For years I’ve been writing about climate change – only to be told I’m a “climate change denier”. On Twitter, I’m criticised daily for “stupidity and ignorance”, told that I ignore the science, asked how I as a non-specialist can challenge “the global consensus of scientists” – though that consensus does not actually exist, and as Michael (Jurassic Park) Crichton put it, “If it’s science, it’s not consensus, and if it’s consensus, it’s not science”.
Yet in fact it’s the trolls on Twitter who themselves seem supremely ignorant about the science. Take an example. Everyone concerned with climate science, whether alarmist or realist, knows perfectly well that the (admitted) warming effect of CO2 is negative logarithmic – a law of diminishing returns. The more CO2 we have in the atmosphere, the less difference any given increase makes. In fact if doubling CO2 from (say) 200 ppm to 400 ppm causes a temperature rise of x degrees, then you need another doubling – an extra 400 ppm, not another 200 – to get another increase of x degrees.
When I mentioned this in a blog, there were howls of anguish from the “pro-science” Warmists, demanding evidence and peer-reviewed papers to justify such an heretical suggestion. I didn’t bother to reply – if they’re so totally ignorant of the subject, they’re simply not worth debating with.
The irony is that at least we ought to be able say what “x” is – how much warming do you get for a doubling of CO2? But even the IPCC doesn’t pretend to know. They give an estimated range of between 1.5oC and 4.5oC. That’s a huge level of uncertainty, and makes a nonsense of the political debate about “keeping climate change below 2oC”. Indeed some scientists believe that if you add in the effect of various feed-backs in our climate system, the figure could be close to zero, or even negative. Certainly the fact that real, measured global temperatures persistently and substantially under-shoot the forecasts of the climate models suggests that the real value of “x”, as mediated by feed-backs in the climate system, may well be lower than the IPCC estimate.
Another example of ignorance: many warmists seem to imagine (if they’ve thought about it at all) that global temperatures (and perhaps atmospheric CO2 levels) have been more or less constant since the dawn of time. They love to talk about the “pre-Industrial period” as though it implied stasis for millions of years. But as the graph above illustrates, global temperatures have been cyclical throughout the last 10,000 years, on a very roughly 1000-year cycle. Nothing in the graph indicates that anything unusual is happening. We merely seem to be moving into a new, cyclical 21st Century optimum. And by the way it’s called “an optimum” because on the whole human societies tend to do better and prosper more in warm periods than in cold periods (think Dark Ages).
And over the very long-term, on a geo-historical scale, we see that atmospheric CO2 levels have been much higher for most of the earth’s history than they are today (with no “runaway global warming”). We live in an atmosphere which is impoverished in CO2 terms. Indeed the “pre-industrial level’ of around 250 ppm was approaching the level which would threaten plant growth and undermine the viability of life on the planet.
But at least (say the warmists), we have our peer-reviewed science, and the “deniers” have no peer-reviewed science. Here, of course, they are profoundly mistaken. Try this book, published by the Heartland Institute and co-authored by my good friend Professor Fred Singer – an atmospheric physicist with a hugely imposing CV. The book references hundreds of peer-reviewed papers. Indeed some of the papers are the self-same ones cited by the IPCC, but are used here to support rather different conclusions.
The fact is that a significant minority of highly qualified scientists in the field are sceptical of the IPCC position. The debate is not about science versus ignorance,. It’s about alternative interpretations of huge, complex and sometimes contradictory data sets, and about a chaotic and complex climate system which despite all the peer-reviewed papers is still not well understood.