A group of scientists in the US and the UK says the accepted wisdom on climate change remains unproved.

They say rising greenhouse gas emissions may not be the main factor in global warming. They argue that temperature rise projections this century are “unknown and unknowable”.

They claim it is “a media myth” to suppose that only a few scientists share their scepticism.

The scientists, a group convened by the American George C. Marshall Institute, first published their report in the US.

‘Political conclusions’

It has been republished in the UK by the European Science and Environment Forum (Esef), entitled Climate Science and Policy: Making the Connection.

Esef says it is “the result of an extensive review by a distinguished group of scientists and public policy experts of the science behind recent findings of the United Nations Intergovernmental Panel on Climate Change (IPCC)”.

The US group included a former CIA director and defence secretary James Schlesinger, and Richard Lindzen, professor of meteorology at Massachusetts Institute of Technology.

The report says the IPCC’s conclusions “have become politicised and fail to convey the underlying uncertainties that are important in policy considerations”.

Its detailed criticisms of the IPCC include:

  • projections of climate change based on models and assumptions which “are not only unknown, but unknowable within ranges relevant for policy-making”
  • models which “do not adequately characterise clouds, water vapour, aerosols, ocean currents and solar effects”
  • a failure “to reproduce the difference in trends between the lower troposphere and surface temperatures over the past 20 years”.

The authors conclude: “The IPCC simulation of surface temperature appears to be little more than a fortuitous bit of curve-fitting rather than any genuine demonstration of human influence on global climate.”

Accused of lying

Philip Stott, emeritus professor of biogeography at the University of London, is a prominent British climate sceptic.

He said: “The authors challenge the key contradiction at the heart of the Kyoto Protocol, the global climate agreement – that climate is one of the most complex systems known, yet that we can manage it by trying to control a small set of factors, namely greenhouse gas emissions. Scientifically, this is not mere uncertainty: it is a lie.”

Professor Stott told BBC News Online: “The problem with a chaotic coupled non-linear system as complex as climate is that you can no more predict successfully the outcome of doing something as of not doing something. Kyoto will not halt climate change. Full stop.”

Eileen Claussen, president of the Pew Center on Global Climate Change, used to work at the State Department and helped to shape US climate policy.

Heavyweight backing

She told BBC News Online: “This report dismisses the findings of the IPCC as alarmist, yet they are widely accepted as representative of the current state of scientific knowledge.

“A panel of the US’s own National Academy of Sciences (which included Richard Lindzen) expressed general agreement with the IPCC’s finding that warming is occurring, and that it is at least partly caused by humans.

“Uncertainty cuts both ways. Some of the IPCC’s scenarios have been criticized as unduly pessimistic, others as unduly optimistic.

“What is important is that they reflect a balance of reasonable futures, and that the scientific findings should be based on the peer-reviewed literature. The IPCC has been able to accomplish exactly that.

“And Kyoto was only intended to be a first step in a long journey.”

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