The United States, Britain and the European Union have set a target date of 2050 to reach net zero, by which point they will only emit an amount of greenhouse gases that can be absorbed by forests, crops, soils and still-embryonic carbon capture technology.

China and Saudi Arabia have both set targets of 2060, but these are largely meaningless without tangible action now, critics say.

Between now and the middle of the century the United States will release 92 gigatons of carbon into the atmosphere and the EU 62 gigatons, Gupta said, citing Indian government calculations. China would have added a staggering 450 gigatons by its net zero target date, he added.

Representatives of nearly 200 countries will meet in Glasgow, Scotland, from October 31- November 12 for climate talks to strengthen action to tackle global warming under the 2015 Paris Agreement.

Indian Prime Minister Narendra Modi will attend the conference in a sign of how the country is taking climate change seriously, officials say. Chinese President Xi Jinping is not expected.

While working towards net zero, countries are expected to announce new and strengthened intermediate targets for cutting emissions.

Environment Minister Bhupendra Yadav said India was on track to achieve targets set at the 2015 Paris conference and left the door open to revising them. "All options are on the table," he said.

India has committed to cutting the emissions intensity of its GDP by 33%-35% by 2030 from 2005 levels, achieving a 24% reduction by 2016.

Some environment experts say India could consider lowering its emissions intensity by as much as 40 percent dependent on finance and whether it has access to newer technologies.

Yadav said he would measure the success of the Glasgow conference by how much it delivered on climate finance to help the developing world cut their emissions while ensuring economic growth.

"We can't do it on our own as we need to think about our economy as well," he said.

But Yadav made it clear that India would not be pressured to do more to cut emissions, when developed nations were not meeting their own climate targets.

Coal is the dirtiest form of energy and scientists say phasing out the use of coal is key to tackling the climate crisis. But more than 70% of India's electricity is still generated by coal-fired thermal power plants.

Yadav said it was not reasonable for India to drastically cut coal production and "even developed countries are taking time to exit coal and gas sectors."

Even with India's growing energy needs to accommodate its 1.3 billion population, environment secretary Gupta said, "the share of energy from coal and installed capacity in percentage terms will keep reducing."

This, in part, will come from retiring and decommissioning old and inefficient power plants, even as new ones are being built, Gupta said.

"Forcing a sectoral agenda is not good. We will (take a call on coal production) at our own pace," he added.