US President Donald Trump will withdraw the US from the Paris climate accord, according to reports.
His decision will be made public at 7am (NZ time), but the Associated Press and Reuters both say sources have confirmed he will pull the US out.
Earlier the Vatican, which under Pope Francis' insistence has strongly backed the Paris climate change deal, said the US exit would be a slap in the face and a "disaster for everyone".
At their meeting last month, the Pope gave Mr Trump a signed copy of his 2015 encyclical letter that called for protecting the environment from the effects of climate change and backed scientific evidence that it is caused by human activity.
Vatican Secretary of State Cardinal Pietro Parolin urged Mr Trump in a separate meeting not to quit the Paris accord.
"If he really does [pull out], it would be a huge slap in the face for us," said Bishop Marcelo Sanchez Sorondo, head of the Pontifical Academy of Sciences, which has hosted numerous international conferences on climate change.
"It will be a disaster for everyone," he told the Rome newspaper La Repubblica. In a telephone call with Reuters, Sanchez Sorondo confirmed the comments in the newspaper.
Mr Trump is due to announce his decision around 7am( NZ time).
A source briefed on the decision has told Reuters in Washington that he will follow through on his campaign pledge to leave the global agreement.
Market prepares for US exit
Oil prices rose on Thursday, lifting energy company shares, on expectations the US will withdraw - while China's yuan shrugged off weak factory data to hit a seven-month high against the dollar.
Bank shares underperformed rising European stocks, after two major US lenders warned on Wednesday that low market volatility would crimp trading revenue.
Brent crude, the international benchmark for the oil market, rose off Wednesday's three-week lows in anticipation of the US quitting the Paris accord.
"If he actually withdraws the US from the climate accord, this would signal his intention to further rollback emission regulations that would favour the use and demand of fossil fuels, thus giving a much needed boost to oil prices," said Jonathan Chan, investment analyst at Phillip Futures in Singapore.
A fall in US crude inventories also supported prices. Brent last traded at US$51.39 a barrel, up 64 cents, having touched a low of US$50.31 on Wednesday.
Reuters / Newshub.