How can we reduce the greenhouse gases that cause climate change when most developing nations need more energy than ever before?

Renewable energy sources emit far less CO2 than traditional fossil fuels. But critics argue renewables like solar and wind are too expensive.

No more. Innovation and research have lowered the cost of many renewables to — and sometimes below — fossil-fuel prices.

How low can they go?

At least 29 to 65 percent lower, says the International Renewable Energy Agency. That’s how much the total installed costs of utility-scale solar-power systems dropped in just the last four years. (Just how much depends on location.) Onshore wind power now consistently matches or beats fossil-fuel prices. And renewable hydropower technology can provide the cheapest electricity of all.

(State Dept./Julia Maruszewski)

“Decades of research by government and industry have reduced costs to make renewables much more competitive than ever before,” said Lynn Orr, U.S. under secretary of energy for science and energy. “We will look back on this time as one of rapid acceleration in the transition from today’s energy systems to the low-carbon sources of the future.”

Affordable renewables “will help provide better air quality and greater energy security,” adds Cédric Philibert, a senior analyst at the International Energy Agency. Their increasingly lower cost will help governments achieve the carbon-reduction goals they have set in advance of the COP21 conference in Paris, he said. “It has already changed significantly the tone of the climate-change conversation.”