New publication: Does it matter if the consensus on anthropogenic global warming is 97% or 99.99%?

New publication: Does it matter if the consensus on anthropogenic global warming is 97% or 99.99%?

Cross-posted at Skeptical Science

The 97% consensus on anthropogenic global warming (AGW) reported by Cook et al. (2013) (C13) is a robust estimate. Alternative methods, such as James Powell’s, that identify only explicit rejections of AGW and assume that all other instances are endorsements, miss many implicit rejections and overestimate the consensus.

The C13 method can be modified and used to estimate the consensus on plate tectonics in a sample of the recent geological literature. This limited study—not surprisingly to anyone familiar with the field—produces a consensus estimate of 100%. However, among the abstracts that expressed an opinion. only implicit endorsements of the theory were found: this underlines the importance in consensus studies of identifying implicit statements. The majority of the abstracts expressed no position. Assuming that these cases suggest either uncertainty about, or rejection of, plate tectonics (as some critics of C13 have claimed about AGW) would lead to the absurd conclusion that the theory is not widely accepted among geologists.

Opinion surveys show that the public is misinformed about true state of consensus among climate scientists, with only a minority aware that it is greater than 90%. The difference between 97% and 99.99% is tiny compared to this gap. The 3% of published papers that reject AGW are contradictory and have invariably been debunked. They do not therefore provide a coherent alternative account of climate science. Despite this, dissenters are awarded disproportionate attention by ideologically and commercially motivated interests, as well as by false balance in the media. Countering this public confusion requires both communicating the consensus and debunking bad science.

For a shorter summary than the one below, read Dana Nuccitelli’s Guardian piece: Is the climate consensus 97%, 99.9%, or is plate tectonics a hoax? Continue reading

Keeping oil sands in the ground is not a “charade”

Keeping oil sands in the ground is not a “charade”


If the world is successful in reducing emissions sufficiently to avoid dangerous climate change, there is a limited future for a prospering oil-sands sector in Canada. The conventional wisdom among the Canadian establishment is that growing the oil-sands business is compatible with meeting national and global emissions commitments. This is a myth that obscures government policy contradictions.

In a recent Globe and Mail article Environmentalists should end the charade over the oil sands, Martha Hall Findlay and Trevor McLeod argue that keeping oilsands in the ground and stopping new oil pipelines will actually increase global greenhouse gas emissions.

Their argument rests on two premises:

  • Oil demand won’t start to fall until 2040. After that it will remain high for many years.
  • Oil-sands production is becoming less emissions intensive thanks to improving technology. If oil-sands consumption by US refineries were replaced by, say, more emissions-intensive Venezuelan heavy crude, then global emissions would increase.

I won’t dispute the second point in detail, at least for now. The case I’m making here does not depend on rebutting it. If overall oil-sands upstream emissions intensities really are falling due to improved technology, that’s welcome news. But I haven’t seen the most recent average emissions data that back it up. My understanding is that newer projects are predominantly in-situ facilities that are more emissions intensive than mines, so that the average GHG emissions per barrel is actually rising slowly.

My focus here will be the first point, where Hall Findlay and McLeod made an important error by misrepresenting the scenarios from the IEA’s World Energy Outlook 2016. They wrote: Continue reading

The looming irrelevance of big oil

The looming irrelevance of big oil

This a long piece that would probably be better split up into several separate, focussed articles. Never mind, consider it as a rambling, idiosyncratic and opinionated mind-dump on the subject of the future of oil. I may later rewrite parts of it more coherently and rigorously for a wider readership. As I make my way through the recently published IEA WEO 2016, I will provide updates.

Pioneers or pariahs?

James Gandolfini, the late actor who played the gangster boss Tony Soprano, was once asked what profession he would never have wanted to have pursued. He answered: “an oilman” (video at 5:00). Those of us who have followed careers in the oil industry might be a little surprised, but not really that shocked, by a response like that.  To many people, oil companies and the people who work in them are often seen as the embodiment of greed and environmental destruction. Oilmen get used to being thought of as pariahs. Continue reading

Carbon budgetting

Carbon budgetting

Originally published online at Corporate Knights Magazine on May 18, 2016 and in the hardcopy magazine in June 2016.

The Paris Agreement on mitigating climate change seeks to limit emissions with the goal of holding the increase in the global average temperature to well below 2 C above preindustrial levels while also pursuing efforts to limit the temperature increase to 1.5 C.

As with any complicated international deal, the devil is in the language. While it acknowledges that developing countries will take longer to peak their greenhouse gas emissions, it agrees that these reductions will be made on the basis of equity.

parisagreement1

This phrasing, “basis of equity,” probably means very different things to different parties to the agreement. The Kyoto Protocol adopted in 1997 was based on the principle of “common but differentiated responsibility,” which is to say that developed countries, with their disproportionate historic responsibility for past emissions, were expected to cut sooner and deeper. This same language is still used in the Paris Agreement reached last year. Continue reading

Consensus on Consensus

Consensus on Consensus

Originally published in Corporate Knights Magazine

studies_consensus

In 1998 and 1999, American scientists Michael Mann, Raymond Bradley and Malcolm Hughes published two papers that reconstructed the average temperatures of the northern hemisphere back to the year 1000. The articles showed a temperature profile that gently declined from 1000 to 1850, fluctuating a little along the way, with a sudden increase in the late nineteenth and the twentieth centuries.  The graph was nick-named “the Hockey Stick”, with its long relatively straight handle showing the stable pre-industrial climate and the blade representing the sudden uptick in the last 150 years.

The diagram was a striking depiction of the abrupt warming that had occurred since the Industrial Revolution compared to what happened before. For those opposed to the scientific consensus on Anthropogenic Global Warming (AGW), the Hockey Stick posed a threat and had to be broken. Continue reading

James Powell is wrong about the 99.99% AGW consensus

James Powell is wrong about the 99.99% AGW consensus

In a recent article in Skeptical Inquirer, geologist and writer James Lawrence Powell, claims that there is a 99.99% scientific consensus on Anthropogenic Global Warming (AGW). You might think that after all of the harsh criticism that the 2013 Cook et al. paper (C13) has received from climate contrarians that we would be pleased to embrace the results of a critique that claims we were far too conservative in assessing the consensus. While it certainly does make a nice change from the usual rants and overblown methodological nit-picks from the contrarians, Powell is wrong to claim such a very high degree of agreement.

He makes many of the same errors that contrarian critics make: ignoring the papers self-rated by the original authors; and making unwarranted assumptions about what the “no-position” abstracts and papers mean.

Powell’s methodology was to search the Web of Science to review abstracts from 2013 and 2014. He added the search term “climate change” to the terms “global climate change” and “global warming” that were used by C13.  He examined 24,210 papers co-authored by 69,406 scientists and found only five papers written by four authors that explicitly reject AGW. Assuming the rest of the abstracts endorsed AGW, this gives consensus figures of 99.98% (by abstract) and 99.99% (by author).

His definition of explicit rejection would align roughly with the seventh level of endorsement used in C13: “Explicitly states that humans are causing less than half of global warming” . In the abstracts from 1991-2011, C13 found 9 out of 11,914 that fit level 7, which using Powell’s consensus calculation assumptions, would yield 99.92%. So, there is probably not much difference between the two approaches when it comes to identifying an outright rejection paper. It’s what you assume the other abstracts say—or do not say—that is the problem.

C13 also counted as “reject AGW” abstracts that: “Implies humans have had a minimal impact on global warming without saying so explicitly, e.g., proposing a natural mechanism is the main cause of global warming”. These are more numerous than the explicit rejections and include papers by scientists who consider that natural causes are more important than human causes in recent warming, but who do not outright reject some small human contribution.

pacmen2

Competing Climate Consensus Pacmen. Cook on the left, Powell on the right.

Continue reading

The Road to Two Degrees, Part Three: Equity, inertia and fairly sharing the remaining carbon budget

The Road to Two Degrees, Part Three: Equity, inertia and fairly sharing the remaining carbon budget

Previously published at Skeptical Science on December 9th, 2015

In the first part of this series, I examined the implications of relying on CCS and BECCS to get us to the two degree target. In the second part, I took a detailed look at Kevin Anderson’s arguments that IPCC mitigation scenarios aimed at two degrees are biased towards unproven negative-emissions technologies and that they consequently downplay the revolutionary changes to our energy systems and economy that we must make very soon. In this last part, I’m going to look at the challenges that the world faces in fairly allocating future emissions from our remaining carbon budget and raising the money needed for climate adaptation funds, taking account of the very unequal past and present.

Until now, economic growth has been driven and sustained largely by fossil fuels. Europe and North America started early with industrialization and, from 1800 up to around 1945, this growth was driven mainly by coal. After the Second World War there was a period of rapid (~4% per year) economic growth in Europe, N America and Japan, lasting about thirty years, that the French refer to as Les Trente Glorieuses, The Glorious Thirty. This expansion was accompanied by a huge rise in the consumption of oil, coal and natural gas. After this there was a thirty-year period of slower growth (~2%) in the developed economies, with consumption fluctuations caused by oil-price shocks and the collapse of the Soviet Union. During this time, oil and coal consumption continued to grow, but not as steadily as before. Then, at the end of the twentieth century, economic growth took off in China, with a huge increase in the consumption of coal.

Source of the emissions data is from the CDIAC. See the SkS post The History of Emissions and the Great Acceleration for further details.

If we are to achieve a stable climate, we will need to reverse this growth in emissions over a much shorter time period, while maintaining the economies of the developed world and, crucially, allowing the possibility of economic growth for the majority of humanity that has not yet experienced the benefits of a developed-country middle-class lifestyle.

Here are the the annual emissions sorted by country and region:

From Chancel and Piketty (2015) Continue reading

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