British Prime Minister Boris Johnson urged climate negotiators to do whatever was necessary to seal a deal at COP26, ahead of a trip to the Glasgow summit to hear what progress has been made.
"There's still much to do," Johnson said in a statement on Tuesday before his departure from London. "This is bigger than any one country and it is time for nations to put aside differences and come together for our planet and our people."
The United Nations event is billed by leaders as a pivotal moment in which governments around the world must agree new ways of cutting carbon emissions to prevent global temperatures rising too far and to limit the worst effects of climate change.
The talks have so far seen high-profile announcements that if enacted will go some way - but not far enough - to limiting the temperature rise to 1.5 Celsius.
"We need to pull out all the stops if we're going to keep 1.5C within our grasp," Britain's Prime Minister added.
Several major issues remain unsolved in the backroom negotiations over how to implement the aspirational climate goals set down in the 2015 Paris Agreement.
Scientists say 1.5C, the goal agreed in Paris, is the most the Earth can afford to avoid a catastrophic rise in intense heatwaves, droughts, storms, floods and crop failures.
Johnson's office highlighted key issues like how often countries should revise and improve their emissions-cutting plans, common reporting standards, and finance to help the most vulnerable nations cope with climate damage.
Together with U.N. Secretary General Antonio Guterres, Johnson will meet representatives from national negotiating teams and groups representing civil society.
Britain's Alok Sharma, a member of Johnson's government and president of COP26, earlier told reporters that while progress was being made, there was still "a mountain to climb" in the remaining three days of the summit.