Global security and stability could break down, with migration crises and food shortages bringing conflict and chaos, if countries fail to tackle greenhouse gas emissions, the UN’s top climate official has warned ahead of the Cop26 climate summit.

Patricia Espinosa, executive secretary of the UN Framework Convention on Climate Change, said: “We’re really talking about preserving the stability of countries, preserving the institutions that we have built over so many years, preserving the best goals that our countries have put together. The catastrophic scenario would indicate that we would have massive flows of displaced people.”

The impact would cascade, she said, adding: “It would mean less food, so probably a crisis in food security. It would leave a lot more people vulnerable to terrible situations, terrorist groups and violent groups. It would mean a lot of sources of instability.”