More than 120 Nobel laureates - ahead of the G7 summit - signed a special declaration calling on heads of state and government to step up efforts to combat climate change, DPA reports.

The world runs the risk of far-reaching irreversible changes in the biosphere, the declaration says. The Nobel Prize winners urge heads of state and government to take action to halve greenhouse gas emissions by 2030.

At the end of April, Nobel Prize winners and other scientists, economists, politics, and culture exchanged ideas on actions that can be taken in the current decade to ensure a better future for all.