Climate and health debate

The World Health Organisation estimates that 150,000 deaths each year can be attributed to the effects of climate. Will this figure rise as a result of global warming? What do we know about the likely effect of climate change on our health? And how should we manage new risks?

So goes an introduction to three articles on climate and health prefacing a live debate in London on 8 March.

The articles are worth reading for the contrast in thinking they display and the way they rehearse issues, or claims, that are not always well spelt out.

 Myles Allen of the Climate Dynamics Group at the  University of Oxford  writes:

Tougher tests are required before we can conclude that greenhouse gas emissions are killing people. The signal may just now be becoming strong enough for these tougher tests to be passed, but it is crucial for the credibility of the whole science of attribution that we don't blow the whistle too early.

Nevertheless, he says, there are no grounds for complacency:

For example, the heatwave in the summer of 2003 is estimated to have caused between 20,000 and 30,000 'excess deaths' (above what would be expected in a typical August) across Europe. The epidemiological evidence is reasonably clear, and there was no marked decrease in mortality following the heatwave, so these were not deaths due to a simple 'harvesting' effect that were brought forward by only a few weeks: many of the victims would otherwise have survived for years. In a paper published in December 2004, we argued that past human influence on climate is likely to have increased the risk of such a heatwave by at least a factor of two, more likely a factor of four or more.

Joe Kaplinsky, a science writer, does not take account of Allen’s argument, but makes the case that climate change has only marginal impacts which can be better dealt with as societies develop, and that spending is better directed  to  aggressive health  promotion programmes in poor and vulnerable countries than reducing greenhouse gas emissions.

Benny Peiser, of the faculty of science at Liverpool John Moores University, says  it is cold that kills:

 more than 100,000 people die on average each year as a result of cold temperatures during the winter months… A warming of 2.5 degree Celsius would lower the annual death rate by 40,000 in the USA alone while reducing medical costs by almost $20bn per year.

Allen looks to have a stronger, if more cautious, opening position for the debate (incidentally, his article The blame game is worth reading. A striking combination of scientific and legal thinking co-written with the lawyer Richard Lord, it notes that English law takes a more flexible approach to questions of causation, with a 2002 case in the House of Lords (Fairchild v. Glenhaven) suggesting that "material increase in risk" may sometimes be an appropriate test).

Kaplinsky and Peiser may have chosen their ground less carefully. Not least, they don’t appear to have fully taken account of the way climate change – more accurately climate instability – may have multiple effects that will be hard to manage and could cause increased mortality in numerous ways. A good place to start on this is www.stabilisation2005.com

 The live debate takes place at IBM South Bank, 76 Upper Ground, London SE1 9PZ from 6.30 on  8 March (with Paul Wilkinson of the London School of Hygiene and Tropical Medicine joining Allen and Kaplinsky in place of Peiser).