The start of a US withdrawal process from the Paris climate deal is "very disappointing," Japan's Environment Minister said on Tuesday.
"Creating a decarbonized society is a pressing issue and the US decision is very disappointing," Environment Minister Shinjiro Koizumi told reporters.
"It would be impossible to urge President (Donald) Trump to reverse the decision," Koizumi said.
Cabinet chief secretary Yoshihide Suga also expressed disappointment at the departure from the United States, saying that the international community as a whole must face global warming.
"In view of the declaration of the G20 Summit in Osaka, we will explore ways to cooperate with the United States to address the issue of climate change," the key government spokesman told a news conference.
The United States, the second-largest emitter of carbon dioxide, said on Monday it had formally notified the United Nations of its withdrawal, starting a year-long process to withdraw from the historic pact to combat global warming.
Trump announced his decision in December from 2017 to step out of the pact adopted at a UN climate change conference in Paris, saying it is unfair to his country.
In June, leaders of the 20 economies group in Osaka left a climate change loophole, with the United States reiterating its intention to leave the Paris agreement, while the other members pledged to work towards its full implementation.
The Paris Agreement, successor to the 1997 Kyoto Protocol, aims to keep global temperature rises “well below” 2 ° C in order to limit droughts, floods, melting glaciers, rising sea levels and other results of global warming.