Prime Minister Theresa May will push world leaders to make a stronger commitment on tackling climate change.
At the G20 summit in Osaka, she will call on them to set targets for net zero greenhouse gas emissions.
Mrs May has also raised the killing of journalist Jamal Khashoggi with Saudi Arabia.
And she pledged more than £1.4bn to help end global Aids, tuberculosis and malaria epidemics.
The UK has enshrined in law a 2050 target to cut greenhouse gas emissions to zero – or in the most difficult cases, to offset them by planting trees or absorbing CO2 out of the atmosphere.
Mrs May is calling for other world leaders to follow suit and wants the summit’s joint statement to have “the strongest wording we can deliver” on climate change.