Postcards calling for action against climate change are stamped in Europe's highest postbox on the Jungfraujoch peak in Switzerland, on March 20, 2019. Some 900 postcards from youths all over the world were stamped and sent on Wednesday from Europe's highest postbox on the Jungfraujoch peak, Switzerland, to global leaders, calling for action against climate change. (Xinhua/Xu Jinquan)
Swiss teenagers Sarangan Sivarajalingam (R) and Selma Schellenberg show copies of a postcard calling for action against climate change on the Aletsch glacier under Jungfraujoch in Switzerland, on March 20, 2019. Some 900 postcards from youths all over the world were stamped and sent on Wednesday from Europe's highest postbox on the Jungfraujoch peak, Switzerland, to global leaders, calling for action against climate change. (Xinhua/Xu Jinq
Copies of a postcard calling for action against climate change are seen on the Aletsch glacier under Jungfraujoch in Switzerland, on March 20, 2019. Some 900 postcards from youths all over the world were stamped and sent on Wednesday from Europe's highest postbox on the Jungfraujoch peak, Switzerland, to global leaders, calling for action against climate change. (Xinhua/Xu Jinquan)
Swiss teenager Sarangan Sivarajalingam shows a copy of a postcard calling for action against climate change on the Aletsch glacier under Jungfraujoch in Switzerland, on March 20, 2019. Some 900 postcards from youths all over the world were stamped and sent on Wednesday from Europe's highest postbox on the Jungfraujoch peak, Switzerland, to global leaders, calling for action against climate change. (Xinhua/Xu Jinquan)
Swiss teenager Selma Schellenberg shows a copy of a postcard calling for action against climate change on the Aletsch glacier under Jungfraujoch in Switzerland, on March 20, 2019. Some 900 postcards from youths all over the world were stamped and sent on Wednesday from Europe's highest postbox on the Jungfraujoch peak, Switzerland, to global leaders, calling for action against climate change. (Xinhua/Xu Jinquan)