US climate envoy John Kerry on Tuesday pressed India, the world's third-biggest carbon emitter, to set more ambitious green goals ahead of UN talks in late 2021 and Joe Biden's upcoming climate summit.

A spokesperson for the US embassy in New Delhi, where Kerry arrived on Tuesday for talks with officials and NGOs, said that India was a "critical part of the solution to the climate crisis."

Bloomberg News reported last month that top Indian government officials were debating whether to follow dozens of other countries in setting a goal of net zero emissions by mid-century.

When Kerry's April trip to the United Arab Emirates, India and Bangladesh was announced, Washington said the aim was "increasing climate ambition" ahead of President Biden's April 22-23 summit and the UN negotiations in Glasgow in November.

"A key focus for our administration is supporting and encouraging India's decarbonization efforts through clean, zero, and low-carbon investment, and supporting India in mitigating its fossil energy use," the US spokesperson said on Tuesday.

India may however baulk at setting a zero-emissions target, because that would require a major overhaul of its heavily coal-dependent economy -- and because it has already set ambitious renewable energy goals.

India wants to expand renewable power to 450 gigawatts by 2030, almost five times existing capacity, and to cut emissions intensity by at least a third from 2005 levels by the end of the decade, according to Bloomberg News.

India and other poorer countries also want richer nations to do the heavier lifting in reducing global emissions, saying that many of the latter have considerably bigger per-capita rates and are historically more responsible for global warming.

The White House has said that the United States will announce an "ambitious 2030 emissions target" ahead of this month's virtual summit of 40 leaders, including Indian Prime Minister Narendra Modi and Chinese President Xi Jinping.

Biden in his invitation "urged leaders to use the Summit as an opportunity to outline how their countries also will contribute to stronger climate ambition," the White House said.

The Paris Agreement left countries in charge of making their own promises and taking their own measurements of emission reductions, but requires them to regularly revise their Nationally Determined Contributions.

The agreement's goal is to limit the increase in global temperatures by the end of the century to around 1.5 degrees Celsius above pre-industrial levels -- or risk leaving much of the planet inhospitable to life.