When the Met Office’s latest £30m supercomputer was switched on in May it drew a fair amount of criticism, and a cloud of suspicion has hung over the organisation’s Exeter-based headquarters ever since. Isn’t it odd, critics asked, that an instrument for combating climate change has such a huge carbon footprint?

Despite the achievements of the UK Met Office, the nation has been characteristically eager to rain on its parade. Much was made of the fact that the new supercomputer uses 1.2 megawatts of energy – enough to power a small town.

With that in mind, it is more powerful than 100,000 PCs – in computing terms, that’s a bargain. The economies of scale achievable mean that the carbon footprint of the Met Office computer is much lower than a town’s worth of desktop machines.

And yet the public finds it difficult to understand why an organisation that is leading the fight against climate change is itself producing 12,000 tonnes of carbon dioxide every year. Perhaps it would help if they knew how many tonnes of carbon dioxide the Met Office’s 400 scientists are helping to prevent from being created as a result of their heightened understanding of global weather conditions.

“The more computing power we have, the better predictions we can make,” says Steve Foreman, the Met Office’s chief technology officer.

We can only save the planet from climate change when we understand it completely – and our full comprehension of the infinitesimal number of variables that determine our weather patterns is a long way from being realised. But the more detailed the Met Office’s study of the planet’s constantly shifting elements becomes, the more accurate our understanding will be.

The Met Office’s systems analysts have divided the planet’s atmosphere into boxes of 20 kilometres in length. The height of the earth’s atmosphere is 70 of these boxes. Within all these boxes, all the variables that make up our weather – pressure, gases, the extent of motion – are measured. In total, there are 300,000 of these points across the globe. Data is collated from hundreds of weather stations, balloons, satellites and atmospheric observations around the world.

Tracking weather variations is a task that requires 1,000 billion calculations every second, which are then fed to the Met Office’s 400 scientists. In this context, given the scope and importance of the work they do, 30 tonnes of CO2 per scientist could seem like a reasonable price to pay if we are to understand the threat of climate change. The scale of the Met Office’s achievements tend to be overshadowed by the fact that it has yet to achieve perfection. Why, the Daily Mail asked, does the Met Office still get the weather forecasts wrong?

If the Met Office is to achieve 100 per cent accuracy, for every square kilometre on the planet, it must step up the thoroughness of its research. This will inevitably call for more calculations, as the earth’s atmosphere is studied in even greater levels of detail than before. Which, as a result, will call for more powerful computing platforms.

Now the Met Office has upped the ante and increased the granularity of its studies.


MET Office CTO Steve Foreman

Under test, it has a new version of its previous model, which lowers the horizontal resolution from 40km to 25km – in the UK only. (Resolution is the distance between points of measurement. Four points are needed to define the patterns of atmospheric variation). The upshot is that eventually each horizontal layer of the earth’s atmosphere will no longer be divided into 300,000 points, but in the near future will consist of 790,000 points.

So the 744 CPUs that make up the Met Office’s IBM supercomputer will be numbercrunching more furiously than ever, the workload will edge ever nearer the machine’s capacity for 145 teraflops and make increasing demands on its 15.5TB of memory.

Add to this, the two giant halls (each the size of two football pitches) that house the supercomputer will draw even vaster resources of electricity from the national grid, and these CPU monsters will need even greater efforts to cool them as they generate 24TB of data every day.

Since the tape robots that store all this data start to suffer at about 23 degrees Centigrade, the heat produced by this system will draw on even more resources for cooling.

Foreman says he is rising to the challenge of lowering the system’s carbon footprint. “We’re looking at more efficient systems of cooling, possibly even free cooling,” he says. Currently, chilled water is used to cool the CPUs, but this system could be replaced when the time for an upgrade arrives.

Another excess that troubles Foreman is the heat that is generated by the CPUs. The Met’s headquarters in Exeter is so economically designed, according to Foreman, that it only ever needs heating for three days each year. So, until they can find a source that needs it, the excess heat generated by the supercomputer will have to be dissipated into the atmosphere.

A more tangible energy-saving device could soon be achieved by tailoring the power supply. “We could use direct current, which would significantly lower the power use,” explains Foreman. “You lose less power than with AC and you get a better rate of power conversion.”

The challenge would be in finding an uninterruptible power supply that works with direct current. Given the scale of the challenges the Met Office has already faced, it should come as no surprise if it were to solve this one.

There are still many riddles and conundrums to be solved before we can predict the British weather, let alone climate change. Some involve the Met Office itself – logically, one would expect the Met Office to be a fan of cloud computing.

However, it is honing its intelligence and advancing to a perfect understanding of the weather.

And when it does, what will we talk about then?