Unsure about how to talk about uncertainty? Read this

2015-07-05_15-39-46Adam Corner, Stephan Lewandowsky, Mary Phillips, and Olga Roberts have today published The Uncertainty Handbook, which is a twenty-page practical guide for climate communicators. It is excellent, clearly written and I recommend that everyone read it all. Adam Corner has a blogpost outlining the Handbook at Shaping Tomorrow’s World.

As the authors say, everyone is already familiar with making decisions under uncertainty. To make plans means accepting that they may not unfold as expected. The natural world is chaotic, with many known-unknowns and unknown-unknowns. The human world is even more unpredictable. We all develop rules-of-thumb to deal with everyday uncertainty: whether to take an umbrella, when to take a vacation, whose advice to trust. But we humans do not always have good instincts when it comes to grasping the uncertainty of novel and unfamiliar situations. As Daniel Kahneman showed in his masterpiece Thinking, Fast and Slow we are often not very smart when confronting probability or logic problems in our lives, especially when they are expressed numerically.  The Economist reviewer wrote:

In one experiment described by Mr Kahneman, participants asked to imagine that they have been given £50 behave differently depending on whether they are then told they can “keep” £20 or must “lose” £30—though the outcomes are identical. He also shows that it is more threatening to say that a disease kills “1,286 in every 10,000 people”, than to say it kills “24.14% of the population”, even though the second mention is twice as deadly. Vivid language often overrides basic arithmetic.

Framing is everything.

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You can now run a MOOC at your own pace, from July 1

The Denial 101x MOOC (Massive Open Online Course) was a great success, with thousands of participants and many satisfied students. I admit that I was quite touched by the mostly positive student reactions and I am thankful to John Cook for inviting me to contribute to this course in a small way. This video compilation of students’ feedback shows how people from diverse backgrounds all got something from the course.

From July 1, 2015 onwards, the course is available for anyone to follow at their own pace. It’s completely free of charge, naturally!

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Why the 97 per cent consensus on climate change still gets challenged

Here are some excerpts from an article I wrote  for the magazine Corporate Knights, that was published on May 14, 2015. Some references and links have been added at the end. This is cross-posted with Skeptical Science.

In 2004, science historian Naomi Oreskes published a short paper in the journal Science concluding there was an overwhelming consensus in the scientific literature that global warming was caused by humans.

After the paper’s release, there was some unexpectedly hostile reaction. This prompted Oreskes and her colleague Erik Conway to go even deeper with their research, leading to the publication of the book Merchants of Doubt. It documents how a small group of scientists with links to industry were able to sow doubt about the scientific consensus and delay effective policy on DDT, tobacco, acid rain and, now, global warming.

Fast forward to two years ago: a team of volunteer researchers (myself included) associated with the website Skeptical Science decide to update and extend Oreskes’ research. Led by University of Queensland researcher John Cook, we analyzed the abstracts of about 12,000 scientific papers extracted from a large database of articles, using the search terms “global warming” and “global climate change.” The articles had been published over a 21-year period, from 1991 to 2011.

As an independent check on our results, we also sent emails to the more than 8,500 scientist authors of these articles. (These were the scientists whose e-mail addresses we were able to track down). We asked them to rate their own papers for endorsement or rejection of man-made global warming.

Both approaches yielded a very similar result: 97 per cent of the scientific literature that expresses an opinion on climate change endorses the expert consensus view that it is man-made. The results were published in May 2013 in the journal Environmental Research Letters.

We were astonished by the positive reception. Mention of the paper was tweeted by U.S. President Barack Obama, Al Gore and Elon Musk, among others. Obama later referenced it in a speech at the University of Queensland, while U.S. Secretary of State John Kerry has referred to the 97 per cent consensus in recent speeches. John Oliver based an episode of his HBO comedy show Last Week Tonight around it, a clip viewed online more than five million times.

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Permafrost feedback update 2015: is it good or bad news?

This article was originally posted at Skeptical Science on April 20th, 2015

We have good reason to be concerned about the potential for nasty climate feedbacks from thawing permafrost in the Arctic. Consider:

  • The Arctic contains huge stores of plant matter in its frozen soils. Over one-third of all the carbon stored in all of the soils of the Earth are found in this region, which hosts just 15% of the planet’s soil-covered area.
  • The Arctic is warming at twice the rate of the rest of the planet. The vegetable matter in the soils is being taken out of the northern freezer and placed on the global kitchen counter to decompose. Microbes will take full advantage of this exceptional dining opportunity and will convert part of these plant remains into carbon dioxide and methane.
  • These gases will add to the already enhanced greenhouse effect that caused the Arctic warming, providing a further boost to warming. There’s plenty of scope for these emissions to cause significant climatic mischief: the amount of carbon in the permafrost is double the amount currently in the air.

But exactly how bad will it be, and how quickly will it cause problems for us? Does the latest research bring good news or bad?

Ted Schuur and sixteen other permafrost experts have just published a review paper inNature: Climate change and the permafrost feedback (paywalled). This long and authoritative article (7 pages of text, plus 97 references) provides a state-of-the-art update on the expected response of permafrost thawing to man-made climate change. Much of the work reported on in this paper has been published since the 2013 IPCC AR5 report. It covers new observations of permafrost thickness and carbon content, along with laboratory experiments on permafrost decomposition and the results of several modelling exercises.

The overall conclusion is that, although the permafrost feedback is unlikely to cause abrupt climate change in the near future, the feedback is going to make climate change worse over the second half of this century and beyond. The emissions quantities are still uncertain, but the central estimate would be like adding an additional country with the unmitigated emissions the current size of the United States’ for at least the rest of the century. This will not cause a climate catastrophe by itself, but it will make preventing dangerous climate change that much more difficult. As if it wasn’t hard enough already.


There’s a lot of information in this paper and, rather than attempt to describe it all in long form, I’ll try to capture the main findings in bullet points.

  • The top three metres of permafrost contain about 1035 PgC (billion tonnes of carbon). This is similar to previous estimates, but is now supported by ten times as many observations below the top 1 m depth. Very roughly, the deepest deposits richest in carbon are near the Russian, Alaskan and Canadian Arctic coasts, with the poorest in mountainous regions and in areas close to glaciers and the Greenland ice sheet.

perm4The carbon content in the top three metres of permafrost soils. From Hugelius et al (2013).

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Skeptical Science is running a MOOC

The volunteers at Skeptical Science, along with staff at the University of Queensland, have been busy over the past several months putting together a Massive Open Online Course (MOOC) on climate change. The course, Making Sense of Climate Science Denial, starts on April 28th and is free to anyone who wants to participate. It will last for seven weeks and will require an hour or two of attention every week.

The University of Queensland has a press release.

Thousands of people have already signed up, but we are hoping for many more. Learning will not just come from watching the many short video lectures we have prepared, but from discussions with fellow students. So, no matter what your level of knowledge, or  your point of view on man-made climate change might be, please join us. I’m looking forward to learning from this course, too.

All anyone needs is an Internet connection, a desire to learn and share your knowledge, and an ability to understand English spoken in American, British, Canadian and Australian accents.

Watch the trailer:

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The history of emissions and the Great Acceleration

One of my pastimes is downloading data and playing around with it on Excel. I’m not kidding myself that doing this means anything in terms of original research, but I do find that I learn quite a lot about the particularities of the data and about the science in general by doing some simple calculations and graphing the numbers. There’s even occasionally a small feeling of discovery, a bit like the kind that you experience when you follow a well-trodden path in the mountains for the first time:

We were not pioneers ourselves, but we journeyed over old trails that were new to us, and with hearts open. Who shall distinguish? J. Monroe Thorington

Anyway, I downloaded some historical emissions data from the CDIAC site and played around with it. To repeat, there’s nothing new to science here, but there were a few things that I found that were new to me. First, let’s look at historical emissions of CO2 from man-made sources from 1850 to 2010. Note that for all of these graphs there are no data shown for 2011-2015.

emm1What immediately struck me—something I hadn’t fully appreciated before—was how small oil consumption was before 1950. Both world wars were carried out without huge increases in oil use, despite the massive mobilizations of armies, navies and air forces. You can make out some downward blips in coal consumption for the Great Depression (~1930) and around the end of WW2 (~1945).

It wasn’t until after 1950 that fossil-fuel consumption went nuts. Some people have taken to calling this inflection point The Great Acceleration, there’s more on this later. Continue reading

Shell: internal carbon pricing and the limits of big oil company action on climate

Originally posted at Skeptical Science on March 24th, 2015.

Shell evaluates all of its projects using a shadow carbon tax of $40 per tonne of carbon dioxide. That’s great. But why is the company still exploring in the Arctic and busy exploiting the Alberta oil sands?

Of all of the big fossil-fuel companies, Shell has adopted perhaps the most constructive position on climate change mitigation. Recently, the company’s CEO, Ben van Buerden told an industry conference:

You cannot talk credibly about lowering emissions globally if, for example, you are slow to acknowledge climate change; if you undermine calls for an effective carbon price; and if you always descend into the ‘jobs versus environment’ argument in the public debate.

Shell employs engineer David Hone as their full-time Climate Change Advisor. Hone has written a small ebook Putting the Genie Back: 2°C Will Be Harder Than We Think, priced at just 99¢ and he writes a climate change blog that should be part of every climate-policy geek’s balanced diet.

Shell also has a position they call Vice President CO2, currently occupied by Angus Gillespie. Here’s Gillespie talking recently at Stanford on the company’s internal shadow carbon pricing strategy (hat-tip to John Mashey). It’s worth watching if only for Gillespie’s vivid example of the limitations of looking at averages. The slides can be downloaded here.

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