Matt Ridley: A Response To My Critics On Global Warming
My Spectator cover story on the net benefits of climate change sparked a lot of interest. There was an explosion of fury from all the predictable places. Yet not one of my critics managed to disprove my central assertion, that climate change is probably causing net benefits now and is likely to continue doing so for some decades yet.
I’ve written responses to some of the critical articles and reproduce them here.
1. Duncan Geere in the New Statesman.
Four paragraphs in his piece in turn begin with “He’s right…” so I am glad that Geere confirms that I am right about all my main points. If you read my article you will find that each of Geere’s assertions about the eventual harm of climate change are also in my piece. For example, I say:
“Even if climate change does produce slightly more welfare for the next 70 years, why take the risk that it will do great harm thereafter?”.
I do not ignore sea level rise: and anyway it is taken into account in all of the studies collated by Tol.
Geere’s main point, that the graph of benefits starts declining at 1C above (today’s) is very misleading. What this means is that the benefit during one year is slightly smaller than the benefit during the year before, not that there has been net harm during that year. Geere seems to have misunderstood Tol’s graph.
My points about probably fewer droughts and probably richer biodiversity are grounded in the peer reviewed literature. Many models and data sets agree that rainfall is likely to increase as temperature rises, while the evidence for global greening as a result of carbon dioxide emissions (and rainfall increases) is now strong. Greater yields means more land sparing as well.
The main point I was trying to make is that very few people know that climate change has benefits at all, let alone net benefits today; even fewer know that it is likely to have net benefits in the future for about 70 years. This fact, which Mr Geere confirms, is worth discussing. Judging by the incredulous reaction to my article in some quarters, this was indeed news to many people.
I note Mr Geere has nothing to say about the harm being done by climate policies to the very poorest people in the world. A peer-reviewed estimate is that 200,000 people are dying every year because of the effect of biofuels on food prices. Western elites may feel comfortable about this, but I do not, and I think a serious debate about whether some current policies (as opposed to others) do more harm than good even in the long run is worth having.
2. Barry Brill.
I was intrigued by Barry Brill’s comment on my article, posted at Bishop Hill website, which argued that I had probably been conservative in my assessment of net benefits:
“The 1°C rise mentioned by Mr Geere has its base in 2009. As the IPCC says that global surface temperatures have increased by 0.85°C since the pre-industrial era, this point of maximum benefit is about equal to the 2°C target set by all UNFCCC conferences since Copenhagen.
At the rate of warming recorded in the recent AR5WG1 SPM (0.12°C/decade since 1951) it will be well after 2100 before even this level of diminishing benefit is reached. The IPCC says that the historic rate won’t increase unless the TCR is above about 1.5°C – which seems unlikely in view of recent studies.
The series of published economic studies relied upon by Professor Tol are based on the IPCC’s earlier assessment reports, which were blithely unaware of the “hiatus”. Allowance needs to be made for at least three new factors:
(1) The hiatus has already set the timetable back by about 17 years; (2) The models assumed a Best Estimate for ECS of 3.0°C. The consensus behind that figure has now evaporated; (3) We now know that natural variation (or the Davy Jones hypothesis) regularly offsets the effects of AGW.
All these factors suggest that Matt Ridley’s timing is extremely conservative. Any warming occurring in the 21st century is likely to be a great boon to planet Earth and its inhabitants.”
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