This appeared in the Letters section of The Canberra Times on 25 February 2013:

After years of claims to the contrary, UN climate chief Rajendra Pachauri’s acknowledgment of 17 years with no warming and none predicted to come is welcome progress, but it leaves much of the climate story untold.

Most importantly, this steady temperature has occurred despite constantly rising CO2 levels and a complete lack of correlation between CO2 levels and temperature change throughout the 150 years to which Pachauri refers.

This and other evidence tells us that CO2 is but a small part of a big, complex climate picture including solar variations, ocean heat transfer, cloud density, volcanic action, etc., and, quite possibly, some unknowns. It also means that any changes humanity makes to CO2 levels have little or no effect on climate. Hundreds of billions of dollars have been wasted at the behest of alarmists such as Pachauri trying to stop something that was not happening.

Acknowledgment is not enough – he owes the world an apology.

Doug Hurst, Chapman

This was followed by this, on the following day:

A number of well-informed climate change sceptics have been saying for some time in The Canberra Times letters pages that, despite huge increases in carbon dioxide emissions, the world has not warmed for the past 16 years. These statements have been met with abuse and ridicule. Now that Rajendra Pachauri, head of the Intergovernmental Panel on Climate Change, has acknowledged a 17-year pause in global warming, perhaps these critics will pause and reflect on what is really happening to our climate.

While this revelation does not mean the planet is no longer in danger from global warming, it does show that statements claiming the science is settled should be treated with great caution. We sceptics have been disparaged as deniers, but it seems to me that the real deniers are the climate change zealots who, despite changes in observed data, refuse to believe anything that does not support their apocalyptic view of the future.

H. Ronald, Jerrabomberra, NSW

On the same day (26 Feb), this appeared:

Those who prefer to get their science from scientists, rather than Andrew Bolt, will already be well aware that it is Doug Hurst (Letters, February 25) who owes us all an apology, not Rajendra Pachauri.

For those who are genuinely confused, but still prefer evidence and reason to prejudice and patronage, there is a very useful temperature chart that can be viewed at www.skepticalscience.com/graphics.php?g=47.

This chart show that the long-term temperature trend is rather like an escalator: a series of plateaus, such as we are currently experiencing, but each one higher than the last, so that the overall trend is consistently and increasingly upward.

For those wondering where all the heat energy from higher carbon dioxide concentrations has gone over the past 17 years, it’s worth noting the top 700 metres of the ocean had increased heat content from 3×1022 joules in 1997 to 10×1022 joules in 2010. As it has before, the global system will soon enough ”rebalance” that excess and average atmospheric temperatures will again rise. All that extra energy has to go somewhere.

Felix MacNeill, Dickson

These responses appeared on February 28:

I am disappointed to see comments from IPCC chief Dr Rajendra Pachauri misrepresented by Doug Hurst (Letters, February 25). Dr Pachauri’s recent comments highlighted a prolonged pause in global temperature increases, which is certainly different to saying that there has been no global warming in recent years, as claimed by Mr Hurst. While the upward trend in global temperatures has slowed since 1998, temperatures have remained at more than 0.5 degrees above the long-term average. The trend has slowed, but the warming signal is still well and truly there.

Dr Pachauri also continues to echo that there is strong evidence the global warming trend will continue into the future. During his recent address to the UN Climate Talks held in Doha, Qatar, in December 2012, Dr Pachauri confirmed: “Models project substantial warming in temperature extremes by the end of the 21st century. It is virtually certain that increases in the frequency and magnitude of warm daily temperature extremes and decreases in cold extremes will occur in the 21st century at the global scale.”

Comments on climate change are welcomed and constructive to the debate about the best approach to solving the issue. However, the misrepresentation of facts and science is irresponsible, and prevents the wider public from engaging properly in the conversation.

Michael Mazengarb, Monash

Doug Hurst (Letters, February 25) says there is “a complete lack of correlation between CO2 levels and temperature change over the last 150 years”. In fact, over the past hundred years, CO2 levels have risen steadily from near-natural levels while average global surface temperature has risen by about 0.8 degrees Celsius, making nonsense of Hurst’s assertion. Moreover, deviations over that century from a constant linear relationship have been shown to be due to temporary phenomena such as aerosol pollution, solar cycles and volcanoes, with the underlying relationship of increased anthropogenic greenhouse gases and temperature being clear.

Hurst’s assertion, that any changes humanity makes to CO2 levels have little or no effect on climate, is not a scientific statement unless he backs it up by reference to research proving it so; at present it stands as a faith-based statement. While climate is complex, the overwhelming evidence so far is that there is a significant risk for humans (though not a certainty) from increased greenhouse gas levels in the atmosphere. We would be crazy to ignore this risk just because there’s more to learn.

Paul Pollard, O’Connor

I wrote this, which appeared in The Canberra Times on Tuesday 5 March 2013:

Self-labelled climate “sceptics” such as H. Ronald (Letters, 26 Feb) and Doug Hurst (Letters, 25 Feb) are quick to trumpet a recent report in The Australian by Graham Lloyd which claimed that UN climate head Rajenda Pachauri had said that there had been a pause in global warming for the last 17 years.

They should know better than to trust The Australian’s reporting on climate science. An investigation by the Skeptical Science website (bit.ly/V2T8kY) has revealed that Lloyd’s article misrepresents Pachauri’s views.

Hardly surprising, given News Limited’s long track record of supporting climate denial and inaction on global warming. In fact, Graeme Lloyd was caught out just last month misrepresenting a scientific paper on sea level rise (bit.ly/YwV4lS).

A little more genuine scepticism would go a long way.

Matt Andrews, Aranda

This letter appeared on 7 March:

I watched the Leigh Sales interview of Professor Tim Flannery on the ABC last night, which presumably was meant to tease out Flannery’s recent claims that the extreme weather we have been experiencing is the result of climate change. It’s telling how soft Sales is with fellow travellers compared with for example, her somewhat excitable demolition of Tony Abbott last year.

Flannery has a well-known propensity to exaggerate, and his form in making dud predictions is legend, which qualifies him to be grilled mercilessly by Sales. Instead the interview was remarkable in what it left out.

While Sales did lamely mention the IPCC’s acknowledgement that the Earth has not warmed for some time, surely a first for the ABC, the obvious question she failed to ask Flannery was “You have made predictions that failed to materialise, most notable that a number of Australian cities would by now have run out of water, why should we believe you now?”

H. Ronald, Jerrabomberra, NSW

This then appeared in The Canberra Times on Friday 8 March 2013:

In his attack on climate change sceptics, including me, Matt Andrews (Letters, March 5) implies that sceptics are somehow misbehaving by using facts-based arguments. How silly of me. All along I thought the climate issue was about facts. And that the UN IPCC chief’s recent statement that we have not warmed for 17 years, with no warming forecast, is a most important fact – especially as it confirms very similar data from the UK Met Office (national weather service) just before Christmas. So too is the fact that this “pause”, as the alarmists call it, has happened despite constantly rising CO2 levels.

The basic alarmist case is that we face “dangerous and unprecedented warming”. Obviously, nothing dangerous is happening – other than in alarmist computer models, that is. As for the unprecedented claim, that too is wrong.

A report on March 4, 2013 from the Harvard-Smithsonian Centre of Astrophysics has concluded that “the 20th century is neither the warmest century nor the most extreme century in the last 1000 years” – that occurred during the Medieval Warm Period (800AD-1300 AD).

The alarmists’ forecasts have not been within a bull’s roar of reality, and I hereby declare victory for the sceptics. We have won on the strength of irrefutable facts. I don’t expect any apologies from the alarmists for their constant stream of abuse; a simple acknowledgment that the sceptics have been right all along will do.

Doug Hurst, Chapman

This appeared on Saturday 9 March. Peter Doherty is a Nobel Prize winner in the field of medicine.

Perhaps I’m missing something and Douglas Hurst (Letters, March 8) can enlighten me, but my understanding is that the medieval warm period was essentially a North Atlantic phenomenon. Even then, it was not as warm as what we’ve been experiencing recently and the general consensus among active climate scientists is that global mean temperatures were much cooler. On the other hand, both the United States and Australia have just endured their hottest summers since accurate record keeping began. Useful information on the climate, the extent of sea ice at the poles and so forth is available on the US National Oceanographic and Atmospheric Administration website. And maybe he could give us a better reference to the March 4, 2013 report from the Harvard-Smithsonian Center of Astrophysics that he cites. I would like to read it, but can’t find it, or any reference to it, online.

Peter C. Doherty
Microbiology and Immunology Department, University of Melbourne Medical School, Vic

This short comment appeared on 11 March:

Tim Flannery is 95 per cent correct. H. Ronald (Letters, March 7) is 95 per cent incorrect. It is therefore unsurprising that he should focus obsessively on the 5 per cent.

Felix MacNeill, Dickson

This letter also appeared on 11 March, from Professor Tony Eggleton, author of A Short Introduction to Climate Change:

Doug Hurst (Letters, February 25) and Felix MacNeill (Letters, February 26) both comment on the plateau in the trend of global warming. Hurst correctly points out that the global temperature is not simply controlled by carbon dioxide, but by many factors including the sun, ocean and volcanoes. MacNeill correctly points out that temperatures over the last 100 years have risen and plateaued and risen and plateaued. Neither explains why.

After World War II, resurgent industry fed all the products of burning fuel into the atmosphere, including carbon dioxide and sulfur dioxide. The latter converts to sulfuric acid droplets in the upper atmosphere which reflect the sun and cool the Earth. Greenhouse warming from the increased carbon dioxide was largely balanced by that cooling. After the Geneva Convention of 1979, industry cleaned up the sulfur dioxide in its smoke and the global temperature rose again – more quickly than it had pre-war.

Over the last 10 years, China has massively increased its consumption of coat, with little cleaning of the pollutants. Upper atmosphere sulfuric acid is back, the human induced sunshade is in operation, and this has partly balanced greenhouse warming from rising carbon dioxide (Kaufmann et al 2012, Proceedings of the National Academy of Sciences, www.pnas.org/content/108/29/11790.full). China is committed to cleaning its coal smoke. The temperature plateau will end and there is a mountain ahead.

Tony Eggleton, Aranda

This appeared on 13 March:

Peter Doherty (Letters, March 9) is unlikely to get a response from Doug Hurst concerning the need for “a better reference to the March 4, 2013, report from the Harvard-Smithsonian Centre of Astrophysics”, so allow me to observe that Mr Hurst may have mistyped (or misread) “2013″ when it should have been “2003″. The only relevant reference that I could find was to a paper by Drs Willie Soon and Sallie Baliunas, Proxy climatic and environmental changes of the past 1000 years in the journal Climate Research, vol. 23: 89-110, published in January 2003 (www.int-res.com/articles/cr2003/23/c023p089.pdf). A longer version was published in the journal Energy and Environment, Vol. 14, No. 2-3/ May 2003. The history of the controversy that this engendered is to be found at en.wikipedia.org/wiki/Soon_and_Baliunas_controversy.

The concluding sentence of the paper’s abstract reads: “Across the world, many records reveal that the 20th century is probably not the warmest nor a uniquely extreme climatic period of the last millenium” – which matches Mr Hurst’s claim fairly closely. Where he got the March 4 date from, I’ve no idea.

The Soon-Baliunas research was funded, directly and indirectly, by the American coal and petroleum industries (see the Wikipedia article for a summary).

Michael Saclier, Curtin

This appeared on 14 March:

Peter Doherty (Letters, March 9) wrongly dismisses the Medieval Warm Period as a North Atlantic phenomenon not as warm as today.

In reality, it was much more widespread and obviously a good deal warmer in places like Greenland, which really was green and supported farming of crops and cattle for generations until the Little Ice Age struck (for reasons unknown). Crops failed, cattle died, sea ice prevented fishing and the people perished. This and other evidence tells us that temperatures and change rates were both greater than at present.

As for the recent hot summers in Australia and North America, they are irrelevant.

It is the worldwide averages that count, and they have been stable for 17 years – helped, perhaps, by unusually cold northern winters.

Earth has been at least 10 degrees hotter and 5 degrees colder in the past and the tiny change of 0.74 degrees (International Planet Protection Convention figure) this past 150 years is quite unremarkable – unlike the total lack of correlation of rising CO2 and stable temperatures for 17 years, which is indeed something to remark on and ponder. CO2 is merely a bit player in a multi-faceted climate picture too complex to fully understand or control – unless, of course, you are Mother Nature and have been continually changing the climate without our help since the dawn of time.

Doug Hurst, Chapman

This short piece also appeared on 14 March:

Doug Hurst (Letters, March 8) quotes from a report said to be dated March 4, that “the 20th century is neither the warmest century nor the most extreme century in the last 1000 years”.

This quotation was actually from a paper published in March 2003 which has been thoroughly repudiated during the intervening 10 years.

The Medieval Warm Period was warmish in the lands around the north Atlantic, coolish in the southern hemisphere. Current global warming exceeds the (local) warming of the Medieval Warm Period both in magnitude and in rate of warming.

Tony Eggleton, Aranda

I responded with this (not yet published):

Doug Hurst (Letters, 8 March) calls for a fact-based discussion of climate, but then wheels out three laughably weak sources to support the notion that global warming has stopped.

He cites a News Limited report that IPCC chief Rajenda Pachauri had said that there had been a pause in warming for the past 17 years. This report has been disputed by the IPCC because it does not reflect Pachauri’s views. All the primary atmospheric temperature records – GISS (NASA), Hadley, the satellites, etc – show clear warming over this period. Even so, short-term peturbations in the atmospheric temperature are an almost trivial part of the big picture: the atmosphere receives only 2.3% of the heat accumulation due to global warming, whereas the oceans are absorbing 93.4% of the extra heat. The rest of the warming is of land and ice masses. Ocean heating, down to a depth of 2000 metres, is unequivocal – the data show very clear warming.

Hurst also mentions a report by the UK Met Office late last year as if it supported the idea that warming had stopped. This was a decadal prediction of global temperature over the coming years. It was widely trumpeted on climate denial websites as announcing a pause in warming, but in fact it predicted that warming would continue, and said that “we will see near-record levels of global temperatures in the next few years”.

Finally, Hurst appears to refer to a 2003 paper by Willie Soon and Sallie Baliunas, astrophysicists (not climate scientists), which purported to show that globally the Medieval Warm Period was warmer than the 20th century. The publication of this infamous paper, partly funded by an oil lobby group, led to overwhelming criticism of its dubious methods and data selection. Three of the journal’s editors resigned in protest at the paper’s publication. One of the scientists cited in the paper said that it was “so fundamentally misconceived and contains so many egregious errors that it would take weeks to list and explain them all.” It has well and truly been dismissed by mainstream science. There has since been a lot of comprehensive and soundly based work in the field, such as the publication in Science on 7 March this year of a temperature reconstruction by Marcott et al going back 11,000 years. It shows that the rate of warming over the last hundred years is utterly unprecedented over the entire period.

If this shambles of misattribution, misinterpretation and poor research is what passes for evidence in climate denial circles, it explains a lot.

Matt Andrews, Aranda.