Switzerland’s Aletsch Glacier – which can be seen from space – is losing up to 12 meters of ice every year, shrinking so fast that glaciology experts warn it could disappear entirely by the end of the century. That’s why it’s the site for a new project raising awareness about climate change: more specifically, a giant postcard.

The Swiss government's Agency for Development and Cooperation (SDC), in collaboration with the Wave Foundation, organised the collection of postcards with messages opposing climate change sent from children from across the world. Then, they attached them together to make one massive postcard – measuring 2,500 square meters – that they laid out on the shrinking glacier at an altitude of 3,400 meters.

The intention of the apparent biggest postcard in the world is to, “boost a global youth climate movement ahead of the next global climate conference (COP24) in Poland,” say the Wave Foundation.

Assembled, the postcard spells out messages such as “Stop Global Warming” and “#1.5C”. The latter is a reference to a UN report, released last month, that suggests we need to limit the planet’s temperature rise to 1.5°C (down from the 2°C proposed at the 2015 Paris climate talks).

“Children and young people have a key role to play if (the 1.5C) goal is to be achieved, both as generations that will suffer from the consequences of climate change for a long time and as a force for concrete action,” the SDC explain.