Indian Prime Minister Narendra Modi. (J. Scott Applewhite/AP)

AT THE start of Indian Prime Minister Narendra Modi’s trip to the United States, the signals weren’t good that the world’s third-largest emitter of greenhouse gases would change its tone on climate change. In the end, there was a little more room for encouragement .

Mr. Modi, who won a crushing electoral victory in May, declined to attend last month’s United Nations climate summit in New York. When he did address a separate U.N. gathering, he earned the criticism of some observers when he seemed to suggest that practicing yoga is a viable strategy to combat global warming. Meanwhile, Mr. Modi’s environment minister dismissed the notion that India would propose emissions cuts any time soon. “What cuts?” he flippantly exclaimed to the New York Times. All of these moves reflected the stand that India has taken at international climate conferences for years: The country is still developing, so others must put in the hard work to save the atmosphere.

The predominant players on climate change are China and the United States, No. 1 and No. 2, respectively, in the amount of heat-trapping greenhouse gases they release into the air. But India, the world’s second-most-populous country, is ramping up its carbon dioxide output as its government strives to offer 1.2 billion people more reliable electric power. Despite some moves toward renewable energy, about 60 percent of the country’s electrical generating capacity relies on filthy coal burning, and the government appears determined to further develop the nation’s coal industry.

Some forward-looking climate assessments expect relatively little soon from India and conclude that initiatives among other big emitters can still make a huge difference. But more cooperation and a commitment to smarter, more efficient growth on India’s part would make minimizing the risk of climate change much easier — and success much more likely.

That is why we hope the signals Mr. Modi sent on his way out of Washington, following meetings with President Obama, better represent his attitude. He and Mr. Obama pledged to expand several climate initiatives. Top of the list is a U.S.-India partnership on nuclear power that has been held up until now. It would be an authentic accomplishment if Mr. Modi got that back on track, because nuclear reactors produce huge amounts of electricity for near-zero carbon dioxide emissions. Mr. Modi and Mr. Obama also agreed to limit hydrofluorocarbons, powerful greenhouse-gas emissions, through the Montreal Protocol, which is perhaps the most effective environmental treaty ever signed.

Other parts of Mr. Modi’s platform offer some encouragement. He wants to invest more in renewable energy, particularly solar, though still relatively modest amounts. Decarbonizing the country will require rationalizing its chaotic, inefficient energy sector, in which rampant unreliability leads people to use dirty diesel generators to keep the lights on. Mr. Modi made great strides in fixing the grid in his home state of Gujarat. If he can accomplish that for the whole country, and with a wider eye toward sustainability, he will make a significant contribution.