On Matt Ridley’s latest attempt at climate change denial

Note: Matt Ridley has responded – please see his reply piece here

Matt Ridley’s latest column in the Times illustrates a persistent theme for those who oppose action on climate change: that cuts in carbon emissions intended to reduce the dangers of global warming are somehow code for a war against the poor. Climate sceptics use this logic to claim the moral high ground in their own war against policies to cut back on fossil fuel burning. They defend the high-carbon consumption of the rich, in other words, purportedly to assist in the development prospects of the billion people in poorer countries who still don’t have access to electricity. If this sounds strange, it’s because it is.

Biofuels mistake

Ridley’s piece (paywalled here, free version on his website here) complains about “eco-toffs” promoting socially regressive carbon mitigation policies and maintains that “the cost of climate policies falls heavily on today’s poor”. Strangely, one of his key examples to justify this claim is that “subsidies for biofuels have raised food prices by diverting food into fuel, tipping millions into malnutrition and killing about 190,000 people a year”.

Whoops! I don’t know any green groups, however aggressively they may promote carbon cuts, that still promote subsidies for biofuels that might compete with food production on land. Greenpeace calls land-based biofuels “a dead-end path”. ActionAid UK, which strongly promotes action on climate change, recently had a whole campaign called ‘Food not fuel‘, saying: “The rush for biofuels is pushing millions into hunger. It’s madness that we burn food in our cars as biofuels whilst 1 in 8 go hungry.” I’m sure Ridley would agree, as would I. There is a UK-based environmental campaign group called Biofuelwatch that frequently campaigns against biomass in power stations being classed as a subsidised ‘renewable’ fuel. Friends of the Earth makes similar points.

Ridley maintains that “Greens think this harm is a price worth paying to stop the warming”. This is clearly not the case when it comes to biofuels, not least because there is abundant evidence now that the most unsustainably harvested biofuels (such as palm oil on ex-rainforest land in Malaysia, or biomass pellets from North American clear-cuts) are many times worse than fossil fuels even in straight carbon terms. When their biodiversity and social impacts (competing against food production for humans) are factored in the case against becomes even stronger. Actually this is one of the few areas where climate sceptics and greens seem to agree – something to acknowledge and build on perhaps!

Climate paradoxes

But this is only the beginning. Unfortunately, because Ridley has convinced himself that cuts to carbon emissions will harm the world’s poor, he feels the need to craft ‘scientific’ justifications for his clearly intuitive belief that global warming will not be so bad. (More likely, it’s the other way round: he’s against tackling global warming, and wants to use the world’s poor as a moral justification for this.)

Let me say at the outset that I don’t even think this is logical. It is quite possible (maybe even probable) for global warming to both be extremely damaging and for near-term carbon emissions cuts to have a harmful effect on the world’s poor. Ridley mentions in his piece the “3.5 million deaths a year from indoor air pollution caused by cooking over open fires of wood and dung”. I agree with this figure; indeed the latest estimates from the World Health Organisation (WHO) are as many as 4.3 million premature deaths a year are likely attributable to “pollution exposures among the estimated 2.9 billion people living in homes using wood, coal or dung as their primary cooking fuel”.

I entirely accept that these peoples’ lives would be much improved by using electric cooking in the home (or much cleaner gas) even if this electricity were to come from new coal-fired power stations in places like India and Bangladesh, thereby worsening carbon emissions and the resulting global warming. (Though one should bear in mind WHO’s figure of 3.7 million annual deaths worldwide from outdoor air pollution, of which coal burning is by far the largest source.)

This is a familiar paradox, and one that has been pointed out by many people (e.g. Breakthrough Institute and Roger Pielke Jnr. There is no doubt that global energy production is going to have to double, triple or even quadruple this century in order to allow for economic development and poverty eradication worldwide. This is one of the reasons I have supported nuclear power, which along with renewables can offset the use of coal and other fossil fuels in producing this much-needed increase in energy supplies.

Wishing away global warming

What bugs me however is that Ridley resolves this paradox instead by denying the gravity of global warming. He does this by rejecting the seven-year-long effort of the IPCC to come up with a consensus position on future global warming estimates, and instead cherry-picking a couple of studies that seem to support lower warming projections to bolster his pre-determined position.

Here’s Ridley’s key paragraphs in the Times article:

But is greenery really quite so selfless? Take climate change. The “synthesis report” of the Intergovernmental Panel on Climate Change, published yesterday, warns of an increased “likelihood” of severe, pervasive and irreversible impacts if emissions continue. But when you cut through the spin, the IPCC is actually saying that there is a range of possibilities, from no net harm at all (scenario RCP 2.6) through two middling scenarios to one where gathering harm from mid-century onwards culminates in potentially dire consequences by 2100 (scenario RCP 8.5).

This latter scenario makes wildly unrealistic assumptions about population, coal use, trade, methane emissions and other things; RCP 2.6 is equally unrealistic in the other direction. So let’s focus on the two middle scenarios, known as RCP 4.5 and RCP 6. In these more realistic economic projections, if you use the latest and best estimates of the climate’s “sensitivity” to carbon dioxide (starkly lower than the out-of-date ones still used by the IPCC), the most probable outcome is that the world will be respectively just 0.8 and 1.2 degrees Celsius warmer than today by the last decades of this century.

Most of that warming will be at night, in winter and in northern latitudes, so tropical daytime warming will be less. Again, on the best evidence available, it is unlikely that this amount of warming, especially if it is slow, will have done more harm than good. The chances are, therefore, that climate change will not cause significant harm in the lives of our children and grandchildren.

When challenged by me on Twitter Ridley did cite a couple of references:

Ridley’s scientifically unsupportable claims

Now let’s go through this and see where Ridley’s ideological bias is pushing him into making scientifically unsupportable claims. Ridley rejects both the very high and very low emission scenarios of the IPCC as being “unrealistic”. I agree the low-emission RCP 2.6 scenario, which sees a peak in global emissions in about 6 years from now, and then negative emissions after about 2070, is indeed unrealistic. It is very difficult to square this with rapid economic growth in developing countries and the energy consumption growth that must support it.

However, I do not see any a priori reason to reject RCP 8.5, the highest-emissions scenario considered by the IPCC, not least because that is the scenario world emissions are currently tracking slightly above, as this graph – which plots historical emissions against all the RCPs – demonstrates.

From Sandford, T. et al, 'The climate policy narrative for a dangerously warming world', Nature Climate Change, http://www.nature.com/nclimate/journal/v4/n3/full/nclimate2148.html
From Sandford, T. et al, 2014: ‘The climate policy narrative for a dangerously warming world’, Nature Climate Change, http://www.nature.com/nclimate/journal/v4/n3/full/nclimate2148.html

That’s Ridley’s first sleight of hand. But the second is far worse. Armed with the two scenarios RCP 4.5 and RCP 6 that he considers ‘realistic’, Ridley then ignores the IPCC’s projected warming responses and substitutes his own, which just happen to be “starkly lower than the out-of-date ones still used by the IPCC”. In other words, Ridley cherry-picks a couple of studies which project lower ‘equilibrium climate sensitivity’ (ECS), superimposes them on RCPs 4.5 and 6, and hey presto! – he has low enough figures for global warming this century in order to conclude “that climate change will not cause significant harm in the lives of our children and grandchildren”.

I have to admit this drove me to sarcasm on Twitter:

Consensus science

But really. What is the point of the entire 7-year IPCC process, assessing thousands of papers in the peer-reviewed literature, assembling hundreds of experts to author chapters and then pick through them line by line, if the resulting report (and the Synthesis Report was just launched this week) can then be dismissed by right-wing newspaper columnists as merely “out of date”?

To me the value of consensus science is just that: by dint of a weighty literature review it rules out cherry-picking. I accept that Ridley has written knowledgeably about evolutionary biology and many other things in the past, but on climate change he blows away any claim to scientific credibility with this extraordinary dismissal of the vast majority of the evidence in order to bolster a pre-conceived ideological position. I believe this is called ‘motivated reasoning’ by psychologists.

And he doesn’t even get it right. Yes, Lewis and Curry (one of Ridley’s cherry-picked citations linked in his tweet above) come up with a much lower estimate for equilibrium climate sensitivity, but ECS is a fairly academic value anyway – it imagines the equilibrium response of the climate system, meaning many centuries away from today. (In reality true equilibrium would never be reached as the climate is a dynamic system subject to multiple and always-changing forcings, both natural and anthropogenic.)

The temperature value that we all actually care about is called transient climate response (TCR), which is how much global warming we might expect, in Ridley’s words, “in the lives of our children and grandchildren”. And as has been pointed out elsewhere (including by the IPCC – see Fig TS6.2, p.84 here), Lewis and Curry’s estimates for TCR are pretty much in line with everyone else’s. So Ridley, blinded by his ideological fervour, has plucked the wrong cherry.

Here’s the relevant graph for TCR for the various RCP scenarios. I have taken it from a 2014 Nature Geoscience paper by David Frame, Adrian Macey and Myles Allen, so it’s not, er, ‘out of date’. The IPCC version of this graph can be viewed in the Synthesis Report – see Figure 2.3 in this PDF – but it’s rather low-resolution and difficult to read.

From Frame et al, 2014: 'Cumulative emissions and climate policy', Nature Geoscience, http://www.nature.com/ngeo/journal/v7/n10/full/ngeo2254.html
From Frame et al, 2014: ‘Cumulative emissions and climate policy’, Nature Geoscience, http://www.nature.com/ngeo/journal/v7/n10/full/ngeo2254.html

A killer mistake

As the IPCC makes clear, transient climate response is very much a function of cumulative carbon emissions, and actually has very little to do with whatever your idealised value is for equilibrium climate sensitivity many centuries away. If you read off the graph, RCP 4.5 gives us about 2.4C global warming by 2100 (not 0.8C as Ridley maintains), while RCP 6 takes us to about 3 degrees C (more than double Ridley’s 1.2C). If we include the scenarios Ridley rejected, only the lowest, RCP 2.6, stays under 2 degrees, the internationally-agreed objective for mitigating global warming, whilst the highest, RCP 8.5, takes us well over 4 degrees C.

Now, I wrote a book a few years back called Six Degrees, which looked at the likely impacts of each degree of warming. I won’t prescis it here, but let me say that 2 degrees was bad, four degrees was catastrophic, and six degrees was pretty much unimaginable (though I did try). Because of this, and because I have children myself, I would be delighted if Ridley was right and global warming could be easily restrained to just 0.8C. Unfortunately, I don’t think we’re going to achieve this by wishing away consensus science and inventing our own convenient alternative. There’s a word for this: it’s called ‘denial’. We have to deal with the world as it is, not how we’d wish it to be.

© Mark Lynas
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