The development is also seen as something that may trigger a clamour within India to de-link itself from China ahead of the make-or-break global climate negotiations in Paris next year.

Climate experts and environmentalists, on the other hand, believe that whatever the top two emitters have pledged is well short of what is needed from them to limit warming to 2 degrees Celsius by the end of the century.

Shyam Saran, former special envoy of the PM on climate change, said, "This agreement was expected. With a declared peak year of 2030, China can continue ?increasing ?its carbon emissions until then, which could be a questionable achievement for climate change.

"India has, in a manner of speaking, already accepted an emissions ceiling. In 2007, then PM Manmohan Singh said India's per capita emission would never exceed the average per capita emission achieved by the developed world. The lower the latter, the ceiling for India too would have to be lower."

A section within the government believes the US-China deal would, by default, give India enough elbow room to peak its emission some 15 or 20 years beyond 2030 - the year around which China promised to reach its peak emission.

It means India may take it easy on its mitigation part and rather focus on adaptation and increasing its share of renewable energy in the country's total energy mix - the stand which the Narendra Modi government may take while de-linking itself from China at international platforms on climate issue.

Commenting on the deal, Sunita Narain, director general of Centre for Science and Environment, said, "It is a self-serving deal in which both countries have agreed to converge their per capita emissions at 12 tonnes in 2030. This is a high level of emission and not in line with meeting the 2 degree Celsius temperature target mandated by IPCC."

She added, "India should push for a principle-based emissions reduction target for all countries. This is the only way we can force the US and China to reduce their emissions which are in line with the planetary limits."

CSE experts believe that India should now work harder with developing countries and push for an ambitious global deal which is equitable and saves the world from catastrophic climate impacts.

Pointing out that the "deal puts a sub-standard benchmark for other countries to follow", CSE's climate expert Chandra Bhushan said, "In the name of getting a consensus in 2015, these two countries are forcing a catastrophic business-as-usual deal on the world. This deal is also a reality check for the government of India about its stance on global climate negotiations. India will have to decide whether it wants to follow the US-China deal or carve out a different path for itself."