Artist Olafur Eliasson has “constructed a reversed waterfall in which the water shoots up rather than down; a massive disc which loomed low over the city of Malmo in Sweden, lit at night by yellow light so that it resembled a night-time sun; and a long, snaking slick of green dye in the waterways of Stockholm.” Now he’s taken on creating something for the giant turbine room at Tate Modern, which he hopes to tunr into a “microclimate.”