Some authors, such as the Viscount Matt Ridley, like to claim that Climate Change (CC) will be beneficial. Ridley uses a well known figure from Richard Tol's 2009 meta-study of 14 papers on the economic effects of CC to claim that there is a net benefit up to 2C. The Bishop has printed this graph several times, including recently here. All but 2 data points on the graph show near-zero or negative effect of climate change. And one of the two positive points later turned out to have had its sign reversed by Tol. The best-fit curve in the graph is significantly positive above 2C thanks to these two data points. Ridley's use of this graph to claim net benefit from CC seems foolish.

In 2014, Tol updated his 2009 paper after errors were pointed out. At the same time he added five newer data points to the graph. The new graph has 21 data points (some papers gave 2 estimates). As in the Tol 2009, 2 points (from Mendelsohn et al 2000) show 0% and 0.1% effect at 2.5C warming but all of the rest except for one from Tol 2002 show negative effect. The best fit curve in the graph now remains below zero with no net benefit from warming.

Would it surprise you to learn that Viscount Ridley still claims that climate change will have a positive effect up to 2C? He still in 2015 uses Tol 2009 to make this claim despite the errors and changes to Tols paper having received wide coverage.

Bishop Hill has presented the famous graph from Tol 2009 several times, including in the link above, but as far as I am aware has never published the corrected graph (which can be found here). Maybe the thinking is that nobody wants to know.

Tol has a new working paper where he rehashes all of this once again and shows a different best-fit, this time using piece-wise linear best fit. Again this has had errors, including the same reversed-sign point at 2.5C (see here) and Tol has contrived a "best fit" that once again shows net benefit at 1C (unchanged with or without the reversed sign point at 2.5C). So is Ridley safe to claim net benefit now?

The thing about the graph in Tol 2009 and the new one in the working paper is that the peak benefit is at 1C above pre-industrial, which we have now reached. Any benefit that Ridley will doubtless go on claiming is based solely on one of 21 data points, that from Tol 2002. An even if you accept this one-in-21 study as outweighing all the negatives, the benefit is already baked-in now. From now on, it is all downhill with net harm all the way. Yet Ridley will claim net benefit all the way to 2C.

Of course, all of these studies are of academic interest only. It seems laughable to expect an economic model to be able to predict the outcome of climate change - how can such a model possibly encapsulate the uncertainties of the physical world. And how can "skeptics" possibly put any faith in an economic model when they dismiss climate models so thoroughly? Yet they do!

I should have added links to Retraction Watch and to Andrew Gelman:

http://retractionwatch.com/2015/07/22/second-correction-for-controversial-paper-on-economic-gains-of-climate-change/

http://andrewgelman.com/2014/05/27/whole-fleet-gremlins-looking-carefully-richard-tols-twice-corrected-paper-economic-effects-climate-change/

"Of course, all of these studies are of academic interest only. It seems laughable to expect an economic model to be able to predict the outcome of climate change - how can such a model possibly encapsulate the uncertainties of the physical world. And how can "skeptics" possibly put any faith in an economic model when they dismiss climate models so thoroughly? Yet they do!

Nov 24, 2015 at 5:19 PM | Unregistered CommenterRaff"<.blockquote cite="">

FWIW, I don't put much trust in the models of the 'dismal science' either. But most alarmists don't even make a token effort to pretend that they are considering likely benefits. They simply don't want there to be any benefits, else they might be out of a job.

May as well post it again, with the proper block quotes. In any case, I need to get another 403 error to post it for squarespace to do nothing about it still.

"Of course, all of these studies are of academic interest only. It seems laughable to expect an economic model to be able to predict the outcome of climate change - how can such a model possibly encapsulate the uncertainties of the physical world. And how can "skeptics" possibly put any faith in an economic model when they dismiss climate models so thoroughly? Yet they do!

Nov 24, 2015 at 5:19 PM | Unregistered CommenterRaff"

FWIW, I don't put much trust in the models of the 'dismal science' either. But most alarmists don't even make a token effort to pretend that they are considering likely benefits. They simply don't want there to be any benefits, else they might be out of a job.

The question is how can anybody use any of these studies to argue that climate change will be beneficial? It is incredible both from the perspective of what the studies purport to show and from the very concept of believing what an economic model shows. So why does Ridley keep doing it?

Let's put it a third way, how can anyone argue with raff when his modus operandi when being beaten is to vanish and start another thread?

TBYJ, as Mike Jackson pointed out on another thread, Raff also went and started another thread on the same subject. It's either Alzheimer's or wilful trolling. Given Raff's history, I know which one I would choose as being the more likely. Perhaps he/she thinks it is somehow going to make a difference in Paris.

michael hart,

Raf has already indicated he thinks the Bish is more influential than Obama, Greenpeace, Emma Thompson and the BBC. Who knows what he can achieve?

Who needs studies when history shows that cooler than present causes problems, Late Bronze Age Cooling, Post Roman Cooling and LIA warmer than now is good and humans flourish, Minoan Climate Optimum, Roman warm period and Medieval Warm Period? As, despite recent warming, we're currently in a particularly cool period warming should be welcomed whatever the cause.

"being beaten"? Hardly. I asked why the Bishop would print graphs he knew were false and the only real answers were from Tiny, who says any lying for the cause is alright by him if it works, and from Ratty, who says that the Bishop was just settling a tiff between his GWPF friends about that graph. The latter is a nice try, but it is typically false. Neither the Viscount nor the Tol mentioned Tol 2009 (in what was quoted) so the Bishop had a free choice of what to use to settle the bun-fight. He could have shown that Ridley is simply wrong using a recent paper like Tol 2104, which shows no benefit from zero warming upwards, but instead he used the invalid 2009 paper that Tol 2014 replaced. So the question of why the Bishop would print a graph he knew was false remains. The only logical answer is the excuse I offered - that he didn't know of Tol 2014 despite knowing well that Bob Ward had found errors in it and despite the fact that I had mentioned it (so maybe he doesn't read my comments...). This excuse is not credible for someone who follows the climate scene so closely, but all the same he has even less excuse for not knowing about Tol 2014 now that his discussion forum has hosted two discussions of it.

It is interesting that Ridley's statement that "the world would probably benefit from a temperature rise of up to 2C" might be expected to have people like MartinA climbing up the wall shouting "liar!". 2C from when? His statement implies from now and Tol 2009 and 2014 both show that a 2C rise from now leading to a "welfare impact" of minus 2-3%. Or he could mean 2C rise since pre-industrial, which the graphs use as a reference. But in this case, for both Tol 2009 and 2014 the "welfare impact" is about minus 1-2% (in the case of Tol 2009 this is loss of the gain already in the bag since pre-industrial times). Any way you look at it, Ridley is claim is unsupported. The Bishop's choice of graph to defend Ridley just makes him look partisan and either ignorant (of Tol 2014) or stupid (for not understanding the graphs). Take your choice.

tl;dr

To anyone who understands language and logic, Ridley's statement is wrong. Whichever way you read his 2C rise (from now or from pre-industrial) the effect from now-on is negative according to any of Tol's many graphs. I imagine he will keep on saying it and you will all love him for it.

Ratty, if Ridley is going to use a graph to show net benefit from 2C warming he needs to choose one where the curve goes up (assuming benefit is plotted increasing upwards). Tol's graphs in his 2009 and 2015 papers are at their peak at current temperatures; the graphs go down from now-on. Remember the graphs need to go up for net benefit. The graph in Tol 2014 goes down all the way. Up and down - that should be simple enough for a Viscount and even for you to understand.

You might, if you understood it, argue that Ridley meant there would be net benefit from 2C of warming relative to pre-industrial times. But I've not heard him say that, only that there will be net benefit up to 2C, which to most people means benefit relative to now. And what is important is that all of the graphs show it is downhill from now.

Raff, you can now either 1: answer the question "can you name any negative effects that can categorically (and verifiably) be attributed to global warming"?

or 2: crawl back under your stone.

( I suppose that you could 3: start another discussion to ask what ice cream flavour people prefer. )

Jolly Farmer, can you identify any one (or million) lung cancer patient who is "categorically (and verifiably)" dying because of smoking?

"Categorically and verifiably" is the last resort of scoundrels (just ahead of patriotism, apparently).

Ratty asked "why?" to the statement, "And what is important is that all of the graphs show it is downhill from now." Answer, because that is what the graphs show and if you, Ridley or the Bishop want to use those graphs to support your arguments you have to explain why they all head down. The only alternative is that you are reading the graphs upside down - given your level of understanding that is of course possible.

The graphs might be wrong of course. I put no faith in them. There might be gains from climate change. There are obvious lower heating costs, yet only one of the 21 studies in Tol's papers find much overall gain. The Viscount likes to pretend that the evidence supports his claims despite the evidence being against him. Let him claim net positive change, just without asking people to stand on their heads when looking at the evidence.

Ratty, how can you disentangle any supposed gains from warming from the huge economic changes that have occurred in the last century. You just can't justify the claim of a net gain from warming to the degree of certainty that you demand from me. Even lower heating costs, which might look like a clear gain, mean lower profits for energy providers - net gain is zero.

Ridley has in the past misinterpreted Tol's work to claim net benefit up to 3C warming from pre-industrial. And he has used the same work to say, "The literature is very clear; 2C is when we start to get harm." despite the work having been discredited. The guy is a joke, but I guess you followers of the Tiny doctrine - any lie for the cause is good if it works - are happy with support from clowns. You have enough of them.