BERLIN (AP) — Swiss environmental activists collected enough signatures to force a referendum on setting specific goals for combating climate change in the country's constitution, authorities said Thursday.

The federal governments said that campaigners submitted more than then necessary 100,000 signatures for the so-called glacier initiative.

Switzerland's famous Alpine glaciers are severely threatened by global warming.

The campaigners want a ban on the sale of all fossil fuels in Switzerland by 2050, with limited exceptions. They are also seeking to cut all net emissions of man-made greenhouse gases by mid-century.

The proposal specifies that any emissions which can't be cut have to be offset by capturing greenhouse gases such as carbon dioxide elsewhere, such as through planting forests or technical means.

The Association for Climate Protection Switzerland, which proposed the referendum and has the support of centrist and left-leaning parties, wants both goals anchored in the Swiss Constitution.

The European Union, which Switzerland is surrounded by but isn't a part of, recently agreed a target of net zero emissions by 2050.