The United States will press all nations to reduce reliance on coal, Secretary of State Antony Blinken said Monday, in an implicit challenge to China as he vowed greater US leadership.

Blinken kicked off a week of intense climate diplomacy by President Joe Biden, who has invited 40 world leaders to a virtual summit Thursday and Friday aimed at raising the world's ambitions on climate.

Casting climate change as a national security issue, Blinken warned both of major impact around the planet -- and risks to the United States if it does not raise its own efforts.

"It's difficult to imagine the United States winning long-term strategic competition with China if we cannot lead the renewable energy revolution," Blinken said in a speech in Annapolis, Maryland.

"Right now, we're falling behind."

While Blinken pointed to China's lead on solar and other technology, the Asian power is also the world's largest emitter of carbon blamed for climate change -- and by far the biggest user of coal, the dirtiest form of energy.

"Our diplomats will challenge the practices of countries whose action -- or inaction -- is setting us back," Blinken said.

"When countries continue to rely on coal for a significant amount of their energy, or invest in new coal factories, or allow for massive deforestation, they will hear from the United States and our partners about how harmful these actions are."

China, despite a pledge to go carbon neutral by 2060, has moved ahead with coal-powered plants, only modestly increasing ambitions for renewables in its latest five-year development plan.

Coal is also a sensitive issue in the United States which under former president Donald Trump left the Paris climate accord as he declared himself a champion of miners, although demand for coal has kept falling.

- Not 'much of a world left' -

In the speech punctuated by chirping birds in front of Chesapeake Bay -- which Blinken noted was sinking -- the top US diplomat said the United States did not see climate just "through the prism of threats."

"If America fails to lead the world on addressing the climate crisis, we won't have much of a world left," Blinken said.

"If we succeed, we will capitalize on the greatest opportunity to create quality jobs in generations; we'll build a more equitable, healthy, and sustainable society; and we'll protect this magnificent planet."

Biden has proposed a massive $2 trillion infrastructure package that includes a major transition toward green energy.

He is expected to announce a more ambitious US target on reducing carbon emissions by 2030 ahead of the summit.

Blinken also tied the impact of climate change to migration from Central America -- an increasingly fraught issue for Biden -- and greater competition in the Arctic as ice melts and waterways open.

Blinken pointed to the increased activity of China and especially Russia in the Arctic.

"Russia is exploiting this change to try to exert control over new space," Blinken said.

Blinken confirmed he would participate in a meeting next week in Iceland of the Arctic Council.

The gathering could mark the first occasion for Blinken to meet Russian Foreign Minister Sergei Lavrov amid myriad tensions between the two powers, including sanctions imposed last week by the United States over alleged election interference and hacking by Moscow.

UN Secretary-General Antonio Guterres also urged strong action on climate Monday, saying the world was "on the verge of the abyss" with 2020 yet another of the hottest years on record despite a pandemic-related slowdown.