Church leaders are urging leaders to commit to radical action to save the planet from climate catastrophe.
The warning comes as the UN's COP26 climate summit gets underway in Glasgow, Scotland.
The Archbishop of Canterbury, Justin Welby, told the Evening Standard that the outcome of the talks would mean "life or death for millions of people".
He said it was his hope that the voices of communities already affected by climate change and those on the "burning front lines of climate injustice" would be heard.
The Archbishop said urgent action was needed to "save our world from the worst of the catastrophe", and that world leaders needed to understand the seriousness of the situation.
"The COP26 climate talks are emergency surgery for our world and its people," he said.
"The outcome will be life or death for millions of people. That's how seriously we must take this moment.
"The eyes of the world are on Glasgow: leaders must deliver for the whole human family. We can, and must, choose life, so that our children may live."
The Church of England this week launched a consultation on achieving net zero emissions across its parishes by 2030.
It has already divested from coal companies, with plans to do the same from the oil and gas sector by 2023.
The Archbishop continued, "If these talks do not deliver, we face a dark, disturbing future – but there is still time, just, to save our world from the worst of the catastrophe.
"This is a chance to start living in a way that is healthier, kinder, and better for everyone."
Pope Francis made a similar plea in a special message recorded for BBC Radio 4's Thought for the Day ahead of the summit.
"Climate change and the Covid-19 pandemic have exposed our deep vulnerability and raised numerous doubts and concerns about our economic systems and the way we organise our societies," he said.
"We have lost our sense of security, and are experiencing a sense of powerlessness and loss of control over our lives. We find ourselves increasingly frail and even fearful."
