Church leaders have written to the Prime Minister urging him to commit to a 75 per cent reduction in UK carbon emissions by 2030.
The Church of England's lead bishop for the environment, Bishop Nicholas Holtam, the Archbishop of Wales, and leaders in the Church of Scotland, Baptist Union, Methodist Church and United Reformed Church are among the signatories.
The call comes ahead of the UK's submission of its first climate plan under the Paris Agreement, and before the nation hosts the next UN climate summit in Glasgow in just under a year from now.
"In 2021, the UK has the chance to be a true global leader. 2021 is a critical year to tackle the climate crisis and the UK is uniquely placed to lead the world in ambitious action as the President of the COP26 UN climate talks," the Church leaders write.
In addition to emissions cuts, they want to see greater support for countries at risk of the negative effects of climate change, including financial assistance and help to adopt renewable energy technology instead of fossil fuels.
"As we look with hope to the securing of a critical deal in Glasgow next year, churches across the UK are committed - together with Christian Aid and its supporters - to working with you and your Government to help deliver a national climate plan that ensures climate justice for the world's poorest people," they conclude.
The letter echoes the call of a Christian Aid petition calling for tougher action to reduce carbon emissions, which has been signed by 57,000 people.
Pete Moorey, Christian Aid's Head of Campaigns and UK Advocacy said: "The climate emergency is the great moral issue of our time. The people suffering the most are those that have done the least to cause it.
"That's why church leaders from across Britain have stood together to call on Boris Johnson to set a bold commitment for other countries to follow.
"As president of the UN climate summit next year, the UK will be encouraging other nations to come forward with ambitious plans. The UK's own climate pledge must set a high bar for action, anything else would be a failure of leadership.
"After the recent decision to cut UK overseas aid, the UK has a moral duty to make inequality and injustice in the world's poorest countries central to next year's summit. People around the world facing the reality of climate change right now are counting on it to be a success."
