The Edinburgh International Science Festival is in town and its artistic arm - for it has recently sprouted one - is to be found at Summerhall, the art complex housed, appropriately in this context, in the building that used to be Edinburgh University's Royal Dick Veterinary School.

"We've had a few Science Festival events here before," says Summerhall curator, artist and, incidentally, former scientist Paul Robertson, "but this year we've effectively become the second arm of the Festival after the City Art Centre."

With this new venture, curated by Robertson, the expanded festival, which this year seems to be popping up in more venues around the city than ever, now has a cutting-edge artistic strand that reflects the cutting-edge science elsewhere in the programme.

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The most intriguing in a series of exhibitions which range from the international to the domestic - a balance of which Summerhall itself, run along the 'kunsthalle' model, tries to keep during the rest of the year - is the weather-inspired installation from Swedish duo Bigert and Bergstrom. While downstairs British artist David Burrows has plumped for recreating a black hole - with a lot of blue spangles - in Summerhall's Library, the Swedes have rolled up their sleeves to grapple with a phenomenon of rather more human-scale destructive nature.

The Weather War is an exhibition with its roots in the 'tornado belt' of the southern United States. Bigert and Bergstrom, whom Robertson jokingly refers to as "the Gilbert and George of Sweden", joined Canadian storm chaser and meteorologist Mark Robinson on a journey into America's Midwest to document increasingly hostile weather patterns while attempting to change the course of the weather itself with their own somewhat megalomaniacal-sounding 'Tornado Diverter' machine. If it sounds dangerous, it was, although perhaps not for the reasons one might think. "The artists told me that storm chasing is apparently so popular now that one of the most dangerous things about it is that there are so many people chasing after the tornadoes that you are likely to crash," laughs Robertson.

The Tornado Diverter itself, which looks a little like something out of a sci-fi B-movie, is based on the research of scientist Vladimir Pudov, formerly of the Russian Institute of Experimental Meteorology in Obninsk, whose ideas on diverting tornadoes intrigued the Swedish artists to such an extent that they decided to build his machine - which he did not have the funds to develop - for him. "Does it work?" says Robertson. "Well, once we've had it here a few weeks and we've had no tornadoes, I'll be able to say it does!"

Robertson discovered Bigert and Bergstrom after a conversation with the German agent, Barbara Strumm, with whom he had worked previously. "I told her I was looking for artists whose inspiration was primarily scientific, and she pointed me in their direction. And I have to say I was really surprised they were not better known here."

After much toing and froing, an articulated lorry from Berlin arrived at Summerhall last week with the duo's installation. The centrepiece is the hour-long "hugely entertaining" film charting the pair's storm-diverting quest. Around it are sculptural installations extracted from the film, from a huge black ball entitled The Problem (seen being pushed around Midwestern fields in the film) to the Tornado Diverter itself.

And Biggert and Bergstrom are serious in their work. "In some ways they are as much artists as activists," says Robertson.

"Their work is not just about an interesting aesthetic experience but suggests that people take action. In the United States there is a large degree of climate change denial despite overwhelming evidence that climate change is caused by human intervention. Bigert and Bergstrom's work reminds the world that we need to be careful about what we do, and not just let ignorance take over."

The Weather War, Upper Church Gallery, Summerhall, Edinburgh (0845 874 3000, until May 24