The letter, signed by members of the Biodiversity Institute, the School of Geography and the Environment, and the department of physics, among others, comes as a university-wide consultation on fossil fuel divestment draws to a close.

The consultation was launched following a year of campaigning on behalf of the student-led Fossil Free Campaign.

Among the 64 signatories so far are Lord May of Oxford, former chief scientific adviser to the UK government and Gordon Clark, current director of the Oxford Smith School of Enterprise and the Environment.

Henry Shue, professor of politics and international relations at Oxford, and one of the letter¡¯s signatories, said: ¡°We at Oxford like to claim the mantle of intellectual leadership¡­here is our opportunity to display genuine leadership when it counts.¡±

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Many Oxford students have also backed the proposal, which follows a similar call in April from nearly 100 Harvard University academics who urged their institution via an open letter to remove holdings in oil and coal companies from its $33 billion (?20 billion) endowment.

Brenda Boardman, emeritus fellow at Oxford¡¯s Environmental Change Institute and another of the signatories of the Oxford letter who spoke at a rally on 31 May, said: ¡°We can only burn 20 per cent of the carbon in the proven fossil fuel reserves. We¡¯ll have reached that limit in 16 years at present rates of consumption.

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¡°We know about housing bubbles. Now we have a carbon bubble, a bubble of unreal value. It is too risky to own shares in this bubble. It has to burst and will burst if we are sane and want to avoid dangerous climate change.¡±