Maintaining that US' response to climate change is "disappointing", environment minister Jairam Ramesh on Sunday appealed America to better its emission reduce commitment before it was too late for the global community.

Ramesh expressed deep concern about the US offer to reduce carbon emissions by 17 per cent from 2005 levels by 2020, which he said worked out to a 4 per cent reduction on 1990 reference level used by Kyoto Protocol parties.

He further said that due to absence of domestic legislation, executive action could only achieve 14 per cent reduction by 2020 on 2005 level, which translates to zero per cent reduction of carbon emissions on 1990 levels.

"By any standard the US offer on emission reduction for 2020 is deeply disappointing," he said. "It's one thing being ambitious for 2050 when all of us will be dead but the real issue is... are you going to be held accountable for 2020 mid term targets are very essential."

Under the US plan, it will reduce its carbon emissions by 80 per cent from 2005 levels by 2050.

"We would certainly expect the United States to better its emission reduce commitment as well as its offer on finance-start finance," Ramesh said, pointing out that the offer of USD 1.7 billion, which he said "did no justice to the world's preeminent economic power."

Meanwhile, Todd Stern, the US envoy to the UN, said that his country could only implement its 17 per cent pledge with a "legislative component."

Stern also expressed confidence that a mix and match of options would allow the US to fulfill its climate obligations even without comprehensive legislation in the US.

"President Barack Obama has made it very clear that there is more than one way to skin a cat... a combination of regulatory and legislative tools that will be at our disposable will get us there," he said.

Ramesh, however, said no climate change treaty was possible without having the US on board since it was the largest pre capita emitter of greenhouse gases and also the country, which could provide the most finance and technology to combat climate change.

"To have an international agreement without the United States makes no sense," he said. "It remains the innovation engine of the world to provide technology support for both adaptation and mitigation.