My reply to

the climate change

sceptics

Kris Anderson

My piece (9 February) argues that not all opinions are equal, and that expert consensus should be respected as such. That point seems to have gone unheard by John Cameron and Edgar Lloyd. I'd like to refer them both back to my original article and later response to David Mackenzie and leave the matter there, as all three letters hint at an anti-establishment cynicism that leaves little scope for factual debate. However, their letters contain errors that demand correction for the benefit of other readers.
     For one, global warming is not a theory – it is a fact. The earth is getting warmer, and it's getting warmer with a speed that is unprecedented throughout geological record. It has been this warm – and CO2 levels have been this high – before (about 55 million years ago), but the earth has never warmed so rapidly before. So today's global warming is fact: this is measurable and proven.
     It needs, however, a theory to explain why it's happening now. The IPCC (which no scientific body of national or international standing has dissented against) has concluded that it is 90% certain ('very likely' – a statistically precise term) that this change results from anthropogenic (man-made) emissions of greenhouse gasses. It is not 100% certain because there are other theories out there (no one is denying that) – but those other theories do not explain the data as well which is why the IPCC says the anthropogenic theory is 'very likely' correct.
     International policies of mitigation, therefore, are founded upon a gamble: that if you've got a 90% chance of something disastrous being caused by something you can regulate, you'd be an idiot to count on that 10% chance that it doesn't need regulation. And even if you persist in believing that 10% chance that climate change is non-anthropogenic, global warming is still happening and we still need to be preparing for huge climactic disruption, man-made or not.
     This was a shared misunderstanding in both letters. But beyond clarifying the above and observing that both letters were very short on scientific specificity and long on speculation, I'd like to address some of their mistakes point by point.|
     Accordingly, in response to John Cameron's letter:
     • Al Gore is a politician and speaks the language of politics. He is not a climate scientist, and therefore does not speak the language of scientific probability. Of course all scientists are not agreed…but most are, and scientific consensus takes into account dissenting voices as well as those in accordance. I'll return to this point in a moment.
     • Even if 1,000+ scientists (source, please?) have challenged the IPCC report, that's not very many. While there are independent voices of dissent, no internationally-recognised scientific organisations have come out against the report. Moreover, many of those individuals who have challenged it are not climate scientists; many more have special agendas of their own (eg some petroleum geologists).
     • Dr Cameron commends Richard Lindzen as an eminent challenger of the IPCC reports. He neglects to mention that Lindzen authored Chapter 7 of the 2001 IPCC Report. Clearly Lindzen is regarded as a world-class atmospheric scientist, which is why he was a key contributor to the IPCC's findings. Which brings me back to point number one: true scientific consensus incorporates dissenting voices rather than marginalising them.
     • Dr Cameron says 'getting scientists to agree is like getting economists to agree: it's like herding cats'. That's a false analogy, and a lazy one. Economics is not a hard science: it's a social science, which means its high degree of complexity and variability allows for the irrationality of human beings. Climate change theories, on the other hand, are founded upon hard science. Also, the IPCC report is based on scientific agreement, as indeed is 'science' as a whole body of knowledge. Agreement, incidentally, does not imply conspiracy (as the term 'Climategate' suggests): we'd still be in the dark ages if it did.
     • Let's talk about 'Climategate'. Lord Oxburgh, fellow of the Royal Society, chaired an independent panel to assess UAE's so-called 'Climategate' scientists, whose emails have been used as the cornerstone of vast conspiracy theories from climate-change denialists. His committee concluded, 'We saw no evidence of any deliberate scientific malpractice in any of the work of the climatic research unit and had it been there we believe that it is likely that we would have detected it.'
     Independent reviews by the Muir Russell group and the parliamentary committee on science and technology's independent review concluded similarly. I'd recommend reading these before assuming that the UEA incident is proof that the world's scientists are all working together (like herding cats!) in some vast wool-pulling plot. (www.cce-review.org, www.uea.ac.uk, www.publications.parliament.uk)
     • The UN is an imperfect organisation, but accusations of 'fraud' need to be backed up with hard fact. Otherwise such language is just rabble-rousing.
     • Regarding computer simulations and acknowledgement of uncertainty: the IPCC's findings are based primarily on observational data – the computer 'simulations' mostly come at the mitigation stage, when trying to model the effects that climate change might have in the future. And the IPCC report, as its readers know, repeatedly, relentlessly asserts a 'clear statement of uncertainty' – that's what 'very likely' means.
     • Dr Cameron claims, 'the public has no idea how flimsy and circumstantial is their [who "they" are is unspecified, but I'm assuming it's climate scientists writ large] evidence.' No? Enlighten us, preferably using several peer-reviewed sources.
      • Our inability to predict with certainty (although there are certainly 'very likely' scenarios, eg sea-level rise and desertification) how climate change will affect us in the future has nothing to do with whether or not global warming is actually happening – which, again, is fact. Any implication to the contrary is founded upon false logic.
     • Finally, Dr Cameron writes dismissively about the 'logical nonsense' upon which the entire discipline of statistics is founded, claiming: 'If no single extreme event in an ensemble is due to global warming then when taken together they cannot be taken as evidence for the contrary'. But his logic is wrong and bizarre. First, a datum (here, a single extreme weather event) is never proof of a trend: that would be impossible. But when you have a full set of data, and a trend becomes visible, further data that fit the trend serve to support it. If there is a strong statistical correlation between the warmth of the ocean and the strength of hurricanes, we can't say that global warming caused Hurricane Katrina specifically but we can predict that global warming is likely to lead to stronger hurricanes. Incidentally, the word 'trend' allows that there is no model that will fit all the data – there will be data that lies outside of it (and thus probably dissenting opinions). Which is to say that all of the above, unlike Dr Cameron's opinions, allow for uncertainty. Mr Lloyd's letter was more considered and contained many understandable mistakes, most of which have been corrected in points above. But there are just a few points that deserve comment:
     • If widespread agreement (even if followed by a failure of policy-based action) always implies conspiracy and 'witch-hunts', then nothing I say will change Mr Lloyd's mind.
     • Mr Lloyd mentions that Al Gore et al use climate change as an excuse to burden us with taxes and landscape eyesores. If Gore et al had actually had their way, greenhouse gas emitting industries would be more heavily taxed (which, yes, might filter down to petrol prices, etc) but low-carbon energies would become heavily subsidised and would represent long-term savings to the everyman. Either way, Gore's 'green economy' hasn't been enacted, and as it stands, we'll be taxed very heavily indeed in the future so that the government can scramble to adapt to climactic changes that 'green taxes' at an earlier stage might have ameliorated.
     • For what it's worth, I like wind farms – and yes, I've lived near them.
     • Re: Claude Allegre, I could speak at length about just how unscientific the man is, but I'd rather let Georg Hoffman (a practicing climate researcher rather than a public pundit like Allégre) do it better. His article contains useful reference links, too: www.realclimate.org.
     • Re: Delort's and Dansgaard's work: as noted above, no one's saying that climate doesn't fluctuate. Palm trees once grew in Piccadilly; the Sahara was once marshland. But the current rapid rises in both global (not regional or backyard) average terrestrial and ocean surface temperatures are unprecedented, as is the rate of change and level of greenhouse gases in the atmosphere. True, there are other climate drivers, including changes in the earth's orbit (which bring us into and out of ice ages), changes in solar activity, and volcanic events. But none of these can account for what is being observed in terms of rapid global temperature increase unless manmade emissions are taken into account. Hence the widespread acceptance of the IPCC findings.
     • Cows fart methane, not CO2.
      I'm afraid that after this response, I'm laying the issue to bed, not least because others are far better qualified to speak about this. Please direct further questions to the IPCC, the Royal Society, the Royal Meteorological Society, the World Meteorological Organisation, the European Academy of Sciences and Arts, or other expert organisations. Or read up on it yourselves from peer-reviewed sources, and cast your net wide.

Kris Anderson is a lecturer in English literature for the Open University and a tutor in English at Oxford University. She is last year's UK and Ireland Young Thinker of the Year, an annual competition with which the Scottish Review is associated.