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Surprise, Surprise: Flawed Models Making Fuzzier Climate Picture

The more we know about climate change the more uncertain our models become — and if scientists are not to lose the trust of the public they need to explain this, a senior climatologist has said.

Mark Maslin, a former director of the UCL Environment Institute, was speaking at The Times Cheltenham Science Festival before publication of a commentary in Nature.

He said that the next Intergovernmental Panel on Climate Change report, in 2014, was likely to produce a greater range of projections than the previous one, and that this increasing fuzziness was an inevitable consequence of better calculations.

In one case the uncertainty means that forecasts of the future flow of the Mekong river as a consequence of climate change range from a fall of 16 per cent to a rise of 55 per cent.

However, there was no doubt about the broader outcome, he said. “Increasing our knowledge doesn’t change our story. If you put more greenhouse gases in the model, it gets warmer.”

The reason that the models were becoming less certain in their predictions was because as they improve, it is possible to introduce “known unknowns” such as changes in vegetation growth and reflection from clouds, whose feedback mechanisms were previously too complicated to include.

“The sceptics will jump on this and say, ‘Actually climate change modellers know nothing’,” Professor Maslin said. “I spent six months having a discussion with myself about whether this is something I should write. I believe though, as scientists, we have to be open, honest and transparent.”

Speaking up now would prepare the authors of the IPCC report, who have been notoriously bad at engaging with the public, he said. “It’s a warning shot to say, ‘Guys, guess what? You need to deal with this, and with the media’.”

Professor Maslin said that a challenge was to convey that uncertainty was not a reason for inaction but an inevitability. A key reason was that predictions of fossil fuel use rely heavily on economic predictions, which have been shown to be almost useless.

“I’ve stuck my head above the parapet,” he said. “Considering we are not even sure what the economy will do in the next six months, there are unrealistic expectations that scientists can model the future to any accuracy.

“The introduction of new physics into the model makes some difference to our uncertainty. The biggest uncertainty, though, is what we ourselves do. If we go down a green path, we know our effect on the environment will be reduced. If we go down the business-as-usual route we are looking at extreme consequences. But people seem to like to forget that.”

Joanna Haigh, Professor of Atmospheric Physics at Imperial College London, said: “The top-level conclusion that results will get less rather than more certain I think is wrong. What is happening is the models are pushing the boundaries.

“There is no debate that the climate is changing, that the change is due to greenhouse gas emissions, that greenhouse gas is coming from human activity, and that we need to do something.”

The Festival was also told that wind power is ludicrously expensive, technically primitive and its promotion as a solution to carbon output is a prime reason why China has ignored the low-emissions economy.

John Constable, from the Renewable Energy Foundation, said that the West had failed to provide a viable model for renewable energy power without subsidies. In a debate against the environmentalist Jonathon Porritt and the wind power engineer Andrew Garrad, he said: “Between 2002 and 2011 the UK consumer shelled out £7.3billion in income support for renewable electricity.”

Mr Garrad countered that fossil fuels were also subsidised and wind power was only part of the energy mix.

The Australian, 15 June 2012