BANGWEULU WETLANDS, Zambia – Out here on the endless swamps, a harsh truth has been passed down from generation to generation: There is no fear but the fear of hunger.

When I began my term as a public policy scholar at the Wilson Center last year working on the project “Science and the Media,” I ran into a journalist colleague I hadn’t seen in years. When he heard what I was doing, he said in astonishment, “Science? How did you get interested in that?”

“We don’t know the reason for the death of fish in downstream villages,” Hamberton Nongtdu, a mine owner from the northeastern Indian state of Meghalaya, told me.

Despite some critics, the recent U.S.-China agreement over carbon emissions has sparked remarkable optimism in global climate negotiations. It’s also opened the door to new bilateral engagement between the U.S. and Chinese environmental communities on other issues, including China’s massive air pollution problems (16 of the world’s 20 most polluted cities are in China).

Imagine an overgrown perennial garden. Impenetrable, shrubby bushes knit themselves together in long rows. Grasses reach chest high. Native hardwood trees hog the perimeter.

The Pangani River in Tanzania is important for many reasons: its three major dams provide 17 percent of the country’s electricity; it sustains thousands of farmers and herders living in the basin; and its flow of fresh water supports humans, industry, and ecosystems. But most interesting might be the innovative water policies that govern withdrawals, infrastructure projects, and ecosystems along its banks.