World leaders have confirmed their commitment to reducing greenhouse gas emissions after Theresa May urged them to to do more on climate change.
The Prime Minister called on the G20 countries to set targets for net zero greenhouse gas emissions.
The United Kingdom is the first country to legally declare an obligation to be a zero emitter of CO2 by 2050.
At the summit, Mrs May was also one of several world leaders to put pressure on Saudi Arabia during the murder of journalist Jamal Khashoggi last year.
Leader's meeting on climate change called on Mrs May to other world leaders to match Britain's netmind goals for the joint summit statement on "the strongest formulation we can deliver" on the issue.
But only 19 of the 20 leaders endorsed the declaration, which obliged them to "re-irregularize" the Paris agreement in Paris and promised the full implementation of its goals to reduce the greenhouse gas emissions.
US President Donald Trump refused to sign.
Mrs. May said: "In recent months, we have heard hundreds of thousands of young people urge us – their leaders – to act on climate change before it's too late."
The UK's net zero target was "world-leading", she said as she called on other countries to "increase their ambition and embrace this goal".
Britain's goal means that it will have to eliminate greenhouse gas emissions altogether or – in the most difficult cases – offset them by planting trees or absorbing CO2 from the atmosphere.
According to the Paris Agreement, confirmed by the 19 world leaders, all nations are required to keep global temperatures rising to less than 2C (3.6F) higher than before industrial times.
Scientists say a 1.5C increase is the threshold for dangerous climate change, and if other countries adopted the UK's net target, there was a 50-50 chance of staying below 2100.  Human rights issues
a 20-minute meeting with the Saudi Crown Prince Mohammed Bin Salman, she raised the case of the murdered journalist Jamal Khashoggi, a British official said.
The American intelligence ended the Crown Prince killing the Washington Post column of the Saudi Arabian consulate in Turkey last year, but the Saudi authorities have refused to act on his orders.
With 11 unidentified people behind the doors, Ms May Prince Mohammed said the legal process must be "open and transparent," the official said.
Turkish President Recep Tayyip Erdogan said it was Saudi Arabia's responsibility to "uncover" the perpetrators, but added: "Nothing has been done so far." He said they should be prosecuted in Turkey.
Canadian Prime Minister Justin Trudeau also said he highlighted "continuing concerns" about the study and human rights in Saudi Arabia.
But the US President praised Prince Mohammed as a "great federation" and said "no one has so far directly pointed to the future king of Saudi Arabia".
& # 39; Exceptional example & # 39;
Mrs May also invited other countries to follow Britain's 1.4 billion promise. Global Fund, an international organization that combats three of the world's deadly diseases.
The UK will contribute € 467 million. £ a year for three years and provide tuberculosis treatment to over two million people, 90 million mosquito nets to protect people from malaria, and treatment for more than three million people living with HIV – the virus that causes AIDS.
Mrs. May said the world needed "urgent international action and a real collective response" to stop the spread of the disease.
The pledge follows an appeal from Sir Elton John and French President Emmanuel Macron for an 11 billion. cash injection to the Global Fund, which is expected to help save 16 million lives.
Sir Elton, whose helper works with the fund, said the UK's answer was an "extraordinary example for others to follow."
Bill Gates, billionaire philanthropist, one of Global Fund's supporters, said the British pledge was "truly amazing" and called on land to continue supporting overseas aid.
The Microsoft founder told BBC Radio 4's Today program: "I wish all British citizens could go and see how miraculous it is that HIV would kill so many people and really undermine these communities and destabilize them – due to the generosity that has been avoided. "
Tit for tat & # 39;
Earlier in the day, Russian President Vladimir Putin was asked about Mrs May's comments the day before on the Salisbury poisoning and h is claiming that Russia should end its "irresponsible and destabilizing activity".
The United Kingdom believes that two officers from Russia's military intelligence service, GRU, were behind the poisoning of former spy Sergei Skripal and his daughter Yulia in March 2018. Russia denies any involvement.
The Russian president said, "She put her position in a pretty hard way. That's right, that was how it was. I informed her about Russia's position on a number of annoyances in our relationship."
He added: "But people behave for us, we will behave them. Tat tat. I want them to remember it."