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.

Observations

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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Have we turned the corner on emissions?

One of these days, the world will get its act together and halt the growth in CO2 emissions. This week, the International Energy Agency reported that the rise in emissions did indeed stall in 2014. According to the announcement, this was the first time in forty years that IEA emissions did not increase, except in years of economic weakness.

When we start to turn the emissions corner for good, this is what it will look like. Although halting emissions growth does not yet put us on the path to meeting the 2°C target, it does at least mean that we might not be destined to follow the business-as-usual path to disaster along the worst-case RCP8.5 pathway. At least we are not going as fast along that road.

Chris Mooney, Climate Nexus and Joe Romm have articles on this, all worth reading.

The IEA announcement was a teaser: we are going to have to wait until June 15, 2015 to see the details of the analysis. In the meantime, I thought it would worthwhile looking at some data to see how confident we can be that this really is a positive signal that we can discern out of the noise and uncertainty.

First, let’s plot year-to-year growth in CO2 emissions, along with global GDP growth, against time:

IEA1

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Does providing information on geoengineering reduce climate polarization?

This article was originally published at Skeptical Science on March 4, 2013.

Dan Kahan of Yale University and four colleagues have just published an article in Annals of the AAPS titled: Geoengineering and Climate Change Polarization Testing a Two-Channel Model of Science Communication that investigates the effect on study participants’ attitudes to climate change after reading an article about geoengineering. In their abstract, they write:

We found that cultural polarization over the validity of climate change science is offset by making citizens aware of the potential contribution of geoengineering as a supplement to restriction of CO2 emissions.

I will argue here that this experiment achieved no such result because the premise was wrong. Specifically, the information on geoengineering that was presented to the study participants (in the form of a fictional newspaper article) bears no relation to mainstream scientific opinion on geoengineering nor, even, to the opinions of advocates of geoengineering. Geoengineering is portrayed in the fictional newspaper article as a strategy with no uncertainty about how well it might work and, it is claimed, will “spare consumers and businesses from the heavy economic costs associated with the regulations necessary to reduce atmospheric CO2 concentrations to 450 ppm or lower”. This is hardly depicting geoengineering as a “potential solution” or “a supplement” to the restriction of emissions, as is claimed in the abstract of the paper.

In fact, what Kahan et al. have demonstrated is that presenting misinformation dressed up as fact can affect people’s opinions about climate change. That may be interesting as a social science experiment conducted on consenting adults, but it is not much use as a guide to effective public science communication, constrained as it is to tell the truth.
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