Amid the worry about water and food scarcity, some hints of good news: a five-year, 30-nation analysis suggests there might be enough water – and therefore enough food — for Earth’s hungriest and thirstiest as the human population heads toward the 9 billion mark sometime around mid-century.

Anxiety about food and water supplies stems in part from the effects of climate change, with its projected rise in droughts, wildfires, floods and other events that cut down on food production. Another factor is the increase in population, much of it grouped around water sources in the developing world. But water experts said at a conference this week in Brazil that there could be plenty of water over the coming decades if those upstream collaborate with those downstream and use water more efficiently.

The leader of the study, Simon Cook of the International Center for Tropical Agriculture, said this is actually possible. And he said it wouldn’t require the repeal of the more selfish impulses of human nature.

Citing an article in Harvard Business Review, Cook said, “It’s not necessarily human to be totally individualistic. There’s substantial evidence that people can collaborate.”

In fact, Cook said, this kind of discussion between upstreamers and downstreamers — the ones most likely to be at odds over how water should be used — is already taking place. There is evidence that China’s involved in a project to enable hydropower development along the Mekong River, one of several huge river basins examined in the water study. “They’re actually engaged in dialog with the people who will be affected by it” in Laos, Cook said, with a bit of wonder in his voice. “So there are some glimmers of hope.”