Archive for the ‘Scientific Consensus’ Category


Scientific Guide to Global Warming Skepticism

21 December 2010

The Skeptical Science team (which includes myself) have recently completed a 16-page booklet called The Scientific Guide to Global Warming Skepticism. (Actually it was completed a fortnight ago, but I forgot to link to it at the time. Anyway, better late than never.)

To quote John Cook’s blog post launching the Guide:

Scientific skepticism is healthy. In fact, science by its very nature is skeptical. Genuine skepticism means considering the full body of evidence before coming to a conclusion. However, when you take a close look at arguments expressing climate ‘skepticism’, what you often observe is cherry picking of pieces of evidence while rejecting any data that don’t fit the desired picture. This isn’t skepticism. It is ignoring facts and the science.

The Scientific Guide to Global Warming Skepticism looks at both the evidence that human activity is causing global warming and the ways that climate ‘skeptic’ arguments can mislead by presenting only small pieces of the puzzle rather than the full picture.

The Guide explains the science in brief, plain language without getting too technical. For those who wish to dig deeper into the science, more detailed treatments can be found at the following pages (often presented with varying levels of complexity from Basic to Advanced):


The Fake Scandal of Climategate

23 November 2010

This post was written for Skeptical Science as the first part of a series on the fake scandal of Climategate.

It’s bad enough that global warming contrarians are successfully misleading the public by propagating misconceptions about climate science. But recently it has become popular to attack climate scientists themselves, to accuse them of fraud and conspiracy. Exhibit No. 1 of the climate conspiracy theory is a collection of emails stolen (or possibly leaked) from the Climatic Research Unit (CRU) of the University of East Anglia (UEA), which appeared on the internet in November 2009.

Founded in 1972, CRU is only a small research unit with around 16 staff. CRU is best known for its work, since 1978, on a global record of instrumental temperature measurements from 1850 to the present, or CRUTEM. CRU’s land surface temperatures are combined with the UK Met Office Hadley Centre’s sea surface temperatures to form the global land-ocean record HadCRUT. CRU has also published reconstructions of pre-1850 temperatures based on tree rings, and CRU scientists have been involved in the Intergovernmental Panel on Climate Change (IPCC).

The 1,073 emails span 13 years of correspondence between colleagues at CRU. Much of it is mundane, but in this digital age it took only a matter of hours for contrarians to do some quote-mining. Contrarians alleged that the CRU scientists had manipulated data to support predetermined conclusions, that they had stonewalled Freedom of Information (FoI) requests for data, and that they had corrupted the peer review and IPCC processes.

The story was quickly dubbed “Climategate”, and it spread rapidly from arcane contrarian blogs through conservative columnists to the mainstream media. The hyperbole was turned up to eleven. Conspiracy theorists had a field day, claiming that anyone even mentioned in the emails, or remotely connected to CRU, must also be part of a conspiracy. In this way, the Climategate conspiracy theory snowballed to include the entire field of climate science. The Climategate emails were held up as “the final nail in the coffin of anthropogenic global warming”, and the media were only too happy to play up the controversy.

The CRU scientists have been cleared

In the months that followed, there were several inquiries into the allegations resulting from the emails. When a few of the more suggestive email quotes are reeled off by pundits without much context, they can sound pretty damning. But each and every one of these inquiries has found no fraud and no conspiracy. Read the rest of this entry ?


Americans Know Nothing About Climate Change

19 October 2010

A new survey of 2,030 American adults (weighted according to demographics and political party allegiance) confirms what previous surveys have suggested: that the American public’s understanding of climate change is dismal. The researchers graded the participants based on percentage of questions answered correctly (although some questions were harder than others). A majority, 52%, received an F. 25% got a D, 15% a C, 7% a B, and only 1% got an A.

I am not aware of any similar surveys of Australians — I hope we are not quite as bad, but there is a powerful climate change denial lobby here too. For context, it’s not just climate science about which Americans are ignorant; it is part of a larger problem of general scientific ignorance. Surveys have consistently found that about 40% of Americans think the Earth is only a few thousand years old; about 20% do not know that a year is the time it takes the Earth to orbit the Sun.

The results are pretty depressing considering that the US is a democracy:

  • Only 63% of Americans say global warming is happening. 19% think not, and 19% are not sure.
  • Only 50% say humans are the main cause of the current warming (compared to roughly 97% of publishing climatologists). 35% say natural changes are the main cause.
  • Only 39% say that most scientists agree global warming is happening; 38% think there is a lot of disagreement among scientists. (Clearly the contrarian line of “no scientific consensus” is working.) Read the rest of this entry ?

Do the IPCC use alarmist language?

14 October 2010

This post was written for Skeptical Science.

Graham Wayne has recently written rebuttals to “The IPCC consensus is phony” and “IPCC is alarmist”. But, you might say, that’s only half the story – do the IPCC present their conclusions in an alarmist way? There are many different ways you might look at this, but one of the more important ones is how the IPCC present probabilities (or “likelihoods”).

Thinking about probability does not come intuitively to the human mind. Our assessment of a risk often depends on how the probability is presented.

Suppose you are about to get on a plane and a reliable source tells you that there is a 1% chance that the plane will crash during your flight. Do you still want to get on the plane? I’m guessing you’d be having second thoughts about it.

What if the probability of a crash is 1 in 20? 1 in 10? 1 in 3? You’d probably run away screaming.

I’ll get to the point of all this shortly, but please bear with me and consider the following quote from the IPCC’s Fourth Assessment Report (AR4):

It is very unlikely that [Atlantic Ocean circulation] will undergo a large abrupt transition during the 21st century. [Source]

Are you alarmed yet? Is this an example of the IPCC using alarmist language in reporting its conclusions? Read the rest of this entry ?


Skeptical Science posts

25 September 2010

I haven’t been posting very often recently, and one reason is that I’ve been busy writing for another climate blog called Skeptical Science which, unlike mine, actually has a readership. Skeptical Science is run by John Cook, and basically the core of the site is an increasingly comprehensive database of rebuttals to the arguments of global warming “skeptics” (currently it includes rebuttals to no less than 122 arguments). The site has been a major inspiration for me, particularly its politically neutral fact-based approach (unlike some other climate blogs I could name).

Earlier this year I started posting comments on Skeptical Science giving detailed feedback on how to improve the site, most of which John adopted. Then a few weeks ago, John announced that the site would now include basic, intermediate, and advanced versions of each rebuttal, and asked for volunteers to help write the basic versions. So, long story short, I’ve written a number of basic rebuttals for Skeptical Science:

The empirical evidence that humans are causing global warming

Is climate science settled? Especially the important parts?

Plain english rebuttal to ‘Global warming isn’t happening’ argument

I will continue to make contributions to Skeptical Science and will link to them.


Global Warming Contrarians Part 7: State of the Climate

4 August 2010

Claim: There’s no evidence that the global climate is warming. Why worry about a problem that’s invisible?

Fact: Just about any aspect of climate you care to look at does show signs of global warming.

The US National Oceanic and Atmospheric Administration have recently released their 20th annual State of the Climate report. The report is ostensibly about the climate in 2009, but because 2009 was the end of a decade the authors decided to take a longer-term view.

According to the press release, the report

draws on data for 10 key climate indicators that all point to the same finding: the scientific evidence that our world is warming is unmistakable. More than 300 scientists from 160 research groups in 48 countries contributed to the report, which confirms that the past decade was the warmest on record and that the Earth has been growing warmer over the last 50 years. Read the rest of this entry ?


Scientific Opinion versus Media Balance

2 August 2010

Renegade Conservatory Guy has created an infographic showing the discrepancy between scientific opinion on global warming and public opinion. I think this speaks for itself.