A global agreement on climate change is set to win enough ratifications by signatory nations this week to go into force in November, heralding a harder phase of turning promises into cuts in greenhouse gas emissions.
The 2015 Paris Agreement, outlining a shift from fossil fuels this century, says efforts to oversee compliance will be "non-adversarial and non-punitive", raising questions about how to ensure governments pull their weight.
The European Parliament is set to give the green light on Tuesday for European Union states to join up this week, tipping the accord past a threshold of nations accounting for 55 percent of world emissions to enter into force.
So far, the 2015 Agreement has backing from 62 countries responsible for 52 percent of emissions, after India approved it on Sunday. Once it reaches 55 percent, it will enter into force in 30 days.
"The key question will be implementing the agreement. There's no legal enforcement of pledges," said Robert Watson, a British-American scientist and former head of the U.N.'s panel of climate experts.
The hope is governments will feel a "moral obligation" and "peer pressure" to act, he told Reuters.
Under the Paris Agreement, almost 200 states have set their own national targets for emissions, with five-yearly national reviews and promises to set ever tougher goals.
David Waskow, of the World Resources Institute think-tank, said the rapid ratification was a sign of willingness to tackle emissions, blamed for heatwaves, floods, downpours and a rise in ocean levels.
The Paris Agreement aims to limit a rise in world temperatures to "well below" 2 degrees Celsius (3.6 Fahrenheit) above those in pre-industrial times. The United Nations says current pledges are too weak to reach that goal.
The agreement is likely to enter into force before the U.S. presidential election on November 8. Republican nominee Donald Trump opposes the deal, while Democrat Hillary Clinton is a strong supporter.
It would also enter into force before an annual meeting of environment ministers in Marrakesh, Morocco, next month, which is expected to work on the nuts and bolts of the deal.
"Marrakesh will be more of a 'roll up your sleeves' working (meeting) than a big set of ground-breaking decisions," said Jake Schmidt, of the U.S. National Resources Defense Council. (Reuters)