Almost all of the power on the island is supplied by fossil fuels, but Puerto Rico is “an ideal locale to use solar power and renewable energy because it has so many more solar days than in many parts of the world,” said Mr. Marvel, whose offices are based in Manhattan and San Juan. “We want to keep the candle burning with solar energy, not fossil fuel.”

Saving the Soil

The role that soil plays in climate change is often ignored, but changing the way it is managed could have a big impact on global warming.

Unfortunately, most soil has become less productive, with environmental consequences, said Michael Doane, managing director for agriculture and food systems at the Nature Conservancy. That’s because it has been eroded through too much tilling, lack of adequate ground cover and a failure to diversify crops.

“This living ecosystem has become dead and we’re trying to bring it back to life,” Mr. Doane said.

One pilot program, now taking place on more than 100 American farms in about six states, is focused on reducing or eliminating the amount of tillage done on farms. It is done under the auspices of the Soil Health Partnership, a collaboration of environmental groups, farmers, academics and industry working to alter soil health practices.

“Tillage is actually detrimental to soil,” he said. One of the main problems is that tilling releases carbon stored in the soil, which becomes carbon dioxide when exposed to air and contributes to global warming. Tilling also makes the earth more susceptible to erosion and less able to absorb heavy rainfalls.

One solution is using plants — either rotating crops or using ground cover such as grass, depending on what’s needed to repair the soil — to cover the soil before and after the main cash crop is planted. Diverse plant cover has been found to make the soil healthier and helps control weeds, Mr. Doane said.

“We want to try to avoid soil bare of plant cover,” he added. “Instead, our vision is a continuous living cover.” Calling it “nature’s solution to climate change,” he said the process of photosynthesis — where plants store the carbon in the soil and release oxygen — could be “a very cost-effective way to mitigate climate change.”