Time will run out to prevent 2°C warming barrier being breached

I have a number of times referred to a graphic “Figure 2 Summary of Results” produced by the UNFCCC for the Paris COP21 Climate Conference in December 2015. It was a centerpiece of the UNFCCC Synthesis report on the aggregate effect of INDCs.

The updated graphic (listed as Figure 2, below the Main Document pdf) is below

This shows in yellow the impact of the INDC submissions covering the period 2015 to 2030) if fully implemented against limiting warming to 2°C  and 1.5°C . This showed the gulf between the vague policy reality and the targets. Simply put, the net result of the INDCs submissions would insufficient for global emissions to peal Yet in reaching an “agreement” the representatives of the entire world collectively put off recognizing that gulf.

For the launch of the UNIPCC AR5 synthesis report in 2014, there were produced a set of slides to briefly illustrate the policy problem. This is slide 20 of 35, showing the  reduction pathways.


The 2°C  of warming central estimate is based upon total GHG emissions in the 21st Century being around 2500 GtCO2e.

At the launch of 2006 Stern Review Sir Nicholas Stern did a short Powerpoint presentation. Slide 4 of the PDF file is below.


The 450ppm CO2e emissions pathway is commensurate with 2°C  of warming. This is based upon total GHG emissions in the 21st Century being around 2000 GtCO2e, with the other 500 GtCO2e presumably coming in the 22nd Century.

The UNFCCC Paris graphic is also based on 2500 GtCO2e it is also possible to calculate the emissions reduction pathway if we assume (a) All INDC commitments are met (b) Forecasts are correct (c) no additional mitigation policies are enacted.

I have produced a basic graph showing the three different scenarios.

The Stern Review assumed global mitigation policy would be enacted around 2010. Cumulative 21st Century emissions would then have been around 450 GtCO2e. With 500 GtCO2e allowed for post 2100, this gave average emissions of around 17 GtCO2e per annum for the rest of the century. 17 GtCO2e, is just under 40% of the emissions in the year the policy would be enacted.

IPCC AR5  assumed global mitigation policy would be enacted around 2020. Cumulative 21st Century emissions would then have been around 950 GtCO2e. A presentation to launch the Synthesis Report rounded this to 1000 GtCO2e as shown in slide 33 of 35.

Assuming that global emissions were brought to zero by the end of the century, this gave average emissions of 20 GtCO2e per annum for the rest of the century. 20 GtCO2e, is just under 40% of the emissions in the year the theoretical global policy would be enacted. The stronger assumption of global emissions being reduced to zero before the end of the century, along with a bit of rounding, offsets the delay.

If the Paris Agreement had been fully implemented, then by 2030 cumulative 21st Century emissions would have around 1500 GtCO2e, leaving average emissions of around 14 GtCO2e per annum for the rest of the century. 17 GtCO2e, is just over 25% of the emissions in the year the policy would be enacted. The failure of the Paris Agreement makes it necessary for true global mitigation policies, if in place by 2030, to be far more drastic that those of just a few years before to achieve the same target.

But the Paris Agreement will not be fully implemented. As Manhatten Contrarian (hattip The GWPF) states, the US was the only major country proposing to reduce its emissions. It looks like China, India, Indonesia, Russia and Germany will all increase their emissions. Further, there is no indication that most countries have any intention of drastically reduce their emissions. To pretend otherwise is to ignore a truism, what I will term the First Law of Climate Mitigation

To reduce global greenhouse gas emissions, the aggregate reduction in countries that reduce their emissions must be greater than aggregate increase in emissions in all other countries.

Modeled projections and targets are rendered meaningless if this truism is ignored. Yet this is what the proposers of climate mitigation policy have been effectively doing for many years. Emissions will therefore breach the mythical 2°C warming barrier, but based on recent data I believe warming will be nowhere near that level.

Kevin Marshall



£319 billion on Climate Change for approximately nothing

The major reason for abandoning the Climate Change Act 2008 is not due to the massive financial burden imposed on families, but because it will do approximately nothing to curb global greenhouse gas emissions. Massive costs are being imposed for near zero prospective benefit.

At the weekend the GWPF published a paper by Peter Lilley MP on the costs of The Climate Change Act 2008. From 2014 to 2030 he estimates a total cost of £319 billion to ensure that in 2030 British greenhouse gas emissions are 57% below their 1990 levels.
Putting this into context, listen to then Environment Minister David Miliband introducing the Climate Change Bill in 2007.

The 2008 Act increased the 2050 target from 60% to 80%. Miliband recognizes that what the UK does is not sufficient to stop a global problem. That requires a global solution. Rather, the aim is for Britain to lead the way, with other industrialized countries encouraged to follow. The developing countries are given a free choice of “a low carbon path of development rather than to repeat the mistakes of the industrialized countries.

Over eight years after the little video was made and seven years after the Climate Change Act was passed (with an increased 2050 emissions reduction target of 80% reduction on 1990 levels) was the COP21 in Paris. The responses from other countries to Britain’s lead were in the INDC submission, which the UNFCCC summarized in a graph, and I have annotated.

The UNFCCC have four bands. First, in orange, is the Pre-INDC scenarios. Then in yellow is the projected global impact if all the vague policy proposals are full enacted. In blue is the least cost 2◦C pathway for global emissions reductions, whilst in green is the least cost 1.5◦C pathway.

I have superimposed lilac arrows showing the UK Climate Act proportionate emissions pathway achieving a 57% emissions reduction by 2030 and an 80% emissions reduction by 2050 compared to the baseline 1990 emissions. That is, if all countries were to follow Britain’s lead, then the 2◦C warming limit would not be breached.

What this clearly shows is that collectively countries have not followed Britain’s lead. Even if the policy proposals were fully enacted (an unlikely scenario) the yellow arrow quite clearly shows that global emissions will still be rising in 2030.

This needs to be put into context of costs and benefits. The year before David Miliband launched the Climate Bill the Stern Review was published. The Summary of Conclusions gave the justification for reducing greenhouse emissions.

Using the results from formal economic models, the Review estimates that if we don’t act, the overall costs and risks of climate change will be equivalent to losing at least 5% of global GDP each year, now and forever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20% of GDP or more. In contrast, the costs of action – reducing greenhouse gas emissions to avoid the worst impacts of climate change – can be limited to around 1% of global GDP each year.

Britain is spending the money to avert catastrophic global warming, but future generations will still be subjected to costs of climate catastrophe. It not much worse in terms of wasting money if the Stern Review grossly exaggerated the likely costs of warming and massively understated the policy costs, as Peter Lilley and Richard Tol laid out in their recent paper “The Stern Review : Ten Years On“.

However, if the British Government had conducted some proper assessment of the effectiveness of policy (or the Opposition has done their job in holding the Government to account) then it would have been clear that sufficient countries would never follow Britain’s lead. Last year Robin Guenier published some notes on Supreme Court Justice Phillip Sands lecture CLIMATE CHANGE and THE RULE OF LAW. Guenier stated of the Rio Declaration of 1992

There’s little, if any, evidence that the undoubted disagreements about the science – the focus of Professor Sands’ concern in his lecture – are the reason it’s proving so difficult to come to an effective agreement to restrict GHG emissions. In contrast however, the Annex I / non-Annex I distinction has had huge consequences. These arise in particular from Article 4.7:

“The extent to which developing country Parties will effectively implement their commitments under the Convention … will take fully into account that economic and social development and poverty eradication are the first and overriding priorities of the developing country Parties.” [My emphasis]

When the Convention was enacted (1992) the effective exemption of developing countries from environmental constraint made some sense. But over the years Non-Annex I countries, which include major economies such as China, India, South Korea, Brazil, South Africa, Saudi Arabia and Iran, have become increasingly powerful: in 2012 responsible for 67% of global CO2 emissions.

Robin Guenier uses estimates for CO2 emissions not (the admittedly harder to estimate) GHG emissions, of which CO2 comprises about two-thirds. But estimates are available from from the European Commission’s “Emissions Database for Global and Atmospheric Research” (EDGAR) for the period 1990 to 2012. I divided up the emissions between the Annex countries and the Non-Annex countries. 

The developing countries accounted for 64% of global GHG emissions in 2012, up from 47% in 1990 and 57% in 2005 when the Stern Review was being written. From 1990 to 2012 global emissions increased by 41% or 15,700 MtCO2e, whilst those of the Non-Annex countries increased by 90% or 16,400 MtCO2e  to 34,600 MtCO2e. The emissions in the United Kingdom decreased in the period (mostly for reasons other than mitigation policies) by 25% to 586 MtCO2e or 1.1% of the estimated global total.

It would have been abundantly clear to anyone who actually looked at the GHG emissions figures by country that the Rio Declaration 1992 was going to prevent any attempt to significantly reduce global GHG emissions. Since 1992 the phenomenal economic growth of countries like China and India, driven by the low energy costs of fossil fuels, have made the impossibility of reducing global emissions even starker. Yet still the IPCC, UNFCCC, many Governments and a large Academic consensus have failed to acknowledge, let alone understand, the real world data. Still they talk about reducing global emissions by over 80% in a couple of generations. In terms of the United Kingdom, the INDC submissions produced last year should have been further confirmation that the Government has no rational justification for imposing the massive costs on families, increasing inequalities and destroying jobs in the process.

Kevin Marshall


Update on a Global Carbon Tax

In a previous post I looked a statement made by Richard Tol in his recent paper The Structure of the Climate Debate

Only a modest carbon tax is needed to keep atmospheric concentrations below a high target but the required tax rapidly increases with the stringency of the target. If concentrations are to be kept below 450 ppm CO2eq, the global carbon tax should reach some $210/tCO2 in 2020 or so (Tol 2013).

Tol, to his credit, replied to me (and others) in the cliscep comments. In particular

Note that these climate policies consist of two components: An initial carbon tax, and its rate of increase (4-6% a year).

The $210 carbon tax in 2020 is just a starting point. With a 5% escalation, it would double every 14 years making the carbon tax $910 in 2050, $3070 in 2075 and $10,400 in 2100. The escalator is the far more important aspect in reducing demand for fossil fuels through a combination of reducing energy use and switching to more expensive (and often less convenient) renewable sources. The escalator was not clear in the original article, and Richard Tol has agreed to make a correction.

Consider again just imposing a fixed $210 carbon tax. From the British perspective the additional tax on petrol (gasoline), with 20% VAT applied, is equivalent to 47p a litre added to the retail price. The tax is already nearly 70p a litre, so unlikely to have the impact on motorists of reducing their consumption by 90% or more. Even with the tax at 200p a litre implied by a $910 t/CO2 tax (making petrol £3.13 a litre) may not achieve this objective. For a car doing 15000 miles at 39mpg, this would generate an additional cost to the owner of £3500 per year. It would still be less than the depreciation on a family car averaged over the first three years. It might also be less than the full costs of converting to electric cars, particularly if the roll-out was not subsidized on the purchase cost and provision of charging points. Within the UK, the carbon tax would also replace the current renewables policy. Here the escalator would really hit home. For coal-fired power stations producing 400kg CO2 per megawatt hour, the carbon tax would be £70Mwh in 2020 and £300Mwh in 2050. Gas-fired power stations would have a tax of about half that level. Even wind turbines, backed by massive pump-storage schemes would be much cheaper. Nuclear power would be the cheapest alternative of all. But British voters are hardly going to keep on voting for a Government that imposes real increases in taxes of five percent a year until they become unaffordable except for the very rich.

However, it is from the global perspective that the cost of the carbon tax really hits home. In another comment Tol says

The big worry for climate policy, studiously avoided by the majority of its advocates, is that you need lots of cheap energy in the early stages of economic development.

It is worth stating again that a Global Carbon Tax needs to be Global to achieve the desired objectives. From the UNIPCC AR5 Synthesis Report Summary for Policy Makers is graphic SPM11(a). This shows the non-policy or Business as Usual RCP8.5 scenario, where emissions in 2100 are projected to be over 2.5 times the level of 2010. The 2C warming target is the RCP2.6 scenario. I have inserted a big arrow to show the difference that the global carbon tax needs to make. It can be demonstrated that most of the emissions growth will come from the developing countries, following the pattern from at least 1990.

The scale of the harm of policy is by assuming that the $210 carbon tax is applied without any change in demand at all, using the estimated CO2 emissions from fossil fuels for 2013 from CDIAC and the IMF 2015 GDP figures for ballpark estimates.
Global CO2 emissions from fossil fuels were about 33.8 billion tonnes (two-thirds of total GHG emissions). A $210 carbon tax without any effect on demand would thus generate $7100 bn. This represents nearly 10% of global GBP of $73500bn. If we assume 2% emissions growth and 3% economic growth, then the carbon tax would represent 9.6% of GDP in 2020 without any drop in emissions.
Here is the same calculation for selected countries using 2013 emissions and GDP data.

30-33% Iran, Russia, South Africa
19-20% India, China
16-18% Thailand, Malaysia, Vietnam
11-14% Poland, Czech Republic, Pakistan, Egypt, Indonesia.
7% Bangladesh, Philippines
6-7% USA, Japan, Canada, Australia
4-5% Spain. Germany, Nigeria
UK 3.4% France 2.9%

The highest tax rates are a result of inefficient economic systems. Iran has subsidised petrol, effectively a negative carbon tax. South Africa’s high emissions are as a result of apartheid. Oil embargoes caused it to convert coal to liquids, a process that generates 4-5 times the CO2 of burning coal alone. Russia, in common with its neighbours, still has the legacy of the economically-inefficient communism.
The carbon tax would also be high as a proportion of GDP for the rapidly emerging economies. It highlights the Tol’s comment about needing lots of cheap energy in the early stages of economic development. With higher fossil fuel emissions per $1000 of GDP the impact on output would be relatively greater in the emerging economies than in the OECD. A globally uniform carbon tax would end up transferring back some manufacturing back to the more energy efficient economies, slowing economic growth and thus emissions growth.
More importantly, emerging countries have large parts of the population with very low energy consumption. Even those with access to gas and electricity have much lower energy consumption than is typical in the West, whether from heating, air conditioning, cooking, or private transport. Pushing up the cost of energy will massively slow down the spread of consumerism and consequent improvements in living standards.

Three years ago I looked at the takeaway policy quote from the Stern Review.

Using the results from formal economic models, the Review estimates that if we don’t act, the overall costs and risks of climate change will be equivalent to losing at least 5% of global GDP each year, now and forever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20% of GDP or more. In contrast, the costs of action – reducing greenhouse gas emissions to avoid the worst impacts of climate change – can be limited to around 1% of global GDP each year.

I largely agree with Richard Tol when he states that a carbon tax is the optimal policy in terms of maximum effect for minimum cost, at least with respect to fossil fuel emissions. Yet a high, and rapidly increasing, carbon tax would cost far more than 1% of global GDP each year, even if the additional tax revenue was spent efficiently and/or used to reduce other taxes. But the most pernicious effects would be felt in the effects on long-term economic growth – the very growth that is moving billions of people out of poverty towards the far better living standards we enjoy in the Western World. The  carbon tax does not present a feasible policy even in theory to achieve the objectives desired. Yet is, in theory, the best policy available.

Kevin Marshall

Plans to Increase Global Emissions at COP21 Paris


It is a necessary, but far from sufficient, condition to cut global greenhouse gas emissions for any increases in emissions in some parts of the world to be offset by emissions cuts elsewhere. INDC submissions for the COP21 in Paris contain proposed emissions targets between 2010 and 2030 suggest the opposite will be case. For every tonne of emissions reductions in 32 leading developed countries there will be at least three tonnes of emissions increases in 7 major developing countries. The net effect of these targets being achieved from these countries (which combined make up both 60% of global emissions and 60% of global population) will be to make global emissions 20% higher in 2030 than 2010. Using UNIPCC AR5 projections, unless there are large and rapid cuts in in global greenhouse emissions post 2030, any agreement based those submissions will not save the world from two degrees of dangerous global warming and will likely not save the world from three degrees of warming. This leads to a policy problem. Emissions reduction policies will only reduce a small part of the harms of climate change. So even if the more extreme claims of climate catastrophism are true, then it might be more beneficial for a nation to avoid emissions reduction policies.


In the following analysis makes these assumptions.

  • UNIPCC estimates of the relationship between global average temperature and atmospheric greenhouse gas levels are accurate.
  • UNIPCC estimates of the relationship between greenhouse gas emissions and atmospheric greenhouse gas levels are accurate.
  • Policy commitments will always turn into concrete policy.
  • Climate change policy priorities will not conflict with other priorities.
  • All policy will be effectively implemented in full, implying the requisite technological and project management capacities are available.

The Context

The World’s leaders meeting from 30 November to December 11 in Paris together to thrash out a plan to save the world from a dangerous two degrees of warming. In preparation 146 countries, representing 87% of Global Emissions have submitted plans to the United Nations Framework Convention on Climate Change (UNFCCC). These are available at the submissions website here. There is no-one who has gone through to evaluate whether these submissions are consistent with this objective. I have chosen a small sample of 7 major developing nations and 32 developing nations (EU 28 have a single target) which combined represent about 60% of global emissions and 60% of global population.

The level of global emissions control required to constrain global warming is given by the IPCC in their final version of the 2014 AR5 Synthesis Report page 21 Figure SPM 11(a) and reproduced below.

The dark blue band is the maximum emissions pathway to avoid going beyond 2 degrees of warming, with RCP2.6 denoting the central pathway. The dark orange pathway would produce 2.5-3.0 degrees of warming. According to the figure SPM 5(a) Annual GHG emissions in 2010 were 49 GtCO2. They are currently increasing by at least 2% a year. The extrapolated projection for 2030 is 70-75 GtCO2, roughly following the solid black line of the RCP8.5 BAU (non-policy) scenario. In 2015 this will be about 54 GtCO2. The minimum for policy is that global emissions should be at least no higher than they were in 2010, and preferably below that level to offset the cumulative overshoot that will occur.

How does the global policy requirement fit in with the country submissions?

If the IPCC projections are correct, to avoid 2 degrees of warming being exceeded there needs to be a global cap on greenhouse gas emissions of around 50 GtCO2 almost immediately and for that level to start to start falling in the early 2020s. Alternatively, if global emissions reach 60 GtCO2 without any prospect of major reductions thereafter then from the model projections three degrees of warming is likely to be exceeded. There is a large gap between these two scenarios, but even with submissions from a limited number of the major countries it is possible to state that the lower limit will be exceeded. This can be done by calculating emissions increases in the major high growth developing countries and the proposed emissions reductions in the major developed countries. This is not straight forward, as in most country submissions there are no clear figures, so various assumptions need to be made. For developing countries this is particularly difficult, as the estimated business as usual (BAU) emissions are usually not stated and are dependent upon assumptions of economic growth, though sometimes there are clues within the text. For the developed countries the projections are easier to calculate, as they are relative to a date in the past. There is a further issue of which measure of emissions to use. I have used the UNFCCC issued estimates of GHG emissions in its Country Briefs for 1990, 2000, 2005 & 2010.1 In many of the submissions there often both conditional and unconditional estimates of 2030 emissions. For developing countries the lower estimates are dependent on external funding. For the other countries, emissions reductions are expressed as a range. In every case I have used the lower emissions figure.2

For the developing countries, those with major projected emissions increases countries are as follows.3

Estimated targeted emissions increases from 2010 to 2030 for major developing countries based on INDC Submissions

Emissons Change

INDC Submission

Country Brief





























The targeted total increase GHG for these seven countries between 2010 and 2030 is estimated to be in excess of 13 Gt.

According to World Bank Data there were 3300 million people in these seven countries in 2013, or 46% of the global population.

For the developed countries those with the largest quantitative emissions reductions are as follows.4

Estimated targeted emissions change from 2010 to 2030 for major developed countries from INDC Submissions

Emissons Change

INDC Submission

Country Brief





















The targeted total decrease GHG for these thirty-two countries between 2010 and 2030 is estimated to be 4 Gt.

According to World Bank Data there were 900 million people in these thirty-two countries in 2013, or 13% of the global population.

For every one tonne of emissions reduction by developed countries, it will be replaced by at least three tonnes of emissions elsewhere. Bigger reductions by these developed countries will not close the gap, as their total 2010 emissions are just 12.9 G. The developing countries do not include a single African country, nor Pakistan, Iran, Venezuela, or numerous other countries. Yet it does include all the major developed countries.

Whilst the developing countries way not achieve this increase in emissions by 2030, collectively they will achieve this increase shortly after that date. Many of the developed countries may not achieve the emissions reductions due to changing priorities. For instance the EU targets reduction may not be achieved due to Germany abandoning nuclear power in favour of coal and Southern European states reducing renewables subsidies as a response to recent economic crises.

The Elephant in the Room

In 2030, even with an agreement based on the INDC submissions signed this December in Paris, and then fully implemented without compromise there is still a problem. If the IPCC models are correct, the only way to stop the 3 degrees of warming being exceeded is through rapid reductions in emissions in those countries where emissions have recently peaked (e.g. South Korea and China) along with steep reductions in emissions of countries where they are still increasing rapidly (e.g. India and Bangladesh). Unless a technological miracle happens in the next decade this is not going to happen. More likely is that global emissions may keep on rising as many slower-growing African and Asian nations have ever larger unit increases in emissions each year.

The Policy Problem

The justification for mitigation policy is most clearly laid out in the British 2006 Stern Review Summary of Conclusions page vi

Using the results from formal economic models, the Review estimates that if we don’t act, the overall costs and risks of climate change will be equivalent to losing at least 5% of global GDP each year, now and forever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20% of GDP or more.

That is the unknown and random costs of climate change can be exchanged for the lesser and predictable costs of policy. A necessary, but far from sufficient, condition of this happening is that policy will eradicate all the prospective costs of climate change. It could be that if warming is constrained to less than 2 degrees the costs of climate change would be trivial, so the reality could be a close approximation of Stern’s viewpoint. But if warming exceeds 3 degrees and the alleged harms are correct, then emissions reducing policies are likely to lead to net harms for the countries implementing those policies and a small net benefit for those countries without policy.

Kevin Marshall


  1. The exception is for Bangladesh. They are one of the few countries that clearly lays out 2030 estimates in MtCO2, but the 2010 estimate is about 20% lower than the UNFCCC figure. I have just lifted the Bangladeshi figures.
  2. For instance the USA the target is to reduce is emissions 26-28% on the 2005 level. I have used the 28% figure. The United States is about the only country not providing target figures for 2030. I would be imprudent to assume any greater reductions given that it is not certain even this level will be ratified by Congress.
  3. Not all the countries outside of the rich are targeting emissions increases. Brazil and Argentina are targeting emissions reductions, whilst Thailand and South Korea would appear to be targeting to maintaining emissions at around 2010 levels.
  4. Not all developed countries have emissions reduction targets.
  5. South Korea with 1.3% of 2010 global emissions could be included in developed countries, but its target it is to roughly maintain emissions at 2010 levels. Switzerland, Norway and Singapore are all committed to emissions reductions, but combined they have less 0.3 GT of emissions.

Theconsensusproject – unskeptical misinformation on Global Warming


Following the publication of a survey finding a 97% consensus on global warming in the peer-reviewed literature the team at “skepticalscience.com” launched theconsensusproject.com website. Here I evaluate the claims using two of website owner John Cook’s own terms. First, that “genuine skeptics consider all the evidence in their search for the truth”. Second is that misinformation is highly damaging to democratic societies, and reducing its effects a difficult and complex challenge.

Applying these standards, I find that

  • The 97% consensus paper is very weak evidence to back global warming. Stronger evidence, such as predictive skill and increasing refinement of the human-caused warming hypothesis, are entirely lacking.
  • The claim that “warming is human caused” has been contradicted at the Sks website. Statements about catastrophic consequences are unsupported.
  • The prediction of 8oF of warming this century without policy is contradicted by the UNIPCC reference.
  • The prediction of 4oF of warming with policy fails to state this is contingent on successful implementation by all countires.
  • The costs of unmitigated warming and the costs of policy and residual warming are from cherry-picking from two 2005 sources. Neither source makes the total claim. The claims of the Stern Review, and its critics, are ignored.

Overall, by his own standards, John Cook’s Consensus Project website is a source of extreme unskeptical misinformation.



Last year, following the successful publication of their study on “Quantifying the consensus on anthropogenic global warming in the scientific literature“, the team at skepticalscience.com (Sks) created the spinoff website theconsensusproject.com.

I could set some standards of evaluation of my own. But the best way to evaluate this website is by Sks owner and leader, John Cook’s, own standards.

First, he has a rather odd definition of what skeptic. In an opinion piece in 2011 Cook stated:-

Genuine skeptics consider all the evidence in their search for the truth. Deniers, on the other hand, refuse to accept any evidence that conflicts with their pre-determined views.

This definition might be totally at odds with the world’s greatest dictionary in any language, but it is the standard Cook sets.

Also Cook co-wrote a short opinion pamphlet with Stephan Lewandowsky called The Debunking Handbook. It begins

It’s self-evident that democratic societies should base their decisions on accurate information. On many issues, however, misinformation can become entrenched in parts of the community, particularly when vested interests are involved. Reducing the influence of misinformation is a difficult and complex challenge.

Cook fully believes that accuracy is hugely important. Therefore we should see evidence great care in ensuring the accuracy of anything that he or his followers promote.


The Scientific Consensus

The first page is based on the paper

Cooks definition of a skeptic considering “all the evidence” is technically not breached. With over abstracts 12,000 papers evaluated it is a lot of evidence. The problem is nicely explained by Andrew Montford in the GWPF note “FRAUD, BIAS AND PUBLIC RELATIONS – The 97% ‘consensus’ and its critics“.

The formulation ‘that humans are causing global warming’ could have two different meanings. A ‘deep’ consensus reading would take it as all or most of the warming is caused by humans. A ‘shallow’ consensus reading would imply only that some unspecified proportion of the warming observed is attributable to mankind.

It is the shallow consensus that the paper followed, as found by a leaked email from John Cook that Montford quotes.

Okay, so we’ve ruled out a definition of AGW being ‘any amount of human influence’ or ‘more than 50% human influence’. We’re basically going with Ari’s porno approach (I probably should stop calling it that) which is AGW= ‘humans are causing global warming’. e.g. – no specific quantification which is the only way we can do it considering the breadth of papers we’re surveying.

There is another aspect. A similar methodology applied to social science papers produced in the USSR would probably produce an overwhelming consensus supporting the statement “communism is superior to capitalism”. Most papers would now be considered worthless.

There is another aspect is the quality of that evidence. Surveying the abstracts of peer-reviewed papers is a very roundabout way of taking an opinion poll. It is basically some people’s opinions of others implied opinions from short statements on tangentially related issues. In legal terms it is an extreme form of hearsay.

More important still is whether as a true “skeptic” all the evidence (or at least the most important parts) has been considered. Where is the actual evidence that humans cause significant warming? That is beyond the weak correlation between rising greenhouse gas levels and rising average temperatures. Where is the evidence that the huge numbers of climate scientists have understanding of their subject, demonstrated by track record of successful short predictions and increasing refinement of the human-caused warming hypothesis? Where is the evidence that they are true scientists following in the traditions of Newton, Einstein, Curie and Feynman, and not the followers of Comte, Marx and Freud? If John Cook is a true “skeptic”, and is presenting the most substantial evidence, then climate catastrophism is finished. But if Cook leaves out much better evidence then his survey is misinformation, undermining the case for necessary action.


Causes of global warming

The next page is headed.

There is no exclusion of other causes of the global warming since around 1800. But, with respect to the early twentieth century warming Dana Nuccitelli said

CO2 and the Sun played the largest roles in the early century warming, but other factors played a part as well.

However, there is no clear way of sorting out the contribution of the relative components. The statement “the causes of global warming are clear” is false.

On the same page there is this.

This is a series of truth statements about the full-blown catastrophic anthropogenic global warming hypothesis. Regardless of the strength of the evidence in support it is still a hypothesis. One could treat some scientific hypotheses as being essentially truth statements, such as that “smoking causes lung cancer” and “HIV causes AIDS”, as they are so very strongly-supported by the multiple lines of evidence1. There is no scientific evidence provided to substantiate the claim that global warming is harmful, just the shallow 97% consensus belief that humans cause some warming.

This core “global warming is harmful” statement is clear misinformation. It is extremely unskeptical, as it is arrived at by not considering any evidence.


Predictions and Policy

The final page is in three parts – warming prediction without policy; warming prediction with policy; and the benefits and costs of policy.

Warming prediction without policy

The source info for the prediction of 8oF (4.4oC) warming by 2100 without policy is from the 2007 UNIPCC AR4 report. It is now seven years out of date. The relevant table linked to is this:-

There are a whole range of estimates here, all with uncertainty bands. The highest has a best estimate of 4.0oC or 7.2oF. They seem to have taken the highest best estimate and rounded up. But this scenario is strictly for the temperature change at 2090-2099 relative to 1980-1999. This is for a 105 year period, against an 87 year period on the graph. Pro-rata the best estimate for A1F1 scenario is 3.3oC or 6oF.

But a genuine “skeptic” considers all the evidence, not cherry-picks the evidence which suit their arguments. If there is a best estimate to be chosen, which one of the various models should it be? In other areas of science, when faced with a number of models to use for future predictions the one chosen is the one that performs best. Leading climatologist, Dr Roy Spencer, has provided us with such a comparison. Last year he ran 73 of the latest climate CIMP5 models. Compared to actual data every single one was running too hot.

A best estimate on the basis of all the evidence would be somewhere between zero and 1.1oC, the lowest figure available from any of the climate models. To claim a higher figure than the best estimate of the most extreme of the models is not only dismissing reality, but denying the scientific consensus.

But maybe this hiatus in warming of the last 16-26 years is just an anomaly? There are at possibly 52 explanations of this hiatus, with more coming along all the time. However, given that they allow for natural factors and/or undermine the case for climate models accurately describing climate, the case for a single extreme prediction of warming to 2100 is further undermined. To maintain that 8oF of warming is – by Cook’s own definition – an extreme case of climate denial.

Warming prediction with policy

If the 8oF of predicted human-caused warming is extreme, then a policy that successfully halves that potential warming is not 4oF, but half of whatever the accurate prediction would be. But there are further problems. To be successful, that policy involves every major Government of developed countries reducing emissions by 80% (least including USA, Russia, EU, and Japan) by around 2050, and every other major country (at least including Russia, China, India, Brazil, South Africa, Indonesia and Ukraine) constraining emissions at current levels for ever. To get all countries to sign-up to such a policy combatting global warming over all other commitments is near impossible. Then take a look at the world map in 1925-1930 and see if you could reasonably have expected those Governments to have signed commitments binding on the Governments of 1945, let alone today. To omit policy considerations is an act of gross naivety, and clear misinformation.

The benefits and costs of policy

The benefits and costs of policy is the realm of economics, not of climatology. Here Cook’s definition of skeptic does not apply. There is no consensus in economics. However, there are general principles that are applied, or at least were applied when I studied the subject in the 1980s.

  • Modelled projections are contingent on assumptions, and are adjusted for new data.
  • Any competent student must be aware of the latest developments in the field.
  • Evaluation of competing theories is by comparing and contrasting.
  • If you are referencing a paper in support of your arguments, at least check that it does just that.

The graphic claims that the “total costs by 2100” of action are $10 trillion, as against $20 trillion of inaction. The costs of action are made up of more limited damages costs. There are two sources for this claim, both from 2005. The first is from “The Impacts and Costs of Climate Change”, a report commissioned by the EU. In the Executive Summary is stated:-

Given that €1.00 ≈ $1.20, the costs of inaction are $89 trillion and of reducing to 550ppm CO2 equivalent (the often quoted crucial level of 2-3 degrees of warming from a doubling of CO2 levels above pre-industrial levels) $38 trillion, the costs do not add up. However, the average of 43 and 32 is 37.5, or about half of 74. This gives the halving of total costs.

The second is from the German Institute for Economic Research. They state:-

If climate policy measures are not introduced, global climate change damages amounting to up to 20 trillion US dollars can be expected in the year 2100.

This gives the $20 trillion.

The costs of an active climate protection policy implemented today would reach globally around 430 billion US dollars in 2050 and around 3 trillion US dollars in 2100.

This gives the low policy costs of combatting global warming.

It is only by this arbitrary sampling of figures from the two papers that the websites figures can be established. But there is a problem in reconciling the two papers. The first paper has cumulative figures up to 2100. The shorthand for this is “total costs by 2100“. The $20 trillion figure is an estimate for the year 2100. The statement about the policy costs confirms this. This confusion leads the policy costs to be less than 0.1% of global output, instead of around 1% or more.

Further the figures are contradicted by the Stern Review of 2006, which was widely quoted in the UNIPCC AR4. In the summary of conclusions, Stern stated.

Using the results from formal economic models, the Review estimates that if we don’t act, the overall costs and risks of climate change will be equivalent to losing at least 5% of global GDP each year, now and forever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20% of GDP or more.

In contrast, the costs of action – reducing greenhouse gas emissions to avoid the worst impacts of climate change – can be limited to around 1% of global GDP each year.

The benefit/cost ratio is dramatically different. Tol and Yohe provided a criticism of Stern, showing he used the most extreme estimates available. A much fuller criticism is provided by Peter Lilley in 2012. The upshot is that even with a single prediction of the amount and effects of warming, there is a huge range of cost impacts. Cook is truly out of his depth when stating single outcomes. What is worse is that the costs and effectiveness of policy to greenhouse emissions is far greater than benefit-cost analyses allow.



To take all the evidence into account and to present the conclusions in a way that clearly presents the information available, are extremely high standards to adhere to. But theconsensusproject.com does not just fail to get close to these benchmarks, it does the opposite. It totally fails to consider all the evidence. Even the sources it cites are grossly misinterpreted. The conclusion that I draw is that the benchmarks that Cook and the skepticalscience.com team have set are just weapons to shut down opponents, leaving the field clear for their shallow, dogmatic and unsubstantiated beliefs.

Kevin Marshall



  1. The evidence for “smoking causes lung cancer” I discuss here. The evidence for “HIV causes AIDS” is very ably considered by the AIDS charity AVERT at this page. AVERT is an international HIV and AIDS charity, based in the UK, working to avert HIV and AIDS worldwide, through education, treatment and care. – See more here.
  2. Jose Duarte has examples here.

Why Climate Change Mitigation Policies Will Always Fail

All climate mitigation policies will be of net harm to any country implementing them. There are three reasons for this.

First, mitigation policies will not eliminate all the projected harm of climate change. Policy replaces the unmitigated cost of climate change with a policy cost and a residual climate change cost.

Second, policy proposals are only for the rich countries to reduce emissions and emerging economies to constrain the growth. That means residual climate change costs will be greater, and the burden of cost of reductions will fall on a number of countries will a minority of, and a rapidly diminishing share of, global emissions. Even with the rich nations all succeeding in the British target of 80% reduction by 2050 will still mean global emission levels higher than currently.

Third, there is mounting evidence that actual mitigation costs per tonne of CO2 equivalent saved are considerably more than the economic models assume.



The Stern Review Summary of Conclusions stated on page vi

Using the results from formal economic models, the Review estimates that if we don’t act, the overall costs and risks of climate change will be equivalent to losing at least 5% of global GDP each year, now and forever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20% of GDP or more.

In contrast, the costs of action – reducing greenhouse gas emissions to avoid the worst impacts of climate change – can be limited to around 1% of global GDP each year.

The Review further stated on pages xvi-xvii

Preliminary calculations adopting the approach to valuation taken in this Review suggest that the social cost of carbon today, is of the order of $85 per tonne of CO2……. This number is well above marginal abatement costs in many sectors.

Many objections to the report look at the cost of climate change. Little discussed are the theoretical issues in implementing a successful policy. By “successful” I mean where the expected outturn of the policy is less than the projected costs of climate change.


The basic case

As the Stern review is saying that globally we should replace one set of costs – the projected costs of climate change – will the much lesser costs of climate. Graphically, we replace the climate change costs in blue with policy costs in orange. Costs are positive and benefits negative.

The case for policy is clear.


Climate change costs not completely eliminated

Peter Lilley, in his 2012 GWPF report “WHAT IS WRONG WITH STERN?” states on page 8

The benefit of preventing (climate change) entirely would, on his figures, be at least 5% of GDP – but to do so would require not just stopping all further carbon emissions but removing all those accumulated since the industrial revolution. The action he proposes to reduce the worst impacts of global warming by stabilising the atmospheric concentration of greenhouse gases at 550 ppm would, using Stern’s methodology, save some 3.1% of GDP – not 5%.

The mitigation policy seeks to stabilize total greenhouse gas levels are a level equivalent to about double the level of CO2 in 1780.

The case for policy is still clear.


Rich Countries Policy Burden

It is accepted that

  1. Rich countries are responsible for most of climate change.
  2. The adverse consequences of unmitigated climate change will be disproportionately endured by the less developed nations (LDNs).

Therefore the moral argument is that the rich countries should bear the cost of policy and they should compensate the LDNs for the future harm that they will endure. The compensation could then be used to offset the harm of climate change.

Rich countries have a smaller population than the LDNs. The policy costs (in orange) for them will more than double. Similarly, compensation (in burnt orange) will be much larger for the rich countries to pay out than for the LDNs who receive it in income. Finally the post-policy climate change costs (in blue) will be still larger for the LDNs.

The rich countries may or may not be better off after policy. Further the LDNs still suffer some harm.


Increasing Emissions amongst the emerging nations

Policy must include the emerging nations. This is why.

I have arbitrarily split the countries of the World into three groups

  1. ACEJU – The big industrialised carbon emitters – Australia, Canada, EU, Japan and USA.
  2. BICS – The large emerging nations of Brazil, India, China and South Africa.
  3. ROW – Rest of the World.

The World Bank has data on CO2 emissions by country for the period 1990 to 2010. From this, I compiled the following graph.

In the period 1990 to 2010, annual global CO2 emissions increased by 11.4 billion tonnes, or 51%. To return to 1990 emissions levels would require one group to cease emissions entirely and the other two groups to maintain emissions at 2010 levels. The future emissions growth path potentially makes the problem worse. Consider the comparative growth in population.

Despite the BICS countries increasing its emissions by 230%, emissions per capita are still less than 40% of those of the ACEJU block. Further, the explosive growth of the BICS has not been matched by the Rest of the World. Here the emissions have grown by 45%, but population has grown by 42%. Emissions per capita are still only 35% of those of the AJEJU block.

Any policy reductions by the rich nations will be more than offset by future emissions growth in the rest of the world. There will be little reduction in climate change costs, for either the policy countries or non-policy countries. The situation becomes like this.

The non-policy countries will still see a reduction, but that might be small, even if the policy countries are successful. The disadvantage to the policy countries is inversely related to proportion of global emissions they have at the end of the policy. That in turn is influenced by the future emissions growth in the non-policy countries, as well as the proportion of global emissions in a baseline year.


Peer-reviewed costs of Climate Change and Actual Costs of Mitigation

The Stern review should not be taken as the only source. The UNIPCC AR4 Summary for Policymakers in 2007 stated on page 22.

Peer-reviewed estimates of the social cost of carbon in 2005 average US$12 per tonne of CO2, but the range from 100 estimates is large (-$3 to $95/tCO2).

The average social cost is just a seventh of the Stern Review, which was not a study that has been peer-reviewed.

In a previous posting, I calculated that the subsidy of offshore wind farms was equivalent to 3.8 times Stern’s social cost of carbon, and 27 times that of the $12 average of peer-reviewed studies quotes by the UNIPCC. This was a low estimate, not including transmission costs. There might be cheaper ways of abating CO2, but there are lot of failed policies as well. There is also the impact on economic growth to consider, which for emerging economies. So a more realistic situation of a “successful” mitigation policy will look like the one below. That is “successful” in achieving the emission reduction targets.

Points for further investigation

There are a number of issues that are raised in my mind that need further work.

  1. The social cost of carbon defines the expected harm from climate change per tonne of CO2. If a country has quantitative emissions reduction targets, then an absolute upper limit in annual spend can be defined when achieving that target.
  2. This would enable identification of the success of policies within a national plan, along with the overall success of that plan.
  3. The expected CO2 emissions growth in non-policy countries, along with including other greenhouse gas emissions within the analysis.



There is no combination of mitigation policies that can produce a less costly outcome than doing nothing. Any government unilaterally (or as part of group representing a minority of global emissions) pursuing such policies will be imposing net harm on its own people, no matter how large the claimed potential impacts of climate change. This conclusion can be reached even if the extreme views of the Stern Review are taken as the potential costs of climate change.

Kevin Marshall



The comparison of emissions growth between countries is derived from “The Climate Fix” by Roger Pielke Jnr. This enlarges on a comment made at Australian Climate Madness blog.

All first time comments are moderated. Please use the comments as a point of contact.

Update 25/02 17.30. Summary and “Points for further investigation” included, along with text changes

10GW of extra offshore wind turbines by 2020 – The Real Costs

Projected 10GW in offshore wind turbines by 2020 to add 5% to electricity and gas bills, and reduce UK CO2 emissions by nearly 2%. Cost to exceed benefits by 3.8 or 27 times.


The Telegraph has an article “Offshore wind farm scrapped due to fears over birds

A 200MW extension to the 630MW London Array has been abandoned “over the impact on the red-throated diver, a bird classified as rare or vulnerable by the European Commission“. However,

Ministers say they want between 8GW and 15GW built by 2020, up from 3.6GW now, and suggest a total of about 10GW is most likely.

My comment on this (with references) is

Some statistics to put the 10GW of extra offshore wind power by 2020 in perspective.

Offshore wind power operates at about 35% of nameplate from DECC figures1.

So that will produce about 30,660,000 Mwh of electricity.

At present each megawatt of offshore wind gets 2 renewables obligations certificates, worth £842,8. So that will add £2575m to bills, or about 5%3 of 2012 Electricity AND Gas bills.

But this will help reduce the UKs Carbon emissions. How much?

RenewableUK reckons that each megawatt hour of renewable electricity saves 430kg of CO2 emissions4. So that equates to 13.2 mt, or 1.84% of the 716.4 mt6 1990 baseline emissions.

This has a value as well, called the “social cost of carbon”. The Stern Review reckoned $85t/CO25. The UNIPCC said the average was $126. So that is £675m or £95m towards saving the planet for future generations. Costs are either 3.8 or 27 times the benefits.


The costs of £2575m are not the full costs. There are also extra transmission costs, and backup capacity. A more sceptical view would put a much lower social cost of carbon than the $12 of the UNIPCC.

From note 5, the marginal abatement costs of offshore wind turbines are 3.8 times Stern’s estimate. Perhaps somebody should ask Lord Stern where the marginal abatement costs of less than $85 per tonne of CO2 are to be found. There are millions of households and businesses in this country who would love to know.


  1. DECC stats here, spreadsheet “Renewable electricity capacity and generation (ET 6.1)”. Offshore wind was 35.2% of nameplate in 2012.
  2. https://www.ofgem.gov.uk/ofgem-publications/58136/buy-out-price-and-mututalisation-ceiling-201314.pdf.
  3. In 2012 the big six energy companies charged about £44bn to all customers. 5% rise assumes they have 85% of the market. Graph here, from this article.
  4. From http://www.renewableuk.com/en/renewable-energy/wind-energy/uk-wind-energy-database/figures-explained.cfm, last section “CO2 Reductions (p.a.) in Tonnes”.
  5. The Stern review noted on pages xvi-xvii

    Preliminary calculations adopting the approach to valuation taken in this Review suggest that the social cost of carbon today, is of the order of $85 per tonne of CO2……. This number is well above marginal abatement costs in many sectors.

  6. The UNIPCC AR4 Summary for Policymakers in 2007 stated on page 22.

    Peer-reviewed estimates of the social cost of carbon in 2005 average US$12 per tonne of CO2, but the range from 100 estimates is large (-$3 to $95/tCO2).

  7. Source World Bank data. UK data at http://data.worldbank.org/country/united-kingdom
  8. The current banding is at https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/211292/ro_banding_levels_2013_17.pdf

First-time comments are moderated. Please use the comments as a point of contact, stating this is the case.

Kevin Marshall






The Nub of the Climate Change Policy Problem

Over at the Conversation, Climate Scientist Mike Hulme has a short article “Science can’t settle what should be done about climate change“. He argues the politics, not science, must take centre stage. He makes four points.

  • How do we value future public goods and natural assets relative to their value today?
  • Is “commodifying” nature appropriate?
  • The morality of technologies for mitigation or adaptation. For instance, fracking and GM crops.
  • The role of national governments against multilateral treaties or international governing bodies. Also the consequent impacts on democracy.

Christopher Wright (Professor of Organisation Studies at University of Sydney) commented

The one problem I have with the above analysis is that the focus on climate science has been a quite deliberate strategy by those seeking to deny or cast doubt on the urgency of the problem. This has meant the debate has continually stalled around issues of whether climate change is a problem or not. The science highlights that it is a very big problem indeed. However, while the science continues to be questioned, we will be unable to have the serious policy conversation about what we need to do to avoid catastrophic changes to our ecosystem.

My reply (with references) is

Science might point to a very big problem, but it cannot translate that into coherent policy terms. Nor can it weigh that against the effectiveness of policies, nor the harms policies can cause. Economics is central to asking those questions. The key figure that encapsulates the predicted harm of climate change is the social cost of carbon SCC, expressed in tonnes of CO2 equivalent. In 2006 Stern measured this as $85/tCO21. A year later the AR4 SPM2 stated a range of -$3 to $95/tCO2 from peer reviewed studies, with an average of $12/tCO2.

The key figure for the effectiveness to policy is the marginal abatement cost. Basically this refers to the marginal cost of preventing a tonne of CO2 equivalent entering the atmosphere. For policy to be of net benefit, MAC needs to be less than SCC.

$85 is about £52, and $12 about £7.50. In the UK onshore wind turbines receive a direct subsidy equivalent to £98/tCO23 saved, and offshore £195/tCO2. Then there are the extra costs of transmission lines, and other costs which could double those figures.

Then you need to recognize that a global problem will not be solved by unilateralist policies by a country with producing less than 2% of global emissions. So the UK is impoverished now by harmful, ineffectual, policies, and still future generations suffer >90% of the consequences of unmitigated climate change. Mike Hulme’s four points above are in addition to this, weighing further against mitigation policy.


  1. The Stern review noted on pages xvi-xvii

    Preliminary calculations adopting the approach to valuation taken in this Review suggest that the social cost of carbon today, is of the order of $85 per tonne of CO2……. This number is well above marginal abatement costs in many sectors.

  2. The UNIPCC AR4 Summary for Policymakers in 2007 stated on page 22.

    Peer-reviewed estimates of the social cost of carbon in 2005 average US$12 per tonne of CO2, but the range from 100 estimates is large (-$3 to $95/tCO2).

  3. The renewables obligation credit (ROC) buy-out price is currently £42.02 per megawatt hour, as determined by OFGEM. The British renewable industry lobby group renewableUK, uses DECC’s carbon saving figure of 430g/kWh, as stated in an appendix to the Energy Efficiency Innovation Review in 2005. £42.02/.430 = £97.67. Onshore wind turbines get one ROC per MWh generated, offshore wind turbines 2 ROCs.

Kevin Marshall

Jo Nova discusses Mike Hulme’s four points here.

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

Costs of Climate Change in Perspective

This is a draft proposal in which to frame our thinking about the climatic impacts of global warming, without getting lost in trivial details, or questioning motives. This builds upon my replication of the thesis of the Stern Review in a graphical form, although in a slightly modified format.

The continual rise in greenhouse gases due to human emissions is predicted to cause a substantial rise in average global temperatures. This in turn is predicted to lead severe disruption of the global climate. Scientists project that the costs (both to humankind and other life forms) will be nothing short of globally catastrophic.

That is

CGW= f {K}                 (1)

The costs of global warming, CGW are a function of the change in the global average surface temperatures K. This is not a linear function, but of increasing costs per unit of temperature rise. That is

CGW= f {Kx} where x>1            (2)


The curve is largely unknown, with large variations in the estimate of the slope. Furthermore, the function may be discontinuous as, there may be tipping points, beyond which the costly impacts of warming become magnified many times. Being unknown, the cost curve is an expectation derived from computer models. The equation thus becomes

E(CGW)= f {Kx}                (3)

The cost curve can be considered as having a number of elements the interrelated elements of magnitude M, time t and likelihood L. There are also costs involved in taking actions based on false expectations. Over a time period, costs are normally discounted, and when considering a policy response, a weighting W should be given to the scientific evidence. That is

E(CGW)=f {M,1/t,L,│Pr-E()│,r,W}    (4)

Magnitude M is the both severity and extent of the impacts on humankind or the planet in general.

Time t is highly relevant to the severity of the problem. Rapid changes in conditions are far more costly than gradual changes. Also impacts in the near future are more costly than those in the more distant future due to the shorter time horizon to put in place measures to lessen those costs.

Likelihood L is also relevant to the issue. Discounting a possible cost that is not certain to happen by the expected likelihood of that occurrence enables unlikely, but catastrophic, events to be considered alongside near certain events.

│Pr-E()│ is the difference between the predicted outcome, based on the best analysis of current data at the local level, and the expected outcome, that forms the basis of adaptive responses. It can work two ways. If there is a failure to predict and adapt to changing conditions then there is a cost. If there is adaptation to anticipation future condition that does not emerge, or is less severe than forecast, there is also a cost. │Pr-E()│= 0 when the outturn is exactly as forecast in every case. Given the uncertainty of future outcomes, there will always be costs incurred would be unnecessary with perfect knowledge.

Discount rate r is a device that recognizes that people prioritize according to time horizons. Discounting future costs or revenue enables us to evaluate the discount future alongside the near future.

Finally the Weighting (W) is concerned with the strength of the evidence. How much credence do you give to projections about the future? Here is where value judgements come into play. I believe that we should not completely ignore alarming projections about the future for which there is weak evidence, but neither should we accept such evidence as the only possible future scenario. Consider the following quotation.

There are uncertain truths — even true statements that we may take to be false — but there are no uncertain certainties. Since we can never know anything for sure, it is simply not worth searching for certainty; but it is well worth searching for truth; and we do this chiefly by searching for mistakes, so that we have to correct them.

Popper, Karl. In Search of a Better World. 1984.

Popper was concerned with hypothesis testing, whilst we are concerned here with accurate projections about states well into the future. However, the same principles apply. We should search for the truth, by looking for mistakes and (in the context of projections) inaccurate perceptions as well. However, this is not to be dismissive of uncertainties. If future climate catastrophe is the true future scenario, the evidence, or signal, will be weak amongst historical data where natural climate variability is quite large. This is illustrated in the graphic below.

The precarious nature of climate costs prediction.

Historical data is based upon an area where the signal of future catastrophe is weak.

Projecting on the basis of this signal is prone to large errors.

In light of this, it is necessary to concentrate on positive criticism, with giving due weighting to the evidence.

Looking at individual studies, due weighting might include the following:-

  • Uses verification procedures from other disciplines
  • Similarity of results from using different statistical methods and tests to analyse the data
  • Similarity of results using different data sets
  • Corroborated by other techniques to obtain similar results
  • Consistency of results over time as historical data sets become larger and more accurate
  • Consistency of results as data gathering becomes independent of the scientific theorists
  • Consistency of results as data analysis techniques become more open, and standards developed
  • Focus on projections on the local level (sub-regional) level, for which adaptive responses might be possible

To gain increased confidence in the projections, due weighting might include the following:-

  • Making way-marker predictions that are accurate
  • Lack of way-marker predictions that are contradicted
  • Acknowledgement of, and taking account of, way-marker predictions that are contradicted
  • Major pattern predictions that are generally accurate
  • Increasing precision and accuracy as techniques develop
  • Changing the perceptions of the magnitude and likelihood of future costs based on new data
  • Challenging and removal of conflicts of interest that arise from scientists verifying their own projections

    Kevin Marshall