A big climate announcement could come this week in Washington.
Experts are watching to see if Indian Prime Minister Narendra Modi commits to ratifying the Paris climate agreement before the end of the year. If India ratifies the deal, that will put it on the brink of going into force well ahead of the original 2020 target.
Advocates say it would be a strong signal that developing countries are serious about fighting climate change. But critics note that India has committed to very little under the Paris agreement. They say much more will be needed from India and the rest of the world to keep the planet below the 2-degree threshold that scientists consider critical to the well-being of the planet.
Modi is on a state visit to the United States, including a special address to a joint meeting of Congress and his seventh meeting with President Obama.
The two leaders "really have a meeting of the minds" on climate change and clean energy, says World Resources Institute senior fellow Andrew Light, a former State Department adviser on India and climate issues. Both consider it a moral issue and an obligation to future generations, Light says, and both want progress to be part of their legacies.
That's translated into constructive cooperation, he notes. Over the past two years, Light says the two have expanded or created 15 joint climate and energy programs.
And in December's climate negotiations, he says, "the U.S. and India really did work very well in Paris to come up with compromises on the text that created an agreement that both of them could take home."
The Paris agreement goes into effect when 55 countries representing 55 percent of global greenhouse gas emissions ratify it. The world's two largest emitters, the United States and China, have announced they will do so by the end of the year. Several other emitters have as well. If India joins, that would push the total over the 55 percent threshold.
Democratic presidential frontrunner Hillary Clinton has praised the Paris agreement, but presumptive Republican presidential nominee Donald Trump says he would cancel it.
If India does ratify this year, Light adds, it would show that "this message that big developing countries in the world are not serious about Paris, are not serious about doing something on climate change, is just simply false."
As soon as Modi returned from Paris, he called his cabinet secretaries together to put together proposals on efficiency improvements, according to Ajay Mathur, director general of The Energy and Resources Institute (TERI), based in India.
Mathur says the most important program to come out of that effort aims to improve agricultural irrigation pumps, "which are notorious for their low efficiency."
Another aims to make air conditioners more efficient, a key effort, Mathur says, because "one of the largest growth areas in energy in India is the air conditioning sector."
In 2014, Modi set a target of 100 gigawatts of solar generating capacity by 2022 -- an extremely ambitious goal considering that the entire world's capacity that year was 177 GW and India had 2.4 GW.
The government has approved 15 GW of new capacity this year. But the long-term goals look harder to reach.
"What India needs is finance," Light says. "With some 240 million people not having access to electricity now, India essentially has the biggest single-country electricity market in the world. This is a huge investment opportunity."
But investors have not been eager to dive into India's complicated business environment. U.S. and Indian government efforts are "way too small to tackle this incredibly critical and important problem, and progress on them has been very slow," Light notes.
At the same time, India plans 290 GW of new coal-fired capacity by 2030, according to a Climate Action Tracker report, a huge setback for global greenhouse gas emissions.
"The question with fighting climate change has never been, 'Are people going to start using solar power?'" says Oren Cass, energy policy researcher at the Manhattan Institute. "It's been, 'Can you persuade the developing world to not build new fossil fuel power?'"
Given the rate that electricity demand is expected to grow in the developing world, Cass says the answer is almost certainly no. By 2040, power generation in non-OECD countries will be more than twice what it was in 2011, according to the U.S. Energy Information Administration.
"The growth in renewables doesn't get you anywhere close to leveling off growth in fossil fuels, let alone reducing [it]," he says.
Besides, Cass says, India has not pledged to reduce its greenhouse gas emissions. It only pledged it to reduce the intensity of its emissions per unit of GDP, which, Cass notes, is happening anyway.
In contrast, he adds, "The United States has now committed to making very dramatic and costly emissions reductions...in return for getting nothing from other countries." Cass considers the Paris agreement a "disaster" because it "let everybody else off the hook."
"The Paris agreement doesn't do nearly enough," agrees Niven Winchester, climate economist at the Massachusetts Institute of Technology. But Paris is a starting point, he adds. "If nations can't agree to the Paris agreement, there's no way we're going to meet the 2 degree target."
But Winchester says if India does ratify it, then India's allies would be more likely to follow, kicking off a "snowball effect."