Intended for healthcare professionals

Analysis And Comment Contraction and convergence

Healthy response to climate change

BMJ 2006; 332 doi: (Published 08 June 2006) Cite this as: BMJ 2006;332:1385
  1. Robin Stott (, vice chair Medact1
  1. 1 London SE10 8JS
  • Accepted 25 April 2006

Environmentally friendly policies may feel like a low priority among the many pressures in a busy professional life, but promoting carbon rationing could be your most important contribution to patients' health

Climate change related to global warming is the world's most urgent public health problem. Our planet is already seriously damaged, with worse to come (box 1).1 Health professionals have an enviable record of contributing solutions to previous threats and must do the same for climate change. The most feasible policy for tackling global warming is contraction and convergence, developed by Aubrey Meyer of the Global Commons Institute.6 So how can health professionals contribute?

Contraction and convergence

Contraction and convergence is a carbon cap and trade policy designed to stabilise and then reduce carbon dioxide emissions, which are responsible for 70% of greenhouse gases. Industrial methane emissions, responsible for much of the rest, will reduce alongside carbon dioxide. Frugal fossil fuel users will be able to sell entitlements to profligate users through international trading of this capped amount of carbon dioxide.

Carbon monoxide plumes show pollution from eastern Asia extending eastward over the Pacific Ocean. Satellite data were collected early in 2003; no data were collected in grey areas because of cloud cover or gaps between viewing swaths


The first step in implementing this policy is to set a global carbon budget and allocate an entitlement of this carbon to each region, country, or person. The initial carbon allocation is then reduced (the carbon budget is contracted) at an agreed pace and time until the amount of allocated carbon equals the globe's carrying capacity, about 12 billion tonnes of carbon dioxide a year. Given the present global population, this amounts to 2 tonnes/person/year, five times less than the present UK average emission.

The effect of contraction is to stabilise …

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