Falsifying warming

Letters– Dangerous and at large From Shaun Russell It was quite a shock to open my copy of New Scientist and see the murderer of my wife and child staring out at me (14 April, p 8). My contribution to the debate about the Mental Health Bill now being considered by the British parliament is as follows. Existing UK law permits violent people with mental health problems to be detained. The man who was convicted of killing my wife and 6-year-old daughter in a cornfield in Kent in 1996 was diagnosed as having an “untreatable personality disorder”. He was classed as “bad” but not “mad”. So he was free to roam the streets, even though he was a known violent criminal, had told his therapists that he wanted to “kill children in the woods”, and

was begging to be treated for his disorder. If the new law had been in place, he could have been compelled to receive “appropriate treatment” even had he not been seeking it. Or he could have been detained – in which case I believe that my wife and child would still be alive today. I think risk assessments that are subject to review, with input from doctors, drug counsellors, police, probation officers, social workers and so on, could be consistent and reliable. I also believe that the provision of dedicated secure accommodation with modern therapeutic capacity could help to better manage the hard core of violent and dangerous people who are currently free in the community, and for whom it is only a matter of time before they injure or kill innocent members of the public. Bangor, Gwynedd, UK

The Wellcome Trust & New Scientist Essay Competition 2007

HOW WELL CAN YOU WRITE

5

Are you a current postgraduate student in science, engineering or technology? Can you captivate an audience with a lively, fresh 700-word article on your research and its implications for society? Then why not tell the world?

Your chance to win a Wellcome Media Training Placement with New Scientist

Enter this year’s essay competition and show your skills – it could gain you a career training opportunity

PRIZES FIRST a two-week expenses paid media placement with New Scientist, £1000 spending money and your essay published in New Scientist

The prizewinners plus the 10 runners-up get a free one-year subscription to New Scientist. The prizewinners will be invited to give a short talk at an exciting event to be held in London later this year and to share their work with key players from science and the media

SECOND £750 THIRD £500

Closing date Friday 8 June

For more information and a full list of the competition rules go to www.wellcome.ac.uk/scienceessay 24 | NewScientist | 5 May 2007

Falsifying warming

From Chris Crowe In applying Karl Popper’s philosophy of science, Roger James implies that only a falsifiable hypothesis is a scientific one, and that theories linking such things as greenhouse gas emissions to climate change are “outside science” (14 April, p 23). There are, however, other measures of a theory beyond Popper’s. The science of epidemiology, for example, hypothesises links that cannot be tested in a Popperian framework. It is well accepted that smoking causes lung cancer, despite instances of lung cancer in people who have never smoked, and smokers who never succumb to lung cancer. Legal systems introduce burdens of proof. In British criminal law, conviction requires that defendants be guilty beyond any reasonable doubt; in civil law, issues are decided on the balance of probabilities. Where does climate change sit? Where does smoking sit? There are expert witnesses on both sides, but the preponderance of scientists knowledgeable in these subjects have lined up to say that smoking causes cancer, and man-made greenhouse gas emissions are contributing to climate change. I wouldn’t say that the climate change case is proven beyond a shadow of doubt, but surely it is proven on the balance of probabilities. This level of proof has been sufficient for

governments to exert some control over tobacco companies, and it should now be sufficient for governments to institute controls on climate-affecting industries. Perth, Western Australia From Gregory Bradley The test lies in the name of the phenomenon: “greenhouse effect”. All it would take to falsify it is an experiment conducted under controlled conditions that did not produce a temperature rise resulting from adding accepted greenhouse gases into the atmosphere. In fact, all such experiments have shown a greenhouse effect. In addition, we know humans are releasing large amounts of greenhouse gases; our measurements show levels of greenhouse gases in the atmosphere to be rising; and temperatures are also rising. All these factors tally with the theory being true, so the onus of proof would seem to be on those proposing alternative explanations for the heating to explain why the additional greenhouse gases are not causing it. Man-made greenhouse gas emissions are the simplest explanation for the observed phenomena. Logan, Queensland, Australia From Martin Parkinson Climate scientists are proper scientists; they have heard of falsifiability; there is no growing body of evidence throwing doubt on man-made warming. Bristol, UK

Offset optimism From Dominic Wormell Carbon offsetting seems to me an easy way out for many, letting them avoid addressing the amount of carbon dioxide they produce in their daily lives. I find it hard to believe, however, Fred Pearce’s contention that the planting of trees in a forest restoration programme www.newscientist.com