A White House official said the US would cut emissions by 50 to 52 percent compared with 2005 levels.
Taking place on Earth Day, the US-hosted event brings together 40 countries – including major polluters China and India – with some two dozens leaders set to deliver speeches.
US President Joe Biden is looking to reassert his country’s role as a leader on climate action after four years Donald Trump’s “America first” approach.
The two-day summit begins a day after the European Union reached a breakthrough deal for a climate law to reduce emissions by “at least 55 percent” by 2030.
It also comes after the United Kingdom – host of the upcoming United Nations Climate Conference – ramped up its emissions-cutting ambition to 78 percent by 2035.
Off-target
Scientists say major polluters must be carbon neutral by the middle of the century in order to meet the Paris Agreement goal of limiting warming to "well below" 2 degrees Celsius.
However the world’s three biggest carbon emitters – the US, China and India – have yet to update their national contributions to achieve this. Based on existing pledges, the world is heading for global warming of about 3 degrees.
Along with Biden, Chinese President Xi Jinping, Indian Prime Minister Narendra Modi and French President Emmanuel Macron are scheduled to speak at the summit.
Renewed national pledges will lay the groundwork for November's Cop26 conference in Glasgow, which has been delayed by the coronavirus pandemic.
