Seven shimmering blocks of ice hang from the ceiling of the tunnel between Kunsthaus Zürich's main building and the new extension like icebergs seen floating in the water from below. In fact they are sculpted from white marble and based on scans of pieces of ice that Eliasson and his team collected from a beach on the southern coast of Iceland known as Diamond Beach. The glistening pieces of ice wash up there after breaking off the Breiðamerkurjökull glacier, and remain on shore until they melt away.

Eliasson and his team have made 3D scans of the ice fragments in order to capture the ephemeral forms before they disappear for ever; the data can be used to replicate the ice in a variety of materials. White marble, a favourite material of sculptors since antiquity, was chosen because of its special, luminous quality: light penetrates the surface of the stone for several millimetres before being reflected back by crystals within it.

As a material, marble is often associated with permanence and commemoration. Using the stone to immortalise these ephemeral forms produces a kind of temporal incongruity. Time is also present in the number of blocks: seven for the seven days of the week. And time is of the essence in our struggle to slow down climate change and protect the glaciers.