G20 nations produce half the world's plastic waste, and Japanese Prime Minister Shinzo Abe, who will chair the summit, has made fixing the problem a top initiative, both at the summit and in Japan.
Trade and geopolitical tensions, and the looming threat of climate change, are on the agenda as Chinese President Xi Jinping and other world leaders gather in Osaka, Japan, for a summit of the Group of 20 major economies.
While prospects for detente in the trade war between the United States and China are in the spotlight, many participating are calling for a broader perspective in tackling many global crises.
Chinese President Xi Jinping, Turkish President Recep Tayyip Erdogan and other world leaders were arriving in Osaka on Thursday.
"This will be a difficult G-20, there are global challenges to be met, we need to step up to avoid the climate threats, ... reform the World Trade Organization and prepare for the digital revolution," Donald Tusk, president of the European Union Council, said at a meeting with Japanese Prime Minister Shinzo Abe.
The summit comes at a time of growing international tensions, for example, over Iran's nuclear deal, as well as disputes between the United States and China over trade and technology.
President Donald Trump was due to arrive later Thursday and to meet with Xi on Saturday as the G-20 meetings conclude.
A Chinese Foreign Ministry spokesman in Beijing said China intends to defend itself against further US moves to penalize it due to trade friction.
Threats by President Donald Trump to impose more tariffs on Chinese exports "won't work on us because the Chinese people don't believe in heresy and are not afraid of pressure," said Geng Shuang.
China has sought to gain support for defending global trade agreements against Trump's "America First" stance in gatherings like the G-20.
Climate change on top
Naoyuki Yoshino, Dean of the Asian Development Bank Institute, said hopes were high leaders would tackle climate change policies.
Japan is expected to put the tackling of plastic marine waste high on the agenda.
Japan is the world's Number 2 consumer of single-use plastic packaging per person — the United States is Number 1 — according to a 2018 UN Environment Program report.
G20 nations produce half the world's plastic waste, and Abe, who will chair the summit, has made fixing the problem a top initiative, both at the summit and in Japan.
Abe has sought to make the Osaka summit a landmark for progress on environmental issues, including climate change. French President Emmanuel Macron reinforced that message on Wednesday during a state visit to Tokyo, where he described climate change as a "red line" issue for endorsing a G-20 communique.
"It's the moment to be truly in time in the face of history and to fulfil our responsibility," Macron said. "I will not sign if we don't go further in our ambition about climate change. That would mean all those summits are for nothing."
'No coal Japan'
On the periphery of the Osaka meetings, activists belonging to a coalition of 50 environmental groups protested outside a coal-fired power plant in the nearby port city of Kobe.
They chanted "No coal Japan!" while raising an inflatable depicting Abe, taking aim at his efforts to promote such projects across the globe. They also want more aggressive efforts by the Japanese government to help curb climate change.
Japan is one of the largest funders of coal-fired power stations overseas, having ramped up their use inside the country after most nuclear power plants were idled following the 2011 nuclear disaster in Fukushima. The effort to offset the loss of the generating capacity has slowed Japan's own progress in curbing the carbon emissions that contribute to global warming.
"We made this balloon and organised this protest to make him feel embarrassed, have him feel the pressure inside and outside Japan," said Hanna Song of the Japan Center for a Sustainable Environment and Society.
"We want him to stop funding coal and not to make climate change worse."
Trips and talks
Xi was also expected to hold talks with Abe, seeking a breakthrough after years of strain over territorial disputes.
It is his first visit to Japan since he became the head of communist-ruled China in 2013.
A visit by Xi to North Korea last week raised hopes for some movement in the impasse with the US over the North's nuclear program.
Trump also is due to visit South Korea after leaving Japan, raising speculation there may be more news on Korean issues during his Asian travels.
Trump has at times found himself at odds with other leaders in such international events, particularly on issues such as Iran, climate change and trade.
The leaders, arriving steadily throughout the day under heavy monsoon rains, were well insulated from such protests by the security blanketing Osaka, a business centre of 2.7 million in western Japan.
The authorities closed roads and brought in platoons of extra police