The Cop26 climate talks have been postponed until 2021 - pushing back the summit which would have put the UK centre stage in the global fight against climate change.
The UN event, used to plan global answers to rising global temperatures, biodiversity loss and other environmental matters threatening the planet, was due to be hosted in Glasgow in November.
The summit has become a focal point for geopolitical answers to the issue of climate change - with the Paris Climate Accord among its legacies.
Announcing the postponement, Cop26 president-designate and UK Business and Energy Secretary Alok Sharma said: "The world is currently facing an unprecedented global challenge and countries are rightly focusing their efforts on saving lives and fighting Covid-19.
"That is why we have decided to reschedule Cop26.
"We will continue working tirelessly with our partners to deliver the ambition needed to tackle the climate crisis and I look forward to agreeing a new date for the conference."
UN climate change chief Patricia Espinosa said: "Covid-19 is the most urgent threat facing humanity today, but we cannot forget that climate change is the biggest threat facing humanity over the long term.
"Soon, economies will restart. This is a chance for nations to recover better, to include the most vulnerable in those plans, and a chance to shape the 21st century economy in ways that are clean, green, healthy, just, safe and more resilient.
"In the meantime, we continue to support and to urge nations to significantly boost climate ambition in line with the Paris Agreement."