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It is difficult to know where to begin in response to Jim Ring's letter (NZ Skeptic 110), but somewhat reluctantly, here goes.

He writes, "But he never makes a case; he only quotes opinion". Well, I gave references for all my arguments, so let me take just one. I quoted from the latest report from Sir Peter Gluckman, NZ's Chief Science Adviser (www.pmcsa.org.nz ). He and all the others involved in compiling the report were giving their 'opinion', but I think most people would regard it as an 'expert opinion'. So yes, on that basis, I am guilty as charged.

I am afraid Mr Ring's knowledge of Law is a little sketchy. Expert opinion is often called for in legal cases from specialists in various fields and I can claim personal experience of this, having been asked for my 'opinion' by solicitors in Edinburgh.

His statement that "the earth is not warming", is truly extraordinary. Even the most hardened sceptics/denialists don't claim that. For example, Chapter 2 of the Heartland Institute booklet, "Nature, not Human Activity, Rules the Climate" is headed, "How much of Modern Warming is Anthropogenic?" Their website is a denialist's delight, but even they acknowledge the fact of global warming. Readers may wish to know that this august body has been defending the tobacco companies for many years (see Merchants of Doubt by Oreskes and Conway).

Regarding extreme weather and insurance companies, he fails to quote any references in support of his claim that extreme weather events have decreased. Let me quote: "Global natural disasters in 2013 combined to cause economic losses of $192 billion USD, 4% below the ten year average of $200 billion. The losses were generated by 296 separate events, compared to an average of 259." These figures come from the annual Executive Summary produced by Aon Benfield. Their website (www.aonbenfield.com/catastropheinsight) is worth visiting, as all the disasters are listed.

Finally, the clincher according to Mr Ring is: "The Great Global Warming Scam fell to pieces with the release of the Climategate emails in 2009". Much further on he refers to the dishonesty of so-called climate scientists. The inference is that all climate scientists are to be regarded as dishonest. What evidence does he have for this?

I suspect he is well aware of the fact that no fewer than five official investigations were conducted. Not one found evidence of malfeasance or anything that would weaken the fundamental results of climate science. Perhaps the best summing up was done by US News and World Report:"Climategate: Science not faked, but not pretty"

I would like to finish there, but there are a couple of other statements made in his previous letter (NZ Skeptic 108) which need to be addressed. "Antarctica is gaining ice". Well, yes in part. Currently sea-ice is increasing in East Antarctica and its ice-cap may be getting colder, for which we should all be grateful, but West Antarctica is losing ice mass. Interested readers should look to the journal Nature Climate Change for information on the Pine Island Glacier ( PIG), which discharges into the Amundsen Sea. The latest report says: "Over the past 40 years, PIG has thinned at an accelerating rate, making it the largest single contributor to sea-level rise in West Antarctica". The glacier covers an area some two thirds the size of the UK.

Finally and I do mean finally, his statement that "The idea of a greenhouse gas is pseudoscience", is quite sad. Of course the 'greenhouse' gases - water vapour, CO2, methane etc do not function in the same way as a greenhouse and every climate scientist knows that. It has merely become the accepted shorthand which identifies the subject to both scientists and laymen. In the on-line university course I am currently taking on The Science of Climate Change, this was the very first point made.

Should Mr Ring decide to reply to this, then I shall let somebody else take up the cudgels for Anthropogenic Global Warming. (abridged)

Keith L Muir

Moderate warming produces net benefits

NZ Skeptic 109 had a response from Keith Muir to my item suggesting that climate change would be a positive experience unless and until the global mean surface temperature (GMST) rises by a further 2°C. Although Keith says "there is plenty of evidence" to show me wrong, he doesn't produce any. I really don't believe that any such evidence exists.

The weighing of aggregate benefits and detriments from small movements in the GMST is undertaken with 'integrated assessment models' (IAMs) linking IPCC climate impact models with welfare economics models. The results of all 14 published valuations are brought together by Richard Tol1. Tol's graph shows that the aggregate welfare-equivalent impact remains positive until global temperatures increase more than 2.25°C above 2009 levels. Similar findings influenced the UNFCCC to recommend GMST be kept below 2°C from pre-industrial levels. Lesser warming is clearly not 'dangerous'.

Fortunately, GMST has been decreasing during the 21st century, and last year's IPCC AR5 projections suggest that there is little chance of the 2°C warming level being breached by 2100. The only real threats are the extreme events called 'abrupt climate change' which are rated as "very unlikely" - ie less of a threat than the next Ice Age.

Those modelled projections were run well before the Stockholm meeting at which the IPCC officially recognised the 15-year "warming hiatus" of 1998-2012. That meeting criticised the models as "running hot" and rejected the projections in favour of a much lower "assessed" table of forecast temperatures. Even the calculator on the Skeptical Science website2, whose raison d'etre is to rebut the arguments of climate skeptics, shows global cooling since 2002 in all the major databases.

Keith Muir cites somebody as believing that 'extreme weather' is becoming more frequent. Whatever induced her belief, it wasn't science - it contradicts both the data (Pielke Jr) and the IPCC's door-stopper 2012 SREX report.

Those interested in evidence-based science should read the amicus curiae brief3 currently being considered by the US Supreme Court. Pages 19-28 contain a concise summary of three compelling arguments advanced by skeptical scientsts. (abridged)

Barry Brill

Paihia

1. Tol, RSJ, 2009. The Economic Effects of Climate Change. Journal of Economic Perspectives 23(2) : 29-51.
2. skepticalscience.com/trend.php
3. tinyurl.com/lxjxnky