President Joe Biden has invited his counterparts Xi Jinping of China and Russia's Vladimir Putin to a virtual climate summit he is hosting in April, the White House announced on Friday.

In all, 40 world leaders have been asked to attend the two-day meeting meant to mark Washington's return to the front lines of the fight against man-made climate change, after former president Donald Trump disengaged from the process.

"They know they're invited," Biden said of Xi and Putin. "But I haven't spoken to either one of them yet." 

The start of the summit on April 22 coincides with Earth Day, and will come ahead of a major UN meeting on climate change scheduled for November in Glasgow, Scotland.

It is being staged entirely online due to the coronavirus pandemic.

Biden kept his campaign pledge to rejoin the Paris climate agreement on his first day in the White House, after Trump pulled out of the deal.

The return of the world's largest economy and second-largest emitter of carbon dioxide became effective on February 19, and means almost all the world's nations are now parties to the agreement signed in 2015.

By the time of the summit, the US will have announced "an ambitious 2030 emissions target," according to a White House statement, and will encourage others to boost their own goals under the Paris agreement too.

"The Summit will also highlight examples of how enhanced climate ambition will create good paying jobs, advance innovative technologies, and help vulnerable countries adapt to climate impacts," the White House said in a statement.

The United States has invited the leaders of the Major Economies Forum on Energy and Climate, which includes the 17 countries responsible for about 80 percent of global emissions and GDP, as well as heads of countries that are especially vulnerable to climate impacts or are demonstrating strong climate leadership.

The US president has placed global warming at the heart of his agenda, and has already made waves domestically by pledging to make the energy sector emissions neutral by 2035, followed by the economy as a whole by 2050.

He has also placed a hold on new oil and gas drilling on federal lands and offshore, and is expected to soon seek a $2 trillion infrastructure package from Congress that would serve as the engine of future economic growth.

Biden dispatched his climate envoy, former secretary of state John Kerry, to prepare the ground for the summit in meetings with European leaders earlier this month. 

The meeting comes as the world is lagging badly in its efforts to limit end-of-century warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit), which scientists say is necessary to avoid triggering climate tipping points that would leave much of the planet inhospitable.

In an assessment of pledges made in recent months by around 75 countries and the European Union, UN Climate Change said that only around 30 percent of global emissions were covered in the commitments.