What would constitute AGW being a major problem?

Ron Clutz has an excellent post. This time on he reports on A Critical Framework for Climate Change. In the post Ron looks at the Karoly/Tamblyn–Happer Dialogue on Global Warming at Best Schools particularly at Happer’s major statement. In my opinion these dialogues are extremely useful, as (to use an old-fashioned British term) are antagonists are forces by skilled opponents to look at the issues in terms of a level playing field. With the back and forth of the dialogue, the relative strengths and weaknesses are exposed. This enables those on the outside to compare and contrast for themselves. Further, as such dialogues never fully resolve anything completely, can point to new paths to develop understanding. 

Ron reprints two flow charts. Whilst the idea is of showing the issues in this way to highlight the issues is extremely useful correct. I have issues with the detail. 


In particular on the scientific question “Is it a major problem?“, I do not think the “No” answers are correct.
If there was no MWP, Roman warming, or Bronze Age warming then this would be circumstantial evidence for current warming being human-caused. If there has been 3 past warming phases at about  1000, 2000 and 3000 years ago, then this is strong circumstantial evidence that current warming is at least in part due to some unknown natural or random factors. Without any past warming phases at all then it would point to the distinctive uniqueness of the current warming, but that still does not mean not necessarily mean that it is a major net problem. There could be benefits as well as adverse consequences to warming. But the existence of previous warming phases under many studies and only being able to claim by flawed statistics that the majority of warming since 1950 in human-caused (when there was some net warming for at least 100 years before that suggests a demonstrable marginal impact of human causes far less than 100% of total warming. Further there is issues with

(a) the quantity of emissions a trace gas to raise that the atmospheric levels by a unit amount

(b) the amount of warming from a doubling of the trace gas – climate sensitivity

(c) the time taken for rises on a trace gas to raise temperatures.

As these are all extremely difficult to measure, so a huge range of equally valid answers. It is an example of the underdetermination of scientific theory.

At the heart of the underdetermination of scientific theory by evidence is the simple idea that the evidence available to us at a given time may be insufficient to determine what beliefs we should hold in response to it.

But even if significant human-caused warming can be established, this does not constitute a major problem. Take sea-level rise. If it could be established that human-caused warming was leading to sea level rise, this may not, on a human scale, be a major problem. At current rates sea levels from the satellites are rising on average by 3.5mm per year. The average adjusted level from the tide gauges are less than that – and the individual tide gauges show little or no acceleration in the last century. But if that rate accelerated to three or four times that level, it is not catastrophic in terms of human planning timescales. 

The real costs to humans are expressed in values. The really large costs of climate change are based not so much on the physical side, but implausible assumptions about the lack of human responses to ongoing changes to the environment. In economics, the neoclassical assumptions of utility maximisation and profit maximisation are replaced by the dumb actor assumption.

An extreme example I found last year. In Britain it was projected that unmitigated global warming could lead to 7000 excess heatwave deaths in the 2050s compared to today. The projection was most of these deaths would occur in over 75s dying in hospitals and care homes. The assumption was that medical professionals and care workers would carry on treating those in the care in the same way as currently, oblivious to increasing suffering and death rates.  

Another extreme example from last year was an article in Nature Plants (a biology journal) Decreases in global beer supply due to extreme drought and heatThere were at least two examples of the dumb actor assumption. First was failure by farmers to adjust output according to changing yields and hence profits. For instance in Southern Canada (Calgary / Edmonton) barley yields under the most extreme warming scenario were projected to fall by around 10-20% by the end of the century. But in parts of Montana and North Dakota – just a few hundred miles south – they would almost double. It was assumed that farmers would continue producing at the same rates regardless, with Canadian farmers making losses and those in Northern USA making massive windfall profits. The second was in retail. For instance the price of a 500ml bottle of beer in Ireland was projected to increase under the most extreme scenario in Ireland by $4.84 compared to $1.90 in neighbouring Britain. Given that most of the beer sold comes from the same breweries; current retail prices in UK and Ireland are comparable (In Ireland higher taxes mean prices up to 15% higher); cost of a 500ml bottle is about $2.00-$2.50 in the UK; and lack of significant trade barriers, there is plenty of scope with even a $1.00 differential for an entrepreneur to purchase a lorry load of beer in the UK and ship it over the Irish Sea. 

On the other hand nearly of the short-term forecasts of an emerging major problem have turned out to be false, or highly extreme. Examples are

  • Himalayan Glaciers will disappear by 2035
  • Up to 50% reductions in crop yields in some African Countries by 2020
  • Arctic essentially ice-free in the summer of 2013
  • Children in the UK not knowing what snow is a few years after 2000
  • In the UK after 2009, global warming will result in milder and wetter summers

Another example of the distinction between a mere difference and a major problem is the February weather. Last week the UK experienced some record high daytime maximum temperatures of 15-20C. It was not a problem. In fact, accompanied by very little wind and clear skies it was extremely pleasant for most people. Typical weather for the month is light rain, clouds and occasional gales. Children on half-term holidays were able to play outside, and when back in school last week many lessons were diverted to the outdoors. Over in Los Angeles, average highs were 61F (16C) compared to  February average of 68F (20C). This has created issues for the elderly staying warm, but created better skiing conditions in the mountains. More different than a major problem. 

So in summary, for AGW to be a major problem it is far from sufficient to establish that most of the global warming is human caused. It is necessary to establish that the impact of that warming is net harmful on a global scale.

Kevin Marshall


Bjorn Lomborg on Climate Costs in the Australian

Australian Climate Madness blog points to an article, “Wrong way, go back“, in the Australian Newspaper by Skeptical Environmentalist Bjorn Lomberg on Australia’s climate policies. This is my comment.

This statement in the article is significant

When economists estimate the net damage from global warming as a percentage of gross domestic product, they find it will indeed have an overall negative impact in the long run but the impact of moderate warming (1C-2C) will be beneficial. It is only towards the end of the century, when temperatures have risen much more, that global warming will turn negative.

Now consider the Apocalypse Delayed? posting of March 28th. Referring to an Economist article, it says that a number of empirical studies show that climate sensitivity is much lower than the climate models assume. Therefore, moving into the net cost range seems much less likely.
But why are there net costs? Lomberg’s calculations are based on William Nordhaus’s DICE model that

calculates the total costs (from heat waves, hurricanes, crop failure and so on) as well as the total benefits (from cold waves and CO2 fertilisation).

I would claim that the destablisation of the planet’s climate by rapid warming has very little evidence. Claims in AR4 that hurricanes were getting worse; that some African countries would see up to a 50% reduction in crop yields by 2020; that the Himalayan Glaciers would largely disappear by 2035; that the Amazon rainforest could catastrophically collapse – all have been over-turned.
Thus the policy justification for avoiding climate catastrophe as a result rising greenhouse gases is a combination of three components. First, a large rise in temperatures. Second, the resulting destablisation of the climate system having net adverse consequences. Third, is that the cost of constraining the rise in greenhouse gases is less than the cost of doing nothing.
It is only this third aspect that Bjorn Lomberg deals with. Yet despite that he shows that the Australian Government is not “saving the planet for future generations”, but causing huge net harm. Policy-making should consider all three components.

That is, there are three components to the policy justification to combatting “climate change” by constraining the growth in greenhouse gas emissions

  1. That there will be a significant amount of global warming.
  2. That this is net harmful to the planet and the people on it.
  3. That the net harm of policies is less than the net harm of warming. To use a medical analogy, the pain and risks of treatment are less than the disease.

Lomberg, using the best cost model available, comes up with far less costs of global warming than, say, the Stern Review of 2006. He also uses actual policy costs to assess the net harm of global warming. Lomberg does not, however, challenge the amount of warming from a given quantity of CO2 rise, nor the adverse consequences of that warming. The Economist article
and editorial of March 30th conversely challenges the quantity of warming from arising from a given rise in CO2, but just sees it as “apocalypse delayed” and not “apocalypse debunked“.

Kevin Marshall

IPCC’s 1990 Temperature Projections – David Evans against Mike Buckley

The following comments by Mike Buckley (referenced here) are more revealing about the state of climate science than any errors on Evan’s part.

  1. Surface Temperatures v lower tropospheric temperatures.

    As a beancounter (accountant) I like to reconcile figures. That is to account for the discrepancies. Jo Nova, Anthony Watts and others have found numerous reasons for the discrepancies. The surface temperature records have many “adjustments” that brings reality into line with the models. Whatever excuses you can conjure up, as an accountant I would say that they fail to offer a “true and fair view”.

  2. Trend lines should not start at the origin.

    So you disagree with standard forecasting? That is you start with the current position.

  3. Trend lines should be curved.

    Agreed. This is for simplicity. See next point.

  4. Trend lines should be further apart.

    Are you saying that the climate models have a wider predictive band of 0.75 celsius over 25 years? If they were straight lines, over a century they cannot get within 3 degrees. If Dr Evans had not simplified, the range would have been much greater.

There is a way of more precisely comparing the models with the actuals. The critical variable is CO2 levels. Therefore we should re-run the models from 1990 with actual CO2 data. By then explaining the variances, we can better achieve better understanding and adjust the models for the future. But there is plenty of evidence that this needs to be done by people who are independent. It will not happen, as the actual rise in CO2 was similar to the highest projections of the time.

The philosopher of science Karl Popper is remembered for the falsification principle. A less stringent criteria is that progressive science confronts the anomalies and gets predictions ever closer to the data. Pseudo-science closes ranks, makes up excuses, and “adjusts” perceptions of reality to fit the theory. Progressive science is highly competitive and open, whilst pseudo-science becomes ever more dogmatic, intolerant and insular.

Climate Change Damage Impacts – A story embellished at every retelling

Willis Eschenbach has a posting on a recent paper on climate change damage impacts. This is my comment, with hyperlinks and tables.

My first reaction was “Oi– they have copied my idea!”

Well the damage function at least!


Actually, this can be found by the claims of the Stern Review or AR4. Try looking at the table in AR4 of “Examples of impacts associated with global average temperature change” and you will get the idea.

A simpler, but more visual, perspective is gained from a slide produced for the launch of the Stern Review.

More seriously Willis, this is worse than you thought. The paper makes the claim that unlikely but high impact events should be considered. The argument is that the likelihood and impacts of potential catastrophes are both higher than previous thought. The paper then states

“Various tipping points can be envisaged (Lenton et al., 2008; Kriegler et al., 2009), which would lead to severe sudden damages. Furthermore, the consequent political or community responses could be even more serious.”

Both of these papers are available online at PNAS. The Lenton paper consisted of a group of academics specialising in catastrophic tipping points getting together for a retreat in Berlin. They concluded that these tipping points needed to include “political time horizons”, “ethical time horizons”, and where a “A significant number of people care about the fate of (a)

component”. That is, there is a host of non-scientific reasons for exaggerating the extent and the likelihood of potential events.

The Krieger paper says “We have elicited subjective probability intervals for the occurrence of such major changes under global warming from 43 scientists.” Is anybody willing to assess if the subjective probability intervals might deviate from objective probability intervals, and in which direction.

So the “Climate Change damage impacts” paper takes two embellished tipping points papers and adds “…the consequent political or community responses could be even more serious.”

There is something else you need to add into the probability equation. The paper assumes the central estimate of temperature rise from a doubling of CO2 levels is 2.8 degrees centigrade. This is only as a result of strong positive feedbacks. Many will have seen the recent discussions at Climateaudit and wattsupwiththat about the Spencer & Bracewell, Lindzen and Choi and Dessler papers. Even if Dessler is given the benefit of the doubt on this, the evidence for strong positive feedbacks is very weak indeed.

In conclusion, the most charitable view is that this paper takes an exaggerated view (both magnitude and likelihood) of a couple of papers with exaggerated views (both magnitude and likelihood), all subject to the occurrence of a temperature rise for which there is no robust empirical evidence.

Al Gore’s faulty case for CAGW

Wattsupwiththat have an estimate of Al Gore’s Climate Reality online viewing figures. I posted at the follow-up article

manicbeancounter says:

September 22, 2011 at 12:17 pm

I was one of those who stayed for over 5 minutes.

A video they had justified the case for global warming by re-doing the CO2 in a jar experiment – very nicely as well. Only they did not say what the concentrations were compared to the atmosphere (probably >1000 times the 0.04% at the moment).

Then in the space of a sentence mentioned feedbacks amplifying the effect.

So of the predicted warming up to 6 degrees centigrade this century predicted by the most extreme alarmists, Al Gore’s little video had a flawed experiment to justify the insignificant first 20%, and a “trust the computer models” for the alarming bit.

Don’t take my word for it – I am just a (slightly) manic beancounter. Check out for yourself at http://climaterealityproject.org/video/climate-101/

By the way – don’t worry about the stats – Alexa currently ranks this site at 16,989 and Climate Reality at 64,734.

REPLY: I have a post coming up on this video, which is online here also, without the need to visit Gore’s site: http://vimeo.com/28991442

Feedbacks in Climate Science and Keynesian Economics

Warren Meyer posts of a parallel between Climate Science and Keynesian Economics. I posted about a subject close to his heart, and central to Keynesianism – Feedbacks. I have also attempted to update on the current debate on feedbacks.


There is a parallel between Keynes and the CAGW that is close to your heart – feedbacks. Pure Keynesianism is that an increase in government expenditure at less than full employment would have a positive feedback response. Keynes called the feedback measure the multiplier. (The multiplier is the reciprocal of the proportion of Government expenditure to GDP. So if government expenditure was 20% of GDP, then a $1bn fiscal boost would increase output by $5bn.)

By the 1950’s the leading sceptic was Milton Friedman who, in his 1962 book “Capitalism and Freedom”, estimated empirically that the multiplier was about 1 – that is it did not have any impact. Friedman was denounced as a denier and a dinosaur. (At the same time, mainstream economics adapted his verificationist methodology.) Indeed by the end of the 1960s it was generally agreed that the long-term feedback impact of government demand management was negative, as increased government expenditure crowded out the private sector, caused escalating inflation (as economic actors ceased to be fooled by the false signals 0f increased expenditure), slowed economic growth and generally undermined the very structures of the capitalist system. (see Friedman’s Nobel Prize lecture “Inflation and Unemployment“)

Keynesian thinking is that the capitalist economic system is inherently unstable. Stability is only achieved through the guiding hand of government. Keynes contrasted this with a caricature of neoclassical economics, with the macroeconomic system would rapidly come back into equilibrium. Similarly, the climate models assumption of chronic instability is contrasted by an extreme caricature of those who disagree with them. That is the “deniers” are saying that the climate is incredibly stable, with human beings having no influence. In both cases the consequence of this caricaturing is to automatically claim any extreme occurrence as vindification of their perspective.