out by the data? (I’m pretty sure it’s still true.) What is the model that has been refuted?

“Neener neener, people have been citing a number that was wrong” is just not helpful. Tell me something meaningful! Tell me why the data matter!

Though Krugman is referring to a different 538 article, he could easily be making the same criticism of Pielke’s. Why do Pielke’s data matter? Are disaster losses not increasing? They are. Does “normalizing” the loss data tell the whole, unbiased, story? No, it doesn’t. Are extreme events, and drivers of yet more extreme events, changing in response to GHG emissions? They are.

If Nate Silver’s mission is to bring statistical cachet to good journalism, he’s off to a terrible start. One of his first big hires is terrible at statistics. If Silver wants to tell us something meaningful instead of peddling freakonomics-lite contrarianism, he’s similarly off to a poor start. Pielke’s personal hobbyhorse obscures far more than it enlightens. It offers a cocktail party morsel of contra-conventional wisdom instead of intellectual nourishment.

There are probably a lot of people who would like to see Silver fail. I’m not one of them. I just won’t be one of his readers, either, unless he makes some big changes to his current model.

My apology to the field of economics

Image courtesy of Flickr user “Marie Laveaux”, used under Creative Commons.

I didn’t pay that much attention to Paul Krugman prior to about 2008- not coincidentally, around the time of the Great Recession and the bizarre situation wherein political decision-making seemed to be completely divorced from widespread consensus on action.

In any event, while I recognize that his political views are not everyone’s cup of tea, I have found his insider’s glimpses into the differences between economics as a mainstream discipline vs. economics as portrayed in the public arena by turns fascinating and maddening.

He recently offered this discussion, of the kinds of disagreements economists have within the discipline as practiced in good faith, vs. the disagreements with those shaping the public discourse in media [all emphases mine]:

So, what is neoclassical economics? … We imagine an economy consisting of rational, self-interested players, and suppose that economic outcomes reflect a situation in which each player is doing the best he, she, or it can given the actions of all the other players. If nobody has market power, this comes down to the textbook picture of perfectly competitive markets with all the marginal whatevers equal.

Some economists really really believe that life is like this — and they have a significant impact on our discourse. But the rest of us are well aware that this is nothing but a metaphor; nonetheless, most of what I and many others do is sorta-kinda neoclassical because it takes the maximization-and-equilibrium world as a starting point or baseline, which is then modified — but not too much — in the direction of realism.

This is, not to put too fine a point on it, very much true of Keynesian economics as practiced (leave aside discussions of What Keynes Really Meant and whether we’re all apostates). New Keynesian models are intertemporal maximization modified with sticky prices and a few other deviations (such as balance-sheet constraints). Even IS-LM loosely appeals to maximization arguments to derive the slopes of the curves, while analyzing outcomes by comparing equilibria.

Why do things this way? Simplicity and clarity. In the real world, people are fairly rational and more or less self-interested; the qualifiers are complicated to model, so it makes sense to see what you can learn by dropping them. And dynamics are hard, whereas looking at the presumed end state of a dynamic process — an equilibrium — may tell you much of what you want to know.

That sounds remarkably like any kind of modeling in systems sciences. I was thinking physics/oceanography/climate, or ecology, but Krugman follows through on this idea with an analog he’s cited before:

These motives are the reason why other fields facing similar concerns adopt similar strategies. As I wrote long ago, evolutionary theory — the biological kind — looks remarkably like neoclassical economics.

Indeed.

Hearing Krugman lay out the pretty reasonable basis that modern mainstream economics starts from, I wondered to myself just how I came to think so poorly of the field. And the answer of course was economists and economic pundits making absurd claims across all manner of media.

And Krugman cuts to the heart of that:

They claim to reject neoclassical economics, but their alternative is not an alternative model but a lot of verbiage; they talk at the economy, and imagine that by so doing they achieve a higher level of sophistication and realism than economists who try to express their ideas in terms of little models.

And they’re kidding themselves; all they’ve done is hide their implicit models and prejudices behind a dust cloud. And that’s one reason they have been so disastrously wrong at every stage of this crisis.

The economists that I was so disgusted by were not ones who simply used mainstream or even alternative models and arrived at conclusions that differed from my preferred outcomes- they were talking heads from the Wall Street Journal, doom mongering on Glenn Beck’s clown show. They pretended to be speaking plain truths that didn’t rely on “suspect” models, but of course were using models of their own- laughably unconstrained by reality, internal consistency, or the body of evidence of their field.

Sounds all too familiar, doesn’t it?

Imagine if the field of climate science was judged by the talking heads or blogologists who eschew physics-based climate models as fraudulent, perversely talk about how a warmer MCA means we have nothing to worry about from unchecked increases in radiative forcing, or make endless predictions of cooling just around the corner that never come true.

Whether or not mainstream economics ultimately contends with the biogeochemical limits of a finite system, I shouldn’t judge it against the worst of its mouthpieces.

Roy Spencer reveals his motivation for rejecting the climate mainstream- not science issues, but economic concerns

Image courtesy of Flickr user "SarahDeer", used under Creative Commons

Straight from the horse’s mouth, emphasis Spencer’s:

[Washington Post reporter Juliet Eilperin] provided several paragraphs alluding to why scientists on the [mainstream] side of the issue speak out, but nowhere could I find reasons why WE [i.e. the contrarian minority] speak out.

I had told her that ill-conceived energy policies that hurt economic growth kill poor people. Was that not a sufficiently interesting thing to report on?

I guess after a while, even ostensibly serious “skeptics” like Spencer forget that they’re supposed to pretend they’re arguing science instead of a whacked out, far right wing, “economic” ideology.

Although probably unnecessary, it might be worth pointing out that actual economists think that delaying action on climate change will hurt more than using “cheap” fossil energy will help.

“Cool It” yourselves

Since it looks like it’s going to be wall-to-wall Lomborg in the press for a while, it’s probably worth reviewing why he is not only not taken seriously by many people actually concerned about climate change, but why a great many people actively dislike him. It’s not that he proposes “alternatives” to mitigation efforts like cap-and-trade, although he would certainly love for people to believe that.

It’s because he presents himself as someone credible, someone who isn’t a climate denialist- i.e. he proclaims to accept the reality of anthropogenic warming and to consider it a serious threat. But as anyone who has dealt with denialism knows, few if any people in the grips of denialism actually consider themselves to be denialists. There are plenty of “intelligent design” proponents who claim not to reject biology but rather believe that key aspects of evolution are overstated (e.g. irreducible complexity). Many anti-vax denialists claim to support vaccines but only want to “make them safer/greener”.

It’s not so much what someone professes to believe that determines whether or not they’re engaging in denialism, but the way they misrepresent evidence.

And Lomborg has quite a history of doing just that. Let’s take a look at just three such cases:

On polar bears:

Lomborg has frequently and grossly misrepresented scientific data and literature on polar bears and other aspects of climate change.

He has claimed that the Arctic Climate Impact Assessment says polar bears have nothing to worry about, they’ll just devolve into brown bears:

The Arctic Climate Impact Assessment finds it likely that disappearing ice will make polar bears take up “a terrestrial summer lifestyle similar to that of brown bears, from which they evolved.”

The implication is that polar bears aren’t actually threatened by (anthropogenic warming-induced) sea ice decline, because they can just go back to acting like brown bears and everything will be fine. It sounds ludicrous, so much so that an an interviewer for Salon.com asked Lomborg if that is actually what he was claiming. Lomborg made it crystal clear that it was, and that it was his genuine understanding of the Impact Assessment report:

Salon: Are you saying that polar bears will be OK, that the species will survive if they evolve backward?

Lomborg: Yes, that’s certainly how I read it.

But the Impact Assessment said no such thing. Sea ice decline presents a dire, possibly fatal threat to polar bears. In a summer ice-free Arctic, there is no “okay” scenario. Polar bears face demise or might eke out a grim survival among threats from other species of bears and humans. The Impact Assessment states:

It is difficult to envisage the survival of polar bears as a species given a zero summer sea-ice scenario. Their only option would be a terrestrial summer lifestyle similar to that of brown bears, from which they evolved. In such a case, competition, risk of hybridization with brown bears and grizzly bears, and increased interactions with people would then number among the threats to polar bears.

Far from representing a scenario in which polar bears are “okay” living like brown bears, the Impact Assessment presented it as a last hope, fraught with major threats of its own.

In good company with many other climate denialists, Lomborg has also tried to give the impression that polar bears aren’t really in danger from anthropogenic warming because their populations are increasing, not decreasing.

He does by citing historic population levels at 5,000 in the 1960s and present numbers at 25,000. He conveniently omits population estimates that put historic numbers at 18,000-20,000 and the present numbers as low as 20,000. In other words, given the spread of the estimates, it’s possible to cherry-pick numbers that give you anything from no increase whatsoever, to a modest increase, to a monstrous increase of 20,000 bears. Lomborg chooses the latter, without justification for doing so or informing his audience of the full range of estimates.

But suppose we ignore this blatant cherry picking. According to Lomborg’s numbers, had polar bears been recovering from a low brought about by unregulated hunting? Yes. Does this recovery mean that they aren’t threatened by global warming? No.

Or, characterized this way by UCN/SSC Polar Bear Specialist Group Chair, Andrew Derocher:

The various presentations of biased reporting ignore, or are ignorant of, the different reasons for changes in populations. If I thought that there were more bears now than 50 years ago and a reasonable basis to assume this would not change, then no worries. This is not the case.

The bottom line here is that it is an apples and oranges issue. The early estimates of polar bear abundance are a guess. There is no data at all for the 1950-60s. Nothing but guesses. We are sure the populations were being negatively affected by excess harvest (e.g., aircraft hunting, ship hunting,self-killing guns, traps, and no harvest limits). The harvest levels were huge and growing. The resulting low numbers of bears were due only to excess harvest but, again, it was simply a guess as to the number of bears….

Comparing declines caused by harvest followed by recovery from harvest controls to declines from loss of habitat and climate warming are apples and oranges. Ignorant people write ignorant things.

Derocher is saying that such claims (even granting their numbers) are at heart a combination of two forms of fallacious reasoning, the cherry pick (polar bear populations are increasing during a certain interval) and the non sequitur (therefore they are not threatened by anthropogenic warming). The claim that polar bear populations are rising only holds true because the period is selected to begin at a low point brought about by unregulated hunting. Once hunting restrictions were put in place, populations had begun returning to their historic norms.

However, that does not mean that polar bear populations are increasing across the board. The IUCN Polar Bear Specialist Group found in 2005 (well before the 2007 publication of “Cool It!”) that of the 19 polar bear subpopulations, only 2 were increasing, while 5 were flat and 5 more were actually in decline (there were insufficient data for the remaining 7). Relative to their historic levels, only 6 subpopulations were believed to be “not reduced” while 6 were “reduced” or “severely reduced” (there were insufficient data for the remaining 7).

(In case anyone is curious, in 2009 the IUCN Polar Bear Specialist Group found that only “1 of 19 subpopulations is currently increasing” while “3 are stable and 8 are declining” with insufficient data for the remaining 7.)

Lomborg does not appear to have corrected or retracted his claims.

[Edited to add: this of course doesn’t even get into the discrepancies between Lomborg’s “don’t worry” attitude and the scientific literature on projected polar bear population trends as sea ice declines. I may add that in later.]

On sea level rise:

Lomborg also has a nasty habit of claiming that sea level isn’t rising as fast (or at all!) as mainstream climate science believes. To do so, he picks whichever start and end points he can to get the smallest trend in sea level rise.

Writing in the Guardian in March 2009, Stefan Rahmstorf exposed Lomborg’s cherry-picking as the dishonest misrepresentation that it was:

Why does Lomborg cite the trend [2005-2008 1.6mm/year]? Last October, he cited that of the previous two years. Why now four years? Because the trend of the past two years (2007-2008) is now + 3.7 mm/year? It is even worse. The trend since the beginning of any year of the data series varies between 1.6 mm/year and 9.0 mm/year, depending on the start year chosen. Using 2005, Lomborg cherry-picked the by far lowest.

Sound familiar? This kind of dishonesty is all the more reprehensible because Lomborg is (was?) an associate professor of statistics! This isn’t the naive error of someone acting in good faith, it’s entirely, despicably deliberate.

On Global Temperatures:

In much the same way that Lomborg is fond of misrepresenting polar population dynamics and sea level rise, he also enjoys misleading the public about global warming’s most well-known symptom: rising temperatures. It’s occasionally claimed that while there is political disagreement about what to do about global warming, no credible scientist or policy wonk actually doubts that the planet is warming. Judging by surveys of scientists and statements by various governmental organizations, that’s probably broadly true.

And then, there’s Lomborg:

It is hard to keep up the climate panic as reality diverges from the alarmist predictions more than ever before: the global temperature has not risen over the past ten years, it has declined precipitously in the last year and a half, and studies show that it might not rise again before the middle of the next decade.

This was Lomborg writing about cooling back in 2008, as we were experiencing a fairly strong La Niña. Cooling! No warming since 1998! Claims at home in the comments section of the most ignorant and paranoid of climate denialist blogs (or George Will columns).

Most people relatively conversant with major features of the climate system, let alone “climate experts” holding international conferences and writing books on the subject, are aware that La Niñas don’t equal global cooling. In case there was some confusion about the La Niña and the appearance of a lack of warming among the general public, climate institutions like Met Hadley and others had handy pages explaining that, no we weren’t cooling several months prior to Lomborg’s claim.

Lomborg (like other denialists) was simply taking one slice of time (1998-2008) out of a much larger data set- without any attempt at justification- to get the results he wanted- results in complete opposition to what a serious examination of the data would show, requiring an ignorance of basic physics, meteorology, and statistics to believe.

A Question for Journalists:

What is it about Lomborg that allows you to engage in collective amnesia about his dishonesty? Have you forgotten that people like Kåre Fog and Howard Friel (not to mention the blogosphere) have exposed him for what he is?

Did Lomborg really change his delayer tune?

Way back in July of 2008, I wrote this about Bjørn Lomborg:

Lomborg, similarly to Michael Shellenberger, Ted Nordhaus, and Roger Pielke, Jr. is not actually a climate change denier per se- he claims to accept the underlying principles whereby anthropogenic emissions warm the planet and alter the climate, though he often underplays or otherwise attempts to minimize the expected impact- rather these “non-skeptical heretics” argue against emissions regulation policies and instead push for increased investment in future technologies, which presumably will come to fruition at an unspecified later date that will arrive in time to prevent the most severe negative consequences otherwise expected…

You can be guaranteed that the take home message from Lomborg at the end of the day will be “delay, delay, delay” [pricing and reducing emissions] “because technology, technology, technology”.

Has Lomborg changed at all? Lomborg was recently (21/9/10) interviewed by New Scientist, in a piece headlined: “Bjørn Lomborg: Use technology to fight climate change“. He argues for the same in an op-ed in the Australian earlier this month:

Galiana and Green find that devoting just 0.2 per cent of global GDP, about $US100 billion a year, to green energy R&D would produce the kind of game-changing breakthroughs needed to fuel a carbon-free future. Not only would this be a cheaper fix than trying to cut carbon emissions, it would reduce global warming much more quickly.

There is no currently available “breakthrough” energy technology, nor is one on the horizon. Banking on this myth is like betting that you don’t have to have a fire evacuation plan for your office because you hope to ride a unicorn out of the burning building.

The “breakthrough” needed to develop cost-competitive alternatives to fossil fuels is to actually price in the negative externalities from carbon-intensive fuels, in order to let the market most efficiently determine the “winning” substitutes. This is basic, market-based economics. Funny how the “alarmist” greenie commies are the ones that constantly need to point this out, isn’t it?

Debunking Jim Manzi in 5 Easy Steps

Via Michael Tobis, it seems that Jim Manzi is generating a bit of buzz for a non-denialist challenge to the case for mitigating climate change recently published at TNR: Why the Decision to Tackle Climate Change Isn’t as Simple as Al Gore Says.

First off, let me echo others who’ve stated that it’s a pleasure to engage with someone who doesn’t typically deal in the fringe, anti-science nonsense that dominates so much of the right in American political discourse. To his credit, Jim Manzi doesn’t attempt to de-legitimize the scientific basis of anthropogenic climate change and chides his conservative colleagues for exactly that sort of tinfoil hattery.

With that said, it’s disappointing to see Manzi engaging in an only slightly less silly argument against mitigation, which utilizes a superficial gloss on some figures from the 2007 IPCC WGII Summary for Policy Makers to propose that costs incurred from unchecked warming don’t justify the cost of preventing it. This is an argument Manzi has made before in other venues, and one I’ve engaged him on previously.

Manzi’s argument can be fairly summarized as “according to the IPCC, the most warming we can realistically expect is 4°C, which will only cost ~3% global GDP using economic models like DICE, which is less than mitigating against that warming will cost according to an analysis of my choosing, ergo mitigation isn’t an optimal strategy”.

  1. There is only one SRES scenario that reasonably tracks real world emissions growth per observations and infrastructure legacy: A1FI.
  2. The “likely” temperature range for A1FI is 2.4-6.4°C.
  3. The high end cost of ~6°C warming in Manzi’s source is upwards of 11% global GDP, yielding a range/estimate of 1-11%/5.5% GDP, not 1-5%/3%.
  4. Manzi cites a third party estimate of mitigation costs as ~6% GDP for stabilization at 450 ppm, while other analyses by experts in the field put the cost far lower- e.g. 2.5% at 350-400 ppm.
  5. Being generous and more than splitting the difference- rather than using my own preferred analysis outright- gives a cost of 4.25% GDP for 450 ppm, compared to a non-stabilization cost of 5.5%GDP.

In short Manzi’s analysis depends on a suspiciously narrow reading and selection of source material that doesn’t hold up to even a cursory amount of scrutiny.

Further points: This simple debunking has ignored other problematic assumptions implicit in Manzi’s analysis- the absurdly conservative damages of the DICE model, for example. Notoriously, DICE shows a warming of 20°C resulting in a loss of only 50% of global GDP, a warming so extreme that it would exceed humans’ (and other mammals’) capacity to endure heat stress, resulting in mass extinction. It’s fairly safe to say that there wouldn’t even be a “Gross Domestic Product” much less one half as large as today’s 2100’s expected. Ocean acidification, non-linear ice sheet collapse and resulting sea level rise, and other costly consequences of unchecked emissions are likewise ignored by DICE. [And yes, I realize that Manzi will simply claim that the IPCC deserves a similar criticism, with which I agree- though in its defense the IPCC doesn’t attempt to hang its conclusions on such a slavish acceptance of this modeling.]

Work by others (like Annan and Hargreaves) finds losses from DICE to be understated in the AR4 compared to their own papers. This isn’t a problem with Manzi’s formulation of the issue, but is relevant to the discussion.

On a final note, it’s also disappointing  to see that the pro-mitigation punditry (e.g. Klein, Plumer) don’t even appear to seriously investigate Manzi’s argument, but rather grant his flawed premises and hand-wave in favor of mitigation anyway. Or as Tobis puts it (emphasis in the original): “The answer from the punditry to Manzi is not to call the absurdly small cost into question, but to say that we should take drastic action anyway, even though the [economic] risk is trivial.” As much as I appreciate the interest of Klein and Plumer in climate issues, they do not appear to be sufficiently conversant with the relevant material to proficiently engage their opposition.

A1FI1

Who’s calling who an “alarmist”?

One of the more common memes heard from the self-styled “skeptics” is that we should not “wreck the economy” by attempting to reduce greenhouse gas emissions through programs like cap and trade or a carbon tax, based on “alarmist” predictions. Implicit in this assertion is that there is solid economic justification or at least a consensus among economists that a cap and trade solution should not be pursued.

A consensus among economists does, in fact, exist. Just not the consensus the denialosphere would like people to believe.  Earlier this week, J. Scott Holladay, Jonathan Horne, and Jason A Schwartz from NYU’s Institute for Policy Integrity published a survey of economists on climate change entitled “Economists & Climate Change: Consensus and Open Questions.” Their findings support an under-reported piece by Eric Pooley from early this year about the failure of the media to accurately convey the economic position on mitigation.

Key findings:

The survey found consensus on several key questions:

  • Climate change poses risks to the U.S. and global economies;
  • Several domestic economic sectors, most notably agriculture, will be negatively affected;
  • Uncertainty about climate change increases the value of action;
  • The United States should adopt market‐based mechanisms for reducing emissions, those mechanisms will create incentives for efficiency and clean energy, and allowances should be auctioned rather than given away; and
  • The United States should join a global regime to reduce emissions, with a majority of economists saying the United States should commit to emissions reductions regardless of other countries’ actions.

The survey also found that there is no consensus that the future costs and benefits of climate change policy should be discounted at a constant rate, with an equal number saying that alternative discount methodologies should be used, and a significant percentage stating that alternative moral inquires were the most appropriate way to approach intergenerational questions.

That last bit is striking. There are those who fancy themselves non-denialists who oppose mitigation on economic grounds based upon narrow readings of economists like Nordhaus- Jim Manzi comes to mind. Manzi and others’ argument against action essentially hinges on the discount rates assumed, portraying their analyses’ choices as mainstream. This survey reveals that rather than being mainstream, there is no consensus on Nordhausian let alone constant discount rates, and those favoring non-constant rates discounted the cost of climate change at a substantially lower rate (i.e. more heavily favoring expenditure now rather than passing the costs off to future generations).

The third finding listed above, though, is the one that needs to be driven home to policy makers. Politicians are fond of stating that they need more certainty before they are willing to get on board with mitigation efforts, while economists overwhelmingly conclude the opposite- uncertainty increases, rather than decreases, the value of mitigating now.

So the next time someone accuses you of being an “alarmist” who is willing to destroy the economy over emissions reductions, feel free to direct them to this report. And while you do so, let them know that they’re the real “alarmists”.