Matt Ridley interviewed by Roger Harrabin

Matt Ridley Interview [RH: = Roger Harrabin

MR: = Matt Ridley]

RH: Matt Ridley, thank you very much for agreeing to be interviewed for a combination of the Open University and BBC. It’s a great pleasure to talk to you. We’re asking everybody, for the first question, when their interest in energy was first kindled. I suspect your story may be slightly different to everybody else’s. MR: Well, yes and no. I got very interested in the climate story when I was covering it for The Economist in the late eighties, early nineties. RH: I’m thinking way back from then, because very few people have a coal mine on their land! MR: Yes, although the coal mine’s relatively recent, but I grew up in a coal mining area, and I’m descended from a long line … well not recently, but in the eighteenth century one of my ancestors was pioneer of coal mining in Newcastle and indeed put the first steam engine into a coal mine on the north bank of the Tyne so was right there at the beginning of the industrial revolution. So yes – I have a – RH: So that’s there in your family history. Do you – MR: I have an affection for what coal did for humanity and I occasionally feel like standing up for it. I try and be dispassionate about it, I always declare that I have, currently, an interest in coal mining. It doesn’t actually last for very much longer, another couple of years and then I get no money from coal mining and then I can say what I really think, which is that coal is wonderful! RH: OK, well – MR: RH: Let’s get back onto that in a moment, because I’d like to start, if you would, with your history on climate change, because you’ve moved about a bit, can you just talk us through your journey? MR: Well I first came across the climate change debate in 1987 or so, working for The Economist, and I was alarmed. I looked at the numbers people were saying, I looked at the increasing carbon dioxide levels, looked at the Jani equation for how

Commented [CB1]: Carbon Brief [1]: Transcription error. This should read “Charney equation”. It refers to the findings of a National Academy of Science report in 1979 on carbon dioxide and the climate, chaired by Jules Charney.

much warming this was likely to produce, and reported it straight, as it were, as a very alarming prospect. I became a little more sceptical in the nineties when I began to look into the science a bit more closely, but then I kind of drifted off and went off and wrote about genes for a number of years and didn’t pay any attention; then the hockey stick graph hit me between the eyes. When I first saw that I can remember I was at a farming conference, someone showed this hockey stick graph, Mann et al. 1999, and I thought wow! I was wrong to be sceptical, this is really scary, because it’s clearly unprecedented, it bears no relation to what’s happened at the Medieval warm period and that kind of thing, and so when in the following years I’ve discovered – RH: So you wrote about it at that point?

Commented [CB2]: Carbon Brief [2]: The ‘Hockey Stick’ refers to a graph of temperature over the past 1,000 years, reconstructed from tree rings, ice cores, corals and other proxy records. The graph was first published in a paper by Mann, Bradley & Hughes in 1999 (hereafter referred to as MBH99). Commented [CB3]: Carbon Brief [3]: ‘Medieval Warming Period’ or ‘Medieval Climate Anomaly’ refers to a time between 950-1250AD during which the IPCC says temperatures in some regions, but not globally, were as warm as in the late 20th century (WG1 SPM p3).

MR: No I didn’t, I wasn’t writing about climate change either way much at that point, but when I did touch on it, I didn’t demure from the consensus. RH: Intellectually you were convinced. MR: I thought I’d made a mistake by being sceptical, put it like that. But then I came across Steve McIntyre’s work on the hockey stick, and the further I dug into that and Andrew Montford’s distillations of it –

Carbon Brief [4]: In 2005, Steve McIntyre and Ross Commented [CB4]: McKitrick published a critique of the techniques used in Mann et al. (1999) Their critique was, in turn, disputed by subsequent studies (see comment [6] below).

RH: I should say these are two bloggers, and very well-informed bloggers.

[Cont…]

MR: Exactly, well Steve McIntyre’s a Canadian mathematician who had the hockey stick put through his letterbox by the Canadian government and thought, ‘Hang on – this graph doesn’t look right’, and the more he looked into it the more he dug up that’s wrong with it. And basically now there’s very few people who think that graph is correct i.e. that the rate of change today is dramatically different from anything in the past, and that the level of temperature is dramatically different from things in the past 1,000 years, we’re talking about. So the undermining of the hockey stick was therefore all the more important, because it had been the thing that had persuaded me to take this issue seriously. But it was simply the beginning of going on looking into more and more of the climate story and finding that more and more of the

Commented G Schmidt [GS5]: [5]: Actually, the issues raised mainly only impacted the last step in the procedure (14001450) and were clearly shown in Wahl and Amman (2007) not to make any substantive difference to the form or substance of the Mann et al. results. Commented G Schmidt [GS6]: [6]: Ridley is creating a strawman. The original Mann, Bradley & Hughes paper only covered 600 years, and made no claim that the rate of change now is 'dramatically different from anything in the past'. The MBH99 extension to 1,000 years also did not make this claim (obviously since these are just reconstructions for a small part of the past). The best updates since then - which include both methodology improvements and expanded data sources - do not show anything dramatically different to the basic picture shown in MBH.

G Schmidt [GS7]: [7]: I can't comment on what led to Commented Ridley's supposed conversion, but since better papers have come along with more or less the same results I cannot follow his logic, even if he thinks the absolute worst about the MBH papers themselves.

alarming … stories didn’t seem to add up; that actually the evidence for a gentle warming as a result of carbon dioxide produced by man was very good, but the evidence that this would accelerate or turn catastrophic was not good. RH: Can you just talk me through which bits of the mainstream climate story you agree with? The fact that the earth is warming, that humans are largely or predominantly responsible, talk me through that. MR: Yup. We are increasing carbon dioxide levels. We’ve increased them from 0.03% to 0.04% of the atmosphere. I don’t have any problem with that. I’m pretty sure it’s to do with industrial activities, possible that something natural’s going on but I think it’s highly unlikely.

Commented [8]: A 1C warming is very significant for the P Forster [8]: globe and it has occurred rapidly. Ridley does not like the original hockey stick graph. It is ok to be critical of this original graph, but the science was new at the time of its construction. The science has moved on since then and much-improved equivalent graphs show warming is unprecedented in at least 2000 years (see Fig 5.7 WG1 Chp5 p409). Commented G Schmidt [GS9]: [9]: This is just wishful thinking and confirmation bias at work. Given that the Pliocene was only about 3C warmer than pre-industrial, and sea level was ~20m higher, where does he think the temperature threshold is for the eventual collapse of the Greenland and West Antarctic ice sheets? Or does he not think that would be a problem? Commented [10]: Although correct, this plays down the P Forster [10]: role of carbon dioxide (CO2). 99.9% of the atmosphere is nitrogen and oxygen, which are not greenhouse gases. For a greenhouse gas, CO2 concentration is high, only exceeded by water vapour in the lower atmosphere.

That carbon dioxide is a greenhouse gas – yes, no problem with that. That carbon dioxide on its own would produce a degree of warming for a doubling of carbon dioxide – that’s basic physics, completely accept that. RH: Well you say that, but there were some sceptics, you wouldn’t put yourself in this camp presumably, who have resisted each one of those facts along the way and slowly, slowly moved along? MR: There are certainly some sceptics who’ve resisted those facts all along, but I’m

Commented [11]: Not clear what "on its own" means. P Forster [11]: Assuming the Earth responds as a physical black body, a doubling of CO2 would lead to 1.1 or 1.2C of warming - this is probably what he refers to. However, the Earth does not respond as a black body: the Earth responds to amplify this initial warming. In particular, atmospheric water vapour, the most important greenhouse gas increases and adds to the warming. Overall, the warming is higher and the IPCC estimates this warming as the Equilibrium Climate Sensitivity (ECS). Ridley’s number is lower than the ECS estimated by IPCC. The IPCC AR5 likely range for ECS is 1.5 to 4.5C (WG1 SPM p14).

not convinced that there are some who started out resisting those facts and gradually accepted them, there might be some. RH: So you – MR: So the people, for example, who think that the warming we’ve seen is all to do with the sun, I don’t think some of those have come over to the view that it’s partly man made. RH: And you don’t agree with that, so what is your position now? You call yourself now a lukewarmer, what exactly does that mean? MR: That means that the Intergovernmental Panel on Climate Change has a forecast that we’re going to see between 1.5 and 4.5 degrees of warming over the next century, roughly speaking, and I’m at the bottom end of that range. I’m probably within that range. I think we probably will see 1.5 degrees of warming – this is above preindustrial levels, so some of it’s happened already so essentially the full carbon

P Forster [12]: Commented [12]: This is not true. Ridley is confusing equilibrium climate sensitivity (ECS), the temperature change you get for a doubling of carbon dioxide, with the warming projection out to 2100. In fact, the IPCC does not make a forecast for 2100 as it depends on societal choices. If we continue to burn fossil fuels as we are, IPCC shows projections could go well beyond 4.5C. If we cut emissions to zero before 2050, we might just keep within 2C.

dioxide warming effect could happen, but what I think is very unlikely to happen, because there’s all sorts of lines of evidence suggesting this doesn’t seem to be likely, is the feedback amplification, mainly through water vapour, that the models have been assuming, and that this is why the models have been consistently overpredicting warming, as conceded by the IPCC in its latest report, where it admitted that 114 of the 117 model runs it looked at were too high, too warm. And if you go back to the 1990 report, the first IPCC report, they said, ‘We expect 0.3 degrees per decade, and they didn’t say starting in 30 years, they said, ‘starting now’. And we haven’t seen anything like that. RH: No, that was clearly wrong. They had clearly underestimated the medium-term

Commented [13]: This again is a confused argument. P Forster [13]: Ridley is making arguments about ECS, and implying they pertain to 2100 warming. In fact, ECS has very little to do with the rate or final warming we will see at 2100. Commented [14]: This is not a direct quote. The IPCC’s P Forster [14]: First Assessment Report in 1990 said about 0.3C per decade, with a 0.2 to 0.5C range for one scenario. But it missed some important effects, such as aerosols. Later reports corrected this.

trends, the great sporadic ocean currents and the changing thereof. They were hubristic at that point I think we could agree. MR: Yes, and they continued to be so, because they’ve been consistently wrong ever since.

P Forster [15]: Commented [15]: Not clear what aspect Ridley is referring to here.

RH: But they are much more cautious now, but very confident still that we will see a serious degree of warming, over the 2° which is generally recognised to be an acceptable threshold of warming.

Carbon Brief [16]: The Cancun Agreements (11 Commented [CB16]: November 2010) committed governments to “hold the increase in global average temperature below 2C above preindustrial levels.”

MR: Well, I don’t agree there. I think they are much more cautious, you’re right, if you read the actual report as opposed to the Summary for Policy Makers, which is much more alarmist, then they are much more cautious. For example, they have a whole table where they knock out a lot of the tipping points. They say the halting of the Gulf Stream, the collapse of the Greenland icecap, the halting of the Indian Monsoon, these are very unlikely. Now these were possibilities in previous reports that were taken quite seriously. Now they’re saying that’s not going to happen. They’re also saying – RH: No, they’re not. They’re saying the high impact, low probability event; I’ve just got to pick you up on that because – MR: No, they’re saying we have very high confidence that these won’t happen. RH: That’s not quite the same as saying it’s not going to happen.

Commented [17]: IPCC never said that these events P Forster [17]: were likely.

Commented [18]: The tipping point evidence is quite P Forster [18]: nuanced, in fact. Some events are high impact but low risk. Others are higher risk but not as dangerous. We have high confidence in some assessments (e.g. West Antarctic ice sheet collapse being unlikely) but very low confidence in others (e.g. methane release from the Arctic being relatively likely). See for yourself in Table 12.4 of AR5 Chapter 12 (p1115). Commented Chris Hope[CH19]: [19]: Indeed, see also Hope & Schaefer (2015) “Economic impacts of carbon dioxide and methane released from thawing permafrost” Nature Climate Change.

MR: No, OK, fair point. 99% rather than –you know they have specific figures for what they mean by this and 99% not 100% of course, but yes, they have definitely downgraded the possibility of these alarming tipping points. The methane burp from the Arctic is one of them, etc. RH: There’s still a lot of uncertainties about that, you would agree? MR: There’s a lot of uncertainties about everything, yes. RH: There are indeed. Which makes me, as an interviewer, slightly worried when I hear people, from whatever side of the debate they’re on, being too categoric about what we’re going to get. MR: Absolutely! And yet I have to listen, all the time, to politicians and journalists telling me that I am in denial for saying we may well not get dangerous warming. RH: Well I’m not one of those journalists. Let me quote at you a piece of – MR: No, it’s alright. I’m not picking on you, I’m just talking about the position. RH: Let me quote something from one of your articles. You said, ‘A cumulative change of less than 2 Celsius by the end of the century will do no net harm. It will actually do net good. Rainfall will increase slightly, growing seasons will lengthen, Greenland’s icecap will melt only very slowly’ and so on. I’m just wondering, in terms of confidence of assertions, what do you base those on? Like the 2 Celsius by the end of the century will do no net harm and will actually do net good; what’s that based on?

Carbon Brief [20]: ‘Cooling Down the Fears of Climate Commented [CB20]: Change’ – Matt Ridley - The Wall Street Journal, 18 Dec 2012. Commented [AH21]: Andy Haines [21]: The original meta-analysis on which this statement is based [Tol 2009] cannot reliably tell us whether there would be no net harm from a cumulative change of up to 2 degrees C because it omits many indirect effects of climate change. In the abstract of the paper, Richard Tol says: "Current estimates of the damage costs of climate change are incomplete, with positive and negative biases. Most important among the missing impacts are the indirect effects of climate change on economic development; large scale biodiversity loss; low probability, high impact scenarios; the impact of climate change on violent conflict; and the impacts of climate change beyond 2100."

[Cont…]

MR: That’s based on the peer reviewed literature in economics, which is very clearly pointing to net benefits up to around 2°. Now it’s not very precise, nobody’s sure that at 2° it turns negative, but the point is most people think 2° is when it turns catastrophic. That’s not right. The literature is very clear; 2° is when we start to get

Commented [22]: This is based on one world view which R Betts [22]: holds that "harm" and "benefit" can be quantified entirely with economics. Another world view would hold that impacts on biodiversity and people's way of life have value in ways which go beyond just money.

harm. Up until then we get benefit. Now it might be wrong, we might see benefit petering out sooner than that, but we know we’re getting benefit at the moment from carbon dioxide and from warming…

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Chris Hope [CH23]: [23]: We all need to be clear on Commented definitions here. If, as Tol suggests, we see some initial benefits from temperature rise, then at some point the initial benefits stop and we start seeing harm from the next tiny increment of temperature change, Tol thinks this will occur at 1.1C [Tol 2009]. But of course, we cannot be certain of this. What Ridley seems to be talking about is the point at which the harm from temperature rise exceeds the initial benefits. If you believe Tol's new figure, this could still not happen until the temperature has risen by 2C or so. But for policy purposes, it is the point at which we start to see harm from the next tiny incremental temperature change that matters. Tol thinks this is 1.1C, and we are pretty much at that point already. And we are certainly committed to go past it, even with no more emissions.

P Forster [24]: Commented [24]: This is not true. Even the most optimistic authors, e.g. Richard Tol, have net harmful effects beyond 1C - where we are today. [CB: See the transcript of an interview with Tol for Episode 1 of the BBC’s Changing Climate series. He is asked where the boundary lies between net positive and net negative impacts and gives the answer 1.1C]. Some parts of the planet have experienced harm for a long time - e.g. lowlying islands.

R Myneni [25]: Commented [RM25]: This is human-centric view. Polar bears, for example, are not seeing any benefit from the greenhouse climate that we are already experiencing. The billions of dollars in damage from intensified storms that we have already racked up in the past two decades is conveniently forgotten in the above argument.

…because for example winter deaths are more than summer deaths in most countries, even a country like Greece sees far more deaths in winter than summer. So slight warming, particularly in winter, because of course remember this warming is more in winter than in summer in the northern hemisphere, will produce a lower death rate, it will increase the amount of land available for crop use, it will probably increase rainfall slightly and it will fertilise the ecosystems of the planet.

Andy Haines [26]: Climate change is likely to have a Commented [AH26]: range of effects on health beyond the direct effects on cold and heat related deaths. The balance between decreased cold-related deaths and increased heatrelated deaths worldwide is uncertain. World Health Organisation (WHO) estimates suggests around 150,000 additional deaths per annum from climate change, for example from increases in under-nutrition, diarrhoeal diseases, malaria and flooding. There is also increasing evidence that increasing thermal stress will reduce labour productivity in tropical and sub-tropical regions. Indeed, increased migration of rural labourers to urban centres is already occurring in countries such as Pakistan a result of decreased ability to perform agricultural work due to thermal stress.

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Commented Sari Kovatz[SK27]: [27]: There is no evidence to support a statement that climate change will cause a "lower death rate" in temperate zone countries - which could be what Ridley is saying but its not very clear. This is a misunderstanding of how temperature-related mortality is estimated. The evidence relates to deaths attributable to cold (outdoor low temperatures) which are called cold-related deaths by the epidemiologists. It is correct that in most countries, even ones with hot summers, the absolute number of cold-related deaths is greater than heat-related deaths, for an average year (in some countries such as the UK, cold related deaths are a lot larger and a more significant public health problem). Climate change will reduce the cold related mortality rate (deaths attributable to cold divided by the total population). The number of cold related deaths will also reduce - but not by so much as the population is ageing- and old people are more susceptible to cold. Thus, the ageing population will offset some of this benefit of lower temperature exposures. Where these benefits have been estimated, e.g. for UK, the reduction in cold related deaths is greater than the increase in heat-related deaths. Environmental temperature is only one small factor- and there are many other more important factors reflect the death rate in a population, such as Greece. So implying that climate change will lower the death rate in Greece is a nonsense.

Now we know this, this was a thing based on multiple thousands of experiments, that if you add CO2 to the air, you increase the growth rate of plants. What’s changed in the last few years, and people are not picking up on, is that we’ve got the satellite data to prove that this is happening. Several different data sets, the Normalised Difference Vegetation Index is one of them, showing that we’ve got a greening occurring in all ecosystems on the planet, in the Amazon rainforest, in the Sahel semi-desert etc. etc.

[Cont on next page…]

R Myneni [28]: Commented [RM28]: This is an inaccurate statement. Nearly all the CO2 enrichment experiments show enhanced plant growth only in the first few years after which the plants acclimatise. The fertilisation effect disappears because other factors (mainly nutrients) become limiting.

Andy Haines [29]: Carbon dioxide fertilisation Commented [AH29]: depends on adequate water for irrigation. Even if crop yields are higher, they may be of lower nutritional quality. Using data from free-air enrichment experiments, for example, Myers et al. (2014) found significant reductions in zinc, iron and protein in grain crops like rice and wheat. They also found similar reductions in zinc and iron, but smaller reductions in protein, in legumes like soybeans and field peas. Commented [30]: This is heavily talked about in IPCC P Forster [30]: and the scientific literature, and has been known about for more than a decade. It is accounted for in our climate models. Although we don't fully understand the fertilisation effect, we cannot be certain it will continue as the world warms. Commented [31]: There is indeed some modelling R Allan [31]: evidence to suggest that rising CO2 has contributed to a greening of the Sahara since the 1980s, but this is more related to a northward shift in the rainy belt linked to rising CO2 concentrations and also a recovery from drought in the 1980s, which has been linked with aerosol particle pollution.

We’ve got greener vegetation as a result of CO2. Now some of it is explained by other things, agricultural fertiliser, more moisture and so on, but there is now no doubt that you can say that we’ve got about 11% more green vegetation on the planet than 30 years ago, much of which is down to the CO 2 fertilisation effect RH: I think it’s fair to say that that has not been sufficiently trumpeted, in the media in particular, the positive benefits of CO2, but when I saw that quote, I assumed you’d taken the 2 Celsius doing no net harm, actually doing net good, I assumed that you’d taken that from Richard Tol, who’s very prominent in this field, the economist. We spoke to him a few days ago and he said that he believes that things will start turning negative from 1.1 Celsius above pre-industrial, and we’re almost at that now. MR: Well, he may say that now. He was saying something different a while ago, but there are other studies out there, as you say there’s uncertainty here. Given the capacity of human beings to adapt, to be able to get the good out of something while not suffering the bad, because of the way they change their behaviour, it’s easily possible it might be higher than 2°. These are very inexact sciences.

[Cont…]

Commented R Allan [32]:[32]: I think this refers to this work? [Donohue et al., (2013) It's worth noting that without uptake of some of the CO2 emitted by human activities by vegetation the atmospheric concentrations would be even higher. These processes are included in sophisticated Earth system models used to make climate changes projections. Commented [RM33]: Much of this is based on my R Myneni [33]: (+colleagues) unpublished studies - the satellite data of the past 30+ years do show a “greener” vegetation over about 30% of the global vegetated land area and this translates to about 11-13% increase in gross carbon fixation by vegetation. Our analyses showed that about 42% of this greening can be attributed to climatic changes in temperature, precipitation and solar radiation and the rest to anthropogenic factors (CO2 fertilization, Nitrogen deposition, land use management history, etc.). This, Lord Ridley, does not mention, although they are contained in the same sources from which he falsely claims that CO2 fertilisation is responsible for the greening of the Earth.

R Betts [34]: Commented [34]: Yes, I largely blame the media here! And NGOs. CO2 effects are well known in climate science and included in climate models and many (but not all) studies of climate impacts on ecosystems and agriculture. But the media and other "climate communicators" cannot cope with nuance, so for them it always has to be one of the spectrum or the other which means that someone like Ridley gets to say that an issue has been ignored when it hasn't. And worse, he can only get it on the agenda by exaggerating.

RH: Well it rather depends where you live, doesn’t it, and how well developed your country is and rich you are or how poor you are, how susceptible you are to sea level rise, all those things, the distributional effects are massive, aren’t they? MR: Absolutely, and that of course is the key point, is that the reason the number of deaths in the world from droughts, floods and storms is 93% lower than it was in the 1920s is not because the climate’s got less dangerous in that time; droughts, floods and storms are probably just as common as they were then. It’s because people got richer, they got better sheltered, better transport, better communication, all these kind of things. So when a hurricane hits a really poor country like Burma, it kills far more people than when it hits a relatively wealthy country like India or Mexico. And so that’s what we need to be doing, to protect people against weather, whether it’s getting worse or not, we need to be helping them get richer, so that’s the crucial point

Commented [CB35]: Carbon Brief [35]: Carbon Brief has searched the academic literature for this 93% figure. It appears in a 2009 paper by Dr Indur Goklany, published in the official journal of the Association for American Physicians and Surgeons (AAPS). The group describes itself as “non-partisan” but is recognised in the US as a conservative political action group. On its website, the AAPS describes carbon dioxide as “the basic building block of all living things and also a weak greenhouse gas." The 93% figure also appears in materials published by the Global Warming Policy Foundation (GWPF) and the Heartland Institute, climate-skeptic lobby groups in the UK and the US. Dr Indur Goklany is a member of the GWPF’s advisory board.

is are we focussing on the wrong thing? Are we trying to stop some tiny increase in the probability of a hurricane hitting you, or are we trying to stop you dying when a hurricane does hit you? RH: And here you would make your argument for coal? MR: Well, no, I’m not making an argument specifically for coal. RH: You said earlier on you wanted to make an argument for coal. MR: Well the point about coal is that it has produced enormous improvement in human living standards, and not just coal, same with oil, same with gas, same with all three fossil fuels. The improvement that they have done to human life is spectacular, but not just to human life, to the planet as well. And people somehow think that fossil fuels are evil, but just look at what they’ve done! They’ve stopped us cutting down forests. If Britain hadn’t shifted to coal we’d have deforested this country very quickly.

P Forster [36]: Commented [36]: This is a very legitimate policy choice of what society does about extreme weather and climate change. To make this policy choice you need the best information from climate science. An argument against one policy choice over does not need to bring climate science into question. Andy Haines [37]: It’s obviously correct that we need Commented [AH37]: to reduce poverty as rapidly as possible. But climate change is likely to increase poverty, for example, through reduced labour productivity from increased thermal stress. This has already started to happen and, depending on emissions, [labour productivity] could decline to less than 40% by 2200 in peak months with tropical and subtropical regions experiencing extreme thermal stress. Commented [AH38]: Andy Haines [38]: This is not contested but does not mean that the use of fossil fuels will continue to do so in perpetuity. Commented [CB39]: Carbon Brief [39]: The World Health Organisation says that coal and other polluting fossil fuels now pose a “major burden on sustainable development.”

As it is we’re reforesting this country very rapidly at the moment. Oil has stopped us killing whales, whales and penguin populations plummeted. The advent of kerosene is what killed the US whaling industry in the nineteenth century. The whaling industry came back in the twentieth century, but again it went away because basically there’s no need to use animals for energy, which is what we were doing. The advent of gas had a spectacular effect on human living standards because it

Commented [AH40]: Andy Haines [40]: Right ...and now we need to replace fossil fuels with renewables! Renewables have a range of co-benefits for health including reduced air pollution.

enabled us to make cheap fertiliser, and cheap fertiliser has fed the world and basically we’ve got 9 billion people more easily fed today than 3 billion people in 1960.

Commented [AH41]: Andy Haines [41]: This is incorrect. The current world population is around 7.4 billion.

RH: All these points are extremely well made, but I’ve just come from an interview with Lord Stern, in which he says if we’re talking about coal for instance, if you priced in the externalities of coal, that’s the costs that are not taken up by the people who are burning the coal, costs on society, air pollution in particular he cites, local air pollution and also CO2 into the atmosphere causing warming, that the dis-benefits of coal vastly outweigh the benefits of coal according to his most recent analysis. MR: Yeah, well I think he’s completely wrong about that, because when you think about it, I’ve just mentioned the greening of the planet, I’ve just mentioned the failure to cut down the forests as a result of coal. These are benefits of coal, they’re also externalities, and the idea that local air pollution is a problem from coal, yes, it’s a

Commented Chris Hope[CH42]: [42]: CH: There are many peerreviewed studies of the possible climate dis-benefits of fossil fuels, such as Hope (2013) “Critical issues for the calculation of the social cost of CO2: why the estimates from PAGE09 are higher than those from PAGE2002.” To be convincing, Ridley needs to cite the peerreviewed studies that show these to be wrong. Commented [CB43]: Carbon Brief [43]: See comments [28]-[34].

problem when you burn unabated coal in a dirty way in cities, like in Peking today, but in this country we’ve largely got rid of that. We have extremely good controls on

Commented [CB44]: Carbon Brief [44]: Beijing in northern China was formerly known in English as Peking until the late 20 th century.

the sulphur emissions and the nitrogen emissions from coal burning, so actually we’ve adapted. We’ve got the benefits of coal without the dis-benefits. So it’s simply not true to say that the externalities of coal are negative; I think they’re positive. When you think about it, he’s saying that the CO2 externalities, the negative CO2 externalities in 2100 are more important than the positive CO2 externalities today. Well, I wonder if that’s fair? The people of 2100 are going to be much richer than today, they’re going to start to suffer marginal damage from climate change, not necessarily very great damage. How can we be sure that if we cut coal off today – and coal is by far the cheapest way of making electricity, there’s a billion people on

Commented [AH45]: Andy Haines [45]: Ridley quotes no evidence at all for his statement. It is correct to say that the levels of air pollution from coal can be reduced by emission controls. But even now, power plants are estimated to cause around 7500 deaths per annum in the USA. Coal fired power stations are the largest single source of mercury in the USA. Mercury is a potent neurotoxin. In the UK, estimates suggest that coal is responsible for 1,600 premature deaths, 68,000 additional days of medication and 363,266 working days lost. These health effects of coal cost £1.1 to 3.1 billion (€1.3 to 3.7 billion) each year in the UK.

the planet who have not got access to electricity, there’s 4 million people dying every year ‘cause they’re cooking over wood fires, because they don’t have access to coal. How can we be sure that we’re not doing those people a disservice if we stop burning coal now? RH: I’m not sure you’d want those people to be breathing in the coal fumes on a stove.

Commented [AH46]: Andy Haines [46]: Ridley is referring to the annual deaths from household air pollution (4.3 million), as estimated by the World Health Organisation in 2012. But they are not all due to burning wood - a variety of solid fuels are used (wood, animal dung, crop residues and coal). However, the energy required to provide clean household energy for the 2.7 billion or so people currently reliant on these solid fuels for household energy is actually quite small in comparison to global energy use.

MR: No, no, but you use the coal to make electricity, like we do in this country, that’s the point. RH: Yes. Assuming you can get it to those people. MR: Exactly, but that’s the cheapest way of getting it. If you do it from wind power it costs roughly three times as much. RH: Well it is at the moment, but one of the things that you have disparaged in your columns is subsidies, so subsidies for solar for instance; yet subsidies for solar have brought the cost of solar panels plummeting by 70% in the past few years, so solar now, not wind but solar is the real competitor to coal in developing countries, particularly in sunny areas, and we could easily see, in the next ten years I think we’re going to reasonably anticipate seeing that solar would become the best option in sunny countries.

Commented [47]: This is not correct. Whilst figures on J Watson [47]: the economics of coal generation are rarely published these days (the usual comparator is new gas), the difference between wind and coal costs is likely to be closing fast - especially if carbon costs of coal and any intermittency costs of wind/solar are included in their respective costs.

MR: It’s still about three times as much as the cost of coal, because remember although the cost of solar panels has come down, the cost of the whole transmission system with wires and land and all these kind of things is still huge. RH: But if you’re going to build it on a local village basis or a regional basis or a micro-grid basis – MR: I’m sorry, the numbers just don’t support that, Roger. It really is clear. For a start … I mean I’m all for solar, I love solar, and particularly in sunny countries, fine, let’s do it as much as we can, but the idea that we should pour ten times as much subsidy per unit of energy into solar as put into fossil fuels, I’m not sure that’s right, given what fossil fuels we know can do for poor people in the world. Do you know what the percentage of the world’s primary energy that comes from solar power today, to the nearest whole number, is? RH: Tiny.

J Watson [48]: Commented [48]: 'Huge' is an overstatement - the Committee on Climate Change said that, on average, the costs of intermittency for a 2030 decarbonised electricity system are roughly £10/MWh. That is only an eighth of the costs of wind & solar electricity in the latest DECC auctions for contracts (both came in at around £80/MWh).

There is also a wider point - all technologies impose some costs on the system at some level. Balancing the system is a system wide issue, so the costs should be shared by all users of the electricity network. It would not be very economically sensible or fair to load all of those costs on to individual wind or solar generators. J Watson [49]: Commented [49]: This leads to some pretty arcane and semantic discussions about subsidies. There are many conflicting claims. Yes - direct production subsidies for some renewables/low carbon technologies are significant; so (arguably) are tax breaks for fossil fuel extraction and subsidies due to under-pricing the carbon emissions when they are burned. There was a good review done by Will Blyth for the Environmental Audit Committee a year or two ago.

MR: Zero. It hasn’t even got to half a percent yet. RH: It hasn’t, and that is an absolutely massive challenge, but it doesn’t necessarily mean we shouldn’t be investing in it, does it? And the other numbers you mentioned – MR: Investing, fine, yeah, but –

RH: The other numbers you mentioned on coal and the amount of public money going into coal, the World Bank and others have put out reports showing there is vastly more money going into subsidising fossil fuels than there is into renewables. MR: That’s misleading. First of all they are consumption subsidies not production subsidies, so they hit poor – RH: Well some are. There are both, aren’t there? MR: No. Nearly all of them are consumption subsidies. Very few of them, by the way, are in this country, they’re all in places like Iran and so on, so they are helping poor

Commented Chris Hope[CH50]: [50]: The World Bank and IMF work includes externalities from fossil fuel use, and they make up a large part of the subsidies. Commented [51]: That is true - about fossil subsidies J Watson [51]: worldwide being dominated by consumption subsidies. But this is not a 'free lunch'. As the IEA pointed out in its climate change report earlier this year, some countries spend significant proportions of their budgets on such subsidies. That is money that is not available for other things, including other measures that could help alleviate poverty etc. Commented [AH52]: See comments above (CB: A Haines [52]: Comment [45]) Much of the subsidies result from failing to take into account the externalities, which also affect the poor. Many subsidies disproportionately benefits middle and high income groups who tend to use more energy.

people, whereas we are doing production subsidies in renewable energy, which hit poor people harder and reward rich people. That’s uncontested. RH: But that would be – I mean you’re a politician as – MR: And secondly, there’s ten times as much subsidy for renewables as for fossil fuels per unit of energy they produce. RH: You’re a politician of course as well as a science writer, as well as a columnist. If you were worried, and if the parliament was worried about poor people being hit disproportionately, which they are, by renewable subsides, wouldn’t a rational thing

J Watson [53]: Commented [53]: This is not entirely true. Whilst many beneficiaries are middle class, there has been significant investment in solar by housing associations etc., many of which own housing in lower income communities. I don't know how important this is as a share of overall deployment. Commented [AH54]: Its unclear what this refers to. A Haines [54]: Does it take into account the externalities of fossil fuel and conversely the co-benefits of renewables? Fossilfuel subsidies can be a barrier to the development and uptake of renewable energy technologies. Many renewable energy technologies are immature and costs are falling rapidly whereas many fossil fuel technologies are mature.

to say well if tackling climate change is a public good, let’s pay for it from general taxation? Wouldn’t that be rational? MR: Yes indeed. I think that would be far fairer and more rational than subsidising these renewable boondoggles, which are resulting in huge rewards to land owners, huge rewards to rich investors, huge rewards to people who want to shelter from inheritance tax etc. People like me! I mean I could benefit enormously from wind. I’ve many times turned down offers from wind companies to build turbines on my land ‘cause I don’t like ‘em and I don’t think they’re right and I don’t think people like me should be getting those subsidies. RH: Is that something you would advocate for, a shift to general taxation for whatever

J Watson [55]: Commented [55]: History shows (see the work of Prof Carlotta Perez et al) that all big transitions tend to involve phases where some firms make excess profits. Ridley is right to be concerned about this, especially if public money is involved. But those who make that argument forget that those subsidies, if designed well, are doing a very useful thing - they are paying for technological innovation, learning and cost reduction. That cost reduction benefits future consumers.

renewables subsidies come out of the melting pot that they’re in at the moment? MR: No, I don’t think it should be renewables subsidies. A shift to general taxation for the cost of climate change, the cost of carbon measures. I just don’t think that cost is very great and I don’t think we should be pouring money into it.

Commented Chris Hope [CH56]: [56]: To be clear, this is a call for a carbon tax.

RH: You take a very optimistic stance on the effects of climate change, and pessimistic stance on the technological fixes to it. MR: No I don’t. I don’t take a pessimistic stance on the technological fixes to it, by no means. I think there are some spectacular technological fixes out there. Cheaper gas, nuclear power in many different forms, molten salt reactors, thorium reactors, small modular reactors. I think we’re going to see spectacular changes in our energy mix over the next few decades, which will result in us decarbonising pretty rapidly. I mean by far the biggest burst of decarbonisation came in the United States, where

Commented [57]: This is not a 'fix' - it can help reduce J Watson [57]: UK emissions for the next 10-15 years by replacing coal. But beyond that, significant gas use also requires Carbon Capture and Storage (CCS) to be used widely. That is looking less likely following the recent announcement that the UK demo programme would be cut.

they shifted from coal to gas as a source of electricity. We could have done that in this country. RH: Well we have done it already. We preceded the US in the shift to gas. MR: Well, we had a dash to gas and it ground to a halt. Why did it grind to a halt? Because nobody at the moment wants to build a CCGT, a combined cycle gas turbine, in this country, because the economics don’t add up because of wind on the grid. That’s what’s happening. RH: You made some interesting comments in the Lords the other day about obliging firms to pay for the disposal of their own CO2. Can you talk about that, explain your thinking on that?

J Watson [58]: Commented [58]: This isn't the only factor. The lack of gas investment over the last few years has been poor economics when compared to coal, and not just due to any fall in electricity prices due to renewable growth. Policy uncertainty has also played a big role, especially about the likely shape of the capacity market and whether or not there will be an emissions performance standard.

MR: Yes, there’s a suggestion in parliament at the moment that carbon capture and storage, which is a long shot technological solution to this, where we actually sequester the carbon and put it back in to help oil recovery and things like that … we’ve struggled to find ways to get this technology off the ground and to support it, and I don’t, myself, have huge hopes of it. I think it’s going to remain too expensive for a long time, it’s cheaper than offshore wind but that’s not saying much as a way of cutting carbon dioxide emissions, but at the moment we hit fossil fuels with very heavy taxes. I mean this thing called the Carbon Floor Price, which is a unilateral British decision on top of everything else, means that it’s hitting fossil fuels

Commented [59]: I'm not sure that's true. The UK J Watson [59]: government had a pretty good plan, which may or may not have worked. Similarly (and more important), firms in the US and Canada are building CCS plants. Yes, the technologies are uncertain (especially their costs) but that doesn't mean that there is a lack of knowledge about what is needed in terms of government policy and incentives.

very hard in this country, and that’s one of the reasons we’re seeing closures of coalfired power stations at the moment, which is putting our electricity grid at risk. RH: Well the main one is in terms of local air pollution as well, they’re coming to the

Commented [60]: Ridley is over-stating this. It is the J Watson [60]: unreliability of coal plants that led to the tight margin a few weeks ago.

end of their useful life ‘cause they can’t pass laws on air pollution. MR: Yes, but one of the reasons nobody’s building super-critical new coal-fired power stations is that would produce less CO2 per unit of energy and less pollution, is because there’s no future. Why? Because wind is dumped onto the grid whenever it’s available and that destroys the economics of new power plants in this area. So anyway, if we want to support CCS, better to do it by saying to the fossil fuel industry put aside some of your money to support CCS, particularly CCS R&D, research and development, into how to improve this technology, and then we’ll let you off some of these carbon floor price things. I think that’s a very sensible idea. It

Commented [AH61]: So it’s cheaper then? This seems A Haines [61]: to invalidate earlier arguments about wind being so expensive that it can’t compete.

J Watson [62]: Commented [62]: See my comment above (CB: Comment [58]). The other reason is that supercritical coal only gives you marginal gains when compared to the efficiency of existing coal plants.

might also help in the North Sea, where we’ve got a huge problem of decommissioning the oil industry and where if we could give it a new lease of life we’d save a lot of jobs. So I think that’s an imaginative suggestion that’s come forward in the House of Lords, and I was happy to support it. RH: It’s very elegant, isn’t it, because what it’s doing is turning CO 2 into a waste like any other waste, so if you’re a chemical firm you produce a chemical effluent that’s toxic, you need to get rid of it. It’s basically saying to fossil fuel firms, you produce the CO2, you need to take some responsibility for it, which is quite simple and I think might be appealing. MR: Yes, except that the problem with that way of thinking of it is that it equates CO2 with a pollutant, and it isn’t a pollutant. 95% of the CO2 in this room at the moment was not produced in industry; it was produced by natural processes in the natural environment. Only about 5% of CO2 released into the atmosphere every year comes from industry. It’s an enormously natural process for CO2 to be released into the air and absorbed. Now our activities have increased the amount of CO 2 in the air from as I say 0.03% to 0.04% and that has slightly increased the growth rate of crops, the growth rate of plants, the growth rate of deserts, the growth rate of tropical rain forests; that’s added something like $100 billion a year to the value of the world’s harvests, so shouldn’t farmers be paying coal companies compensation for the fertiliser they’ve been freely given by the coal companies. I’m not making that as a serious political suggestion, but why not, by the logic of what you just said? RH: You are being provocative again and in a lot of your columns you are provocative, you’re hired because you’re provocative. MR: Well, I try and tell the truth is what I do. RH: Yes, but also because you have a wonderful style, you’re an extremely smart guy and because you have a consistent line in provocation, which gets people worked up. One of your books, The Rational Optimist, a fine book, but by painting yourself as the rational optimist, don’t you always predetermine your line of enquiry into anything? If you, ‘Oh, I’m going into this as a rational optimist’ it frames your view, doesn’t it?

Commented [AH63]: Andy Haines [63]: There is evidence that CO2 may not be inert - see earlier points about nutritional implications of CO2 fertilisation [Comment 29] and recent work suggesting that CO2 levels in buildings may cause adverse cognitive effects at much lower levels than were previously thought to be problematic.

Chris Hope[CH64]: [64]: It only 'isn't a pollutant' if you Commented dismiss the whole peer-reviewed literature on the likely damage from climate change. P Forster [65]: Commented [65]: Ridley is confusing emissions with concentration. Concentration-wise it would be over 2/3 natural and 1/3 man-made. Commented [CB66]: Carbon Brief [66]: See comment [10].

Carbon Brief [67]: See comments [28]-[34]. Commented [CB67]:

MR: Well, no, because actually when I set out to write that book it was going to be a neutral book about progress, the pros and cons, literally, and the more I got into it the more I found there were no cons, or at least there were very few cons. I mean to take happiness for example, I thought it was true that the richer people got, the less happy they got. So this was a real drawback to economic growth. I discovered that the literature’s been turned on its head in recent years and actually that’s not true. There is a correlation within countries, between countries, within lifetimes, between wealth and happiness. RH: To an extent, and once you get very rich – MR: It’s a correlation, it’s a correlation. Oh, it’s possible to be very rich and very unhappy, but that’s alright ‘cause it cheers other people up.

Andy Haines [68]: Ridley is talking about within Commented [AH68]: country comparisons rather than between country comparisons that I think are being referred to in comment 69. Easterlin (2001) concludes “The material aspirations are initially fairly similar among income groups; consequently more income brings greater happiness. Over the life cycle, however, aspirations grow along with income, and undercut the favourable effect of income growth on happiness, although the cross sectional happiness-income difference persists.’ Chris Hope[CH69]: [69]: Layard's work on this finds a strong Commented correlation up to a per capita income of $15,000 per year, and almost no correlation at higher incomes.

RH: OK, so look, I mean it’s comments like – MR: My point is I arrived at my rational optimism by argument, not by attitude. And I particularly looked back at all the environmental doom and gloom I was told in the 1970s when I was a student, which left me really depressed about the future of the world, that the population explosion with unstoppable famine was inevitable, pesticides were going to cause a cancer epidemic, they were going to shorten my life, acid rain … nuclear winter, my sperm count was gonna fall, etc. etc. And these all turned out to be exaggerated. So am I supposed to say, when people come along and give me exaggerated claims about climate change, that aren’t supported in the proper literature, am I supposed to say, ‘Oh well, this time you’re probably right?’ No, I think I’m supposed to say, ‘Well hang on, I don’t think the evidence is as strong as that. I think the evidence for some man-made climate change is good; the evidence that it’s going to turn very harmful in anything other than the next century, by which time we’ll probably have cut our carbon emissions, I don’t see that evidence.’ RH: I mean some of those scares that you mentioned haven’t materialised precisely because we took action to stop them. So acid rain, for instance, we fitted scrubbers on our power stations…. MR: Actually that’s not my critique of acid rain, that it was a problem but we solved it. Go back and look. The evidence is now really clear, the biomass of European forests

P Forster [70]: Commented [70]: Evidence, or lack of it, needs to be evaluated on a case by case basis - IPCC WG2 does this across many cases and finds stronger evidence of harm than benefits.

was increasing in the 1980s. It really was. The forest death problem caused by acid rain was a complete myth. The biggest and best studies in the United States, in Canada, in Europe, came to that conclusion. RH: Let me ask you finally a sort of attitudinal question, which is what your critics raise with you, which is one of risk, you’re proposing that the world should say, ‘OK, we’re going to ignore these risks.’ Your critics point to the fact that you were Chairman of Northern Rock when it suffered a dreadful bank run, the first since the nineteenth century, and so they ask, should we trust you on risk, as a politician, as an advisor, as an influencer, a massive influencer, should we trust you on risk? MR: Well the thing that Northern Rock taught me, above all else, was not to trust groupthink. Because it was groupthink that we had a great business model, the FSA said that, the Bank of England said that, the City said that. There were one or two people who said, ‘Hang on – that business model is too good to be true,’ but actually they were saying that for the wrong reasons. There was no one who foresaw what was going to happen to us. RH: Well the Treasury Select Committee said you had a reckless business model, the board. MR: In retrospect, that was in retrospect. That was the point. But the Treasury Select Committee failed to learn the crucial lesson from us, even though they spent three hours grilling me and others, and that is that this could happen to any mortgage banks, and so other mortgage banks expanded their business after what happened to us, and a year later exactly the same thing happened to them. By then of course, the Bank of England had learned how to cope with it over a weekend rather than let it turn into a run on the high street, but that’s a different story. My point is that I learnt from the Northern Rock crisis that just because everybody says something, doesn’t mean you should believe it. And that’s whether they’re saying you’re risk free or whether you’re saying you’re risky. Think for yourself, that’s the conclusion. RH: Of course, and you do. But – as an evolutionary biologist, you are massively more influential than any individual climate scientist that I can think of, with your columns, your quite evident influence on Rupert Murdoch, your place in the Lords. It

would be slightly unusual for somebody, a climate scientist, to come into your area of evolutionary biology and attain such a degree of prominence. MR: But hang on, Roger – RH: Not unprecedented, but unusual. MR: I’m not an evolutionary biologist. I gave that up in 1983 when I finished my PhD. I’ve written books about it since then, I’ve got another one coming out shortly, The Evolution of Everything. RH: What would you describe yourself as? MR: I would describe myself as a commentator on science. I’ve been a science journalist since 1983, on and off. There have been times when I’ve been full time, there have been times when I’ve been freelance, times when I’ve been doing other things, and I’ve been a commentator on the climate debate since 1987. Well that’s actually 26 years. So when people say I’ve just breezed in and expressed some opinions on this, no. And I think it’s vital that we don’t pull credentialism here and say, ‘No one’s allowed to comment on anything.’ I get really furious flack for even suggesting that I have a view on climate science and climate policy, but it affects me as much as anyone else. I’m a citizen, aren’t I? I’m allowed to express my view and I feel that the world is making a historic mistake in taking this issue too seriously, and as a result neglecting some much more important environmental problems. I mean invasive species are what are causing extinctions all around the world, habitat loss is still a problem. If you look what’s happening to coral reefs, they’re being devastated, but not by climate change, not by ocean acidification; by runoff and overfishing and all these other different things. RH: I’m glad you mentioned that because I’m interested in ocean acidification, I’ve done some work on it, and as part of a mini documentary I was making last year I thought, ‘I really want to test this’ and I read one of your articles saying, ‘Actually I’ve just read this paper on ocean acidification written by Terry Hughes in Australia and it shows that the amount of coral will remain the same under an acidification scenario’ so I thought, ‘OK, I’m going to check this out.’ So I went with a BBC crew to Australia and interviewed this guy, and he said, ‘Yes, that is absolutely true. The amount of coral will remain exactly the same.’ And he went on to say, ‘But the branching corals

Hoegh-Guldberg [71]: This Commented [71]:

is a case of cherry-picking. Local factors are important but are not the whole story. Ocean warming has driven increasingly frequent and severe mass coral bleaching events with devastating impacts on the world's coral reefs. For example, in 1998, a cycle of heat stress across the world's coral reefs removed 16% of the world's corals. Many places have not recovered and we are facing another major event next year. Ridley elects to ignore the majority of the literature which was assessed during the latest IPCC (AR5 WG2 Chp30 p4). According to the vast majority of literature which is what the IPCC based it conclusions on: "Coral reefs within CBS, SES, and STG are rapidly declining as a result of local stressors (i.e. coastal pollution, overexploitation) and climate change (high confidence). Elevated sea temperatures drive impacts such as mass coral bleaching and mortality (very high confidence), with an analysis of the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble projecting the loss of coral reefs from most sites globally by 2050 under mid to high rates of ocean warming (very likely). {29.3.1.2, 30.5.3-4, 30.5.6; Figure 30-10; Box CC-CR}" Elsewhere In the executive summary: "Global warming will result in more frequent extreme events and greater associated risks to ocean ecosystems (high confidence). In some cases (e.g., mass coral bleaching and mortality), projected increases will eliminate ecosystems, and increase risks and vulnerabilities to coastal livelihoods and food security (e.g., CBS in Southeast Asia; SES, CBS, and STG in the Indo-Pacific) (medium to high confidence).”

Commented [72]: This is incorrect and ignores tens of Gattuso [72]: papers about coral bleaching. It is correct that overfishing and the input of dissolved and particulate matter from land are important local stressors. There is however considerable evidence that ocean warming is the major cause of coral bleaching and has already led to the demise of a large number of reefs. Also, the 50% decrease in coral cover in the best protected areas of the Great Barrier Reef clearly demonstrate that local factors do not explain the global demise of coral reefs. These are observations, not model-based projections.

and the fan corals,’ the sort of things that provide the habitat for all the tropical fisheries that we so love with coral reefs, ‘they will all disappear.’ He hadn’t mentioned that in his paper, because that’s not what the paper was addressing, it was addressing mass, it wasn’t addressing diversity. MR: So I did accurately report his paper.

Hoegh-Guldberg [73]: Commented [73]:

But cherry-picked the literature.

RH: You did accurately report it, but his paper didn’t mention the crucial bit, which is the things that make coral reefs special will disappear… MR: I think it’s very unlikely, because I’ve been reading a much wider ocean acidification literature, I don’t remember which paper that was, but I read papers since then, I’ve read other papers and in particular I read a meta-analysis, and I think the article you’re referring to particularly placed emphasis on a meta-analysis. Now a meta-analysis is an analysis of different studies, and this looked at 327 different studies of ocean acidification covering 45 different species, and came to the conclusion that this was not going to be such a big problem as the literature was assuming, and said there is very little evidence that we’re going to see huge and damaging changes from ocean acidification in the next century, there are several

Commented [74]: Very few of the almost 600 papers on Gattuso [74]: the biological response to ocean acidification are not based on field observations and experiments.

reasons for this. One is that the variation we’re talking about is very small, it’s from a pH of about 8.2 to about 7.9 during this century. RH: But faster than we’ve seen for many millions of years.

Hoegh-Guldberg [75]: What Commented [75]:

Ridley forgets to tell you is that the pH scale is exponential. That is, that a change of 0.1 pH units is equivalent to a 30% increase in the proton concentration or overall acidity!

MR: Hang on, hang on. But that is less than the variation between days at the intake of the Monterrey Aquarium. That is much less than the variation between different parts of the Pacific Ocean, between parts of coral reefs at different times of the day, so many organisms are already experiencing over matters of hours and days, the sort of changes that we’re talking about over decades, right? And if you go and look at the actual studies, there’s a recent study of a coral in the Caribbean which deliberately put the CO2 pressure over the tank up to certain levels so as to mimic what happened, and they got an increase in the rate of growth of this coral during the as it were 21st century. Eventually, when they got to 2500 parts per million, it started to drop. So what they said was it is unlikely that that sort of level of CO 2 is going to do any harm.

Again, Ridley is cherry picking. It is also confusing day-to-day variability with a shift in mean conditions. Yes, coral reefs go through variability in pH and carbonate chemistry, just like they do with respect to temperature. However, it is the extreme conditions and the average conditions which one experiences that are important. One is only to look at the paper by Dove et al (2014) to see what happens when you change the average conditions while still maintaining the variability. These sort experiments are very hard to argue against. Naturally, Ridley doesn't mention them. He needs to read and explain the results of studies like these ones which he has so carefully not mentioned.

Hoegh-Guldberg [76]: Commented [76]:

Hoegh-Guldberg [77]: Note: Commented [77]:

The Dove et al. (2014) paper and other ones like it show that you can have all the variability you want in the system, but if average conditions change, you get the loss of coral reefs. Ridley’s comments here are pretty baseless compared to the majority of the literature - again, as summarised by the IPCC.

RH: There was another paper saying that research typically didn’t factor in acidification with warming, and therefore the results would be much worse, but let’s not get stuck on the details of that, because I want to ask you a final question, this is a question we’re asking all our interviewees, I think I know the answer already, it’s what level of optimism have you got over this issue? MR: Well, I’ve got great optimism we will not see devastating climate change or extreme weather within our lifetime, within our children’s lifetime, within our grandchildren’s lifetime. However, I have got some pessimism that the measures we are taking today will do more harm than good, and that for example rushing into biofuels all around the world, putting 5% of the world’s grain crop into cars rather than people’s tummies, has probably killed 200,000 people a year. And I think that’s a pity. RH: You could be optimistic that we’d seen the end of those policies, which people would say were knee jerk policies.

Carbon Brief [CB78]: [78]: Commented This 200,000 figure appears in a press release by the Association for American Physicians and Surgeons (AAPS), which is based on a paper by Dr Indur Goklany published in the group’s official journal. See comment [35] above for more on the AAPS, Goklany and his association with the Global Warming Policy Foundation, a climate-skeptic lobby group on whose advisory board Ridley also sits.

MR: But we haven’t seen the end of those policies. They’re still going on. We’re still diverting 5% of the world’s grain crop into motorcars. Now it’s true that the price spike that they caused is over, agricultural prices have dropped. The reason for that is because we’re no longer putting more into motorcars, so the increase in yields that we’re seeing all around the world, partly as a result of the CO2 fertilisation effect and partly because of other technologies, the increase in yield is now able to feed the world easily, even while we feed a twentieth of the world’s grain crop to motor cars. RH: I just want to ask you one last thing. You’ve changed your mind in the past about climate change you’ve moved from one position to another. What would it take to move you back again?

Commented [RM79]: The fact that we are able to feed R Myneni [79]: the growing population has more to do with nutrient (chemical) fertilizer application, irrigation, productive breeds of crop varieties, etc. rather than CO2 fertilization. I know of no study that argued CO2 fertilization as the dominant reason for human food security!

MR: Very rapid temperatures rise. If we see, over the next ten years, half a degree of temperature increase globally – RH: But nobody’s forecasting that. MR: Indeed, but they were. I mean, at the moment I’m concerned I’m too much of a lukewarmer and I’m not enough of a sceptic… the deceleration of climate change over the last few years, it’s ticking up this year, but we’re making a big deal of it.

Commented Chris Hope [CH80]: [80]: No-one should make a big deal out of one year's climate. The problem is that sceptics and lukewarmers have been making a big deal of the one exceptional year of 1998 ever since; 'no temperature rise for 16 years' and so on.

RH: The surface temperatures, the ocean is still warming, ice is still melting. MR: Yeah, but the lower troposphere, which is where the theory says we should be seeing the warming, is warming least of all! That’s the bit we should be seeing warming, and that’s warming least. RH: So you want to be more sceptical rather than less? MR: Well I don’t want to be, I fear that I should have been. RH: Matt Ridley, thank you very much.

[Carbon Brief Note: The timestamps on the comments are not representative of when the remarks were made.]

Commented [81]: This is out-dated science when P Forster [81]: satellite data was not corrected for known biases. These biases have been corrected. Chapter 2 of AR5, Fig 2.24 and 2.26/7 shows that the troposphere is warming perfectly consistently with the surface.