NEW YORK (Thomson Reuters Foundation) - Implementing the Paris climate agreement by investing trillions of dollars to slow greenhouse gas emissions would be far cheaper than paying the costs of people sickened by polluted air, scientists said on Friday.

Governments worldwide could save $54 trillion in health care by investing less than half that amount in green projects by mid-century, researchers said in a study published in The Lancet Planetary Health, an online academic journal.

Such an investment would result in 30 million fewer premature deaths related to air pollution, said the study’s co-author Jon Sampedro, a researcher at Spain’s Basque Centre for Climate Change.

The Paris agreement reached in 2015 by nearly 200 countries committed to curbing greenhouse emissions enough to keep the global hike in temperatures “well below” 2 degrees Celsius (3.6 Fahrenheit) above pre-industrial times while “pursuing efforts” for a far tougher 1.5 C ceiling.

A United Nations draft report earlier this year projected that unless governments take unprecedented measures, the global temperature rise is on track to exceed the accord’s tougher target.

Authors of the study said their calculations of steep savings could convince policy-makers to adopt more aggressive policies to curb human emissions of greenhouse gasses that include carbon dioxide from burning fossil fuels.

“We hope (that) ... might help policymakers move towards adopting more ambitious climate policies and measures to reduce air pollution,” said Anil Markandya, a professor at the Basque Centre, in a statement.

The team of researchers from Spain, the United States and Italy ran computer models that combined future estimates of emissions, air pollution-related deaths and healthcare benefits for the entire world.

Achieving the highest levels of savings would require China and India making the largest joint investment, some $9 trillion, to tackle climate change, the study said.

The two countries would then save most by having healthier populations, it said.

Together China and India account for about a third of global emissions, according to the World Resources Institute, a Washington-based think tank.

The Paris agreement allowed nations to set their own targets to slow climate change, with no sanctions for non-compliance.

President Donald Trump announced last year he was pulling the United States, the world’s second biggest emitter of heat-trapping carbon dioxide, out of the deal. China is the biggest such emitter.

His decision isolates the United States as the only country opposed to the pact.