For the Met Office the forecast is considerable embarrassment. It has spent £33m on a new supercomputer to calculate how climate change will affect Britain – only to find the new machine has a giant carbon footprint of its own.

“The new supercomputer, which will become operational later this year, will emit 14,400 tonnes of CO2 a year,” said Dave Britton, the Met Office’s chief press officer. This is equivalent to the CO2 emitted by 2,400 homes – generating an average of six tonnes each a year.

The Met Office recently published some of its most drastic predictions for future climate change. It warned: “If no action is taken to curb global warming temperatures are likely to rise by 5.5ºC and could rise as much as 7ºC above pre-industrial levels by 2100. Early and rapid reductions in CO2 emissions are required to avoid significant impacts of climate change.”

However, when it came to buying a new supercomputer, the Met Office decided not to heed its own warnings. The ironic problem was that it needed the extra computing power to improve the accuracy of its own climate predictions as well as its short-term weather forecasting. The machine will also improve its ability to predict extreme events such as fierce localised storms, cloudbursts and so on.

Alan Dickinson, Met Office Director of Science and Technology, said: “We recognise that running such massive computers consumes huge amounts of power and that our actions in weather and climate prediction, like all our actions, have an impact on the environment. We will be taking actions to minimise this impact.”

Dickinson believes, however, that the new computer will actually help Britain cut carbon emissions on a far greater scale than those it emits. He said: “Our next supercomputer will bring an acceleration in action on climate change through climate mitigation and adaptation measures as a consequence of a clearer understanding of risk. Ultimately this will lead to a reduction in greenhouse gas emissions.”

Machines like the Met Office’s new computer are important tools in the battle to slow climate change. They are the only way to assess the potential impact of rising CO2 levels over the coming years and decades.

This is because producing even a short-range weather forecast requires billions of calculations, something that would take weeks to do by hand. Computers enable forecasts to be generated in time to be useful.

Dickinson said: “Our existing supercomputer and its associated hardware produce 10,000 tonnes of CO2 each year, but this is a fraction of the CO2 emissions we save through our work. We estimate that for the European aviation industry alone our forecasts save emissions close to 3m tonnes by improving efficiency.

“Our next supercomputer will bring an acceleration in action on climate change through climate mitigation and adaptation measures as a consequence of a clearer understanding of risk. Ultimately this will lead to a reduction in greenhouse gas emissions.”

When it is finally completed, around 2011 the Met Office machine will be the second most powerful machine in Britain with a total peak performance approaching 1 PetaFlop — equivalent to over 100,000 PCs and over 30 times more powerful than what is in place today.

However, supercomputers and data centres require vast amounts of power – a problem that increasingly confronts the global information technology industry. Last week Google admitted its systems generate 0.2g of CO2 per search, even though each one lasts just 0.2 seconds.

The Met Office in numbers

- performs 125 trillion calculations each second

- £260 million benefit to the UK economy from Met Office forecast

- 74 lives saved a year through our forecasts

- it will make out four-day forecasts as good as our one-day forecasts 30 years ago

- it is the second most powerful supercomputer in the UK

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