Understanding Climate Risk

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Archive for the ‘Science communication’ Category

McLean follow up

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Elaine McKewon book-ended my letter to the editors of Fairfax papers The Age and Sydney Morning Herald regarding the publishing of John McLean’s error-ridden piece on the IPCC (the editors, by the way, have not responded) with a terrific take down of McLean in Crikey.

She questioned McLean’s byline on the original article, to whit:

John McLean is the author of three peer-reviewed papers on climate and an expert reviewer for the latest IPCC report. He is also a climate data analyst and a member of the International Climate Science Coalition.”

asking “But is that accurate? Who is John McLean? What qualifications entitle him to speak as an expert on climate science? What is the ICSC, and which groups, interests and agendas do McLean and the ICSC represent? What exactly does it mean to be an “expert reviewer” of IPCC reports?”

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BoM Annual Climate Statement 2013 – quick links

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On Friday Jan 3, the Australian Bureau of Meteorology released its Annual climate statement 2013. The headline statements include:

Data collected and analysed by the Bureau of Meteorology show that 2013 was Australia’s warmest year on record while rainfall was slightly below average nationally.

  • Summer 2012–13 was the warmest on record nationally, spring was also the warmest on record and winter the third warmest
  • Overall, 2013 was Australia’s warmest year on record: annual national mean temperature was +1.20°C above average
  • All States and the Northern Territory ranked in the four warmest years on record
  • Nationally-averaged rainfall was slightly below average for the year, with 428 mm (1961–1990 average 465 mm)
  • Rainfall was mostly below average for the inland east and centre, and above average for the east coast, northern Tasmania and parts of Western Australia

The statement was widely reported – two good summaries by the BoM crew and Lewis and Karoly can be found on The Conversation. One of the biggest talking points was that 2013 was a normal year meteorologically – no El Niño in sight – but the temperature was still a record. Much of the reporting in Australia pointed out the disjuncture between observations and current government policy. The Australian Science Media Centre also had a rapid round-up that included some words from me.

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How to read an IPCC report

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By Roger Jones, Victoria University and Celeste Young, Victoria University

The Intergovernmental Panel on Climate Change (IPCC) is the accepted global authority on climate change. It produces reports that are collectively agreed assessments of the scientific literature by leading researchers. The Fifth Assessment Report (AR5) is being delivered over 2013–2014, starting this weekend.

What an IPCC report is

An Intergovernmental Panel on Climate Change (IPCC) report is an assessment that collects and summarises current knowledge in relation to climate change. This is done using literature from peer reviewed and unreviewed (grey) sources.

It is considered the leading review globally of climate change and is produced by a team of hundreds of scientists and specialists from a diverse range of disciplines.

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Time to stop hiding behind warming trends

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Time to stop hiding behind warming trends

By Roger Jones, Victoria University

Dr Rajendra Pachauri, head of the IPCC, has reportedly acknowledged to Graham Lloyd of The Australian, that there is a “17-year pause in global temperature rises”, a fact that apparently has been suppressed in Australia. Dr Pauchauri endorses debate, saying that people had a right to question the science, whatever their motivations.

But according to Lloyd, Pachauri’s views contrast with arguments in Australia that views outside the orthodox position of approved climate scientists should be left unreported.

Am I an “approved” climate scientist? because I don’t hold that view, nor do I know any who does. What we would like, though, is for science to be reported as science and for opinion to be reported as opinion. And for all reporting to be accurate.

Lloyd makes this claim: unlike in Britain, there has been little publicity in Australia given to recent acknowledgement by peak climate-science bodies in Britain and the US of what has been a 17-year pause in global warming. Britain’s Met Office has revised down its forecast for a global temperature rise, predicting no further increase to 2017, which would extend the pause to 21 years.

This is the Met Office’s latest five-year forecast shown below. Skeptical Science reports the Met Office saying: the latest decadal prediction suggests that global temperatures over the next five years are likely to be a little lower than predicted from the previous prediction issued in December 2011. We’re in the midst of a period of La Niñas, which have a slight cooling effect, as do rising sulphate emissions in Asia. But look at the blue line – do my eyes deceive me? Is it level with the previous black line? It’s warmer? Perhaps Lloyd’s computer has a tilt to the right that makes increases look level.

Observed (black, from Hadley Centre, GISS and NCDC) and predicted global average annual surface temperature difference relative to 1971-2000. Retrospective predictions starting from June 1960, 1965, …, 2005 are shown as white curves, with red shading representing their probable range, such that the observations are expected to lie within the shading 90% of the time. The most recent forecast (thick blue curve with thin blue curves showing range) starts from November 2012. All data are rolling annual mean values. The gap between the black and blue curves arises because the last observed value represents the period November 2011 to October 2012 whereas the first forecast period is November 2012 to October 2013. UK Met Office

The Met Office predicts record global mean temperature over the next five years – now that’s news.

News Corporation sells roughly 70% of the newspapers in metropolitan Australia, and its readers are subject to this kind of fudging on a regular basis. It’s no wonder some “approved” scientists are frustrated.

But that’s not the only thing that frustrates me. It is also time to challenge what Lloyd calls the orthodox position of climate science.

Climatology needs to stop hiding behind long-term trends and explain what is in plain sight, and why variations in the rate of warming might be important. I’m working with colleagues at the moment on a National Climate Change Adaptation Research Facility project called Valuing Adaptation to Rapid Change and we’re looking at the economics of rapid change. Non-linear behaviour in climate driving extreme events has the potential to really hurt us.

The first thing to bear in mind is that a trend line is a model. A warming trend is not a theory of how climate changes. If a complex, non-linear system fails to follow a trend, look at the model to see whether it represents the theory sufficiently well.

In a nutshell, the theory says greenhouse gases act like a blanket, trapping heat near the surface. This creates a radiation imbalance at the top of the atmosphere. The earth system warms to return this balance by increasing the heat escaping from the top of the atmosphere so that energy out equals energy in. This is a slow process, taking centuries, because the ocean has to warm sufficiently to support a hotter atmosphere. The scientific confidence in this aspect of climatology is extremely high. A simple trend line is sufficient to measure this process.

But on decadal time scales, the trend-line model fails. Most of the heat trapped in the earth system goes into the oceans. The top 700m of ocean increased in heat content from 3 x 1022 Joules in 1997 to 10 x 1022 Joules in 2010, in a highly non-linear manner, due to mixing rates between the surface and deep ocean. The atmosphere holds as much heat as the top 3m of ocean, about 0.4% of the heat content above. Why on earth then, with highly non-linear processes in the ocean, would we expect a gradual warming trend in the atmosphere?

A paper I published last year shows that most of Australia’s warming occurred in two episodes, one in the late 1960s to early 1970s, when south west WA rainfall also decreased, and the other in 1997-98. The other finding was that most of this warming was anthropogenic. On decadal timescales, step and trend is a much better model for explaining warming than simple trends.

To me, the graph above makes perfect sense: mild trends separated by an instantaneous rise of about 0.3°C. By ignoring non-linearity and projecting future climate change as simple trends, orthodox science is doing us a great disservice. We have not yet woken up to the recent non-linear increases in heatwaves and fire danger in Australia let alone planning for more such changes in the future. The same goes for floods.

Observed and projected percentage area experiencing an exceptionally hot year: Queensland as an example. Note the recent rapid increase (source: K. Braganza, Bureau of Meteorology)

Days above high fire danger, average of 9 Victorian sites, showing statistically significant rapid increase (site data from Bureau of Meteorology)

It’s time to stop defending orthodox science by hiding behind simple trends and come to grips with the fundamental non-linearity of climate change. That’s the risk we need to mitigate, adapting to changes that can’t be avoided.

Roger Jones receives funding from the National Climate Change Adaptation Research Facility. He is affiliated with Climate Scientists Australia and the IPCC.

The Conversation

This article was originally published at The Conversation.
Read the original article.

Et tu, Chief Scientist?

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Less than a fortnight ago, I wrote that those barracking for conventional scientific theories often maintain that science is not a matter of belief. Sorry guys, but assessing the probability of t (scientific truth) being T (absolute truth), is a matter of belief, as is anything that goes on in the mind regarding external evidence. But there is a difference between belief and true belief.

And then in a conversation with the Chief Scientist Ian Chubb on communicating science, with specific reference to climate science, The Conversation quotes him as saying:

“We scientists need to talk about evidence, and without being cornered into answering questions like ‘do you believe?’,” Professor Chubb said.

“I get asked that every day and every now and then I make a mistake and say yes or no…It’s not a belief, it’s an understanding and an encapsulation and interpretation of the evidence.”


Ian Chubb was speaking to the Royal Society of Victoria, which launched on August 30th a three-year program aimed at increasing the awareness of science among primary school children. And while I agree with most of what Ian Chubb says in his interview with The Conversation, the belief thing should be called for what it is – a full-blown fallacy.

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Grauniad on Kuhn

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No, not an exotic Hungarian sandwich, but The Grauniad has an excellent 50th anniversary review of Kuhn’s The Structure of Scientific Revolutions written by John Naughton in their Sundy paper. In a total paradigm shift, the comments aren’t totally trolltown, either. See also, Howard Sankey on the The Conversation.

Before Kuhn, our view of science was dominated by philosophical ideas about how it ought to develop (“the scientific method”), together with a heroic narrative of scientific progress as “the addition of new truths to the stock of old truths, or the increasing approximation of theories to the truth, and in the odd case, the correction of past errors”

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Provoking comment and framing risk

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A couple of my recent forays into the media have provoked comment below the articles themselves and in emails sent querying particular points. They are worth unpacking because they reflect on the different between the straight communication of science and framing risk.

One was in reference to a recent op-ed in The Age. In it, I said:

If people accept the 0.0038 and 0.02 degree benefits as valid then they also accept the science behind a 5.3 degrees warming for business as usual (As in the emission scenario created by Treasury for the 2008 Garnaut Review). Who wants to live in a world warming by 5 degrees or more? Major food crops could not be grown in many parts of the world, projected sea level rise would be tens of metres, most of the shelled species in the ocean would not survive, ecosystems would be disrupted as the pace of change outstripped their ability to adapt and millions to billions of people would lose environmental security leading to mass migrations never before seen.

That prompted an email from an earth scientist wanting to know what peer-reviewed reference I was using for the projected tens of metres of sea level rise. I sent back this now famous diagram and a note saying that I wasn’t putting it on a timetable. He then replied suggesting that people could be misled into thinking that the date was 2100 (because that was tied to the two temperature measures) and that I was being alarmist. Because it would take thousands of years to be realised. Read the rest of this entry »