This fall, a series of significant events signaled what many see as a shift toward meaningful collective action on climate change.

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

Global population growth is so rapid that even the most severe crises imaginable would still leave the planet with more people than it can sustainably support, according to a recent study by the University of Adelaide’s Corey Bradshaw and Barry Brook published in the Proceedings of the National Academy of Sciences.

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.

The culmination of five years of work by three working groups comprising hundreds of scientists around the world, the Intergovernmental Panel on Climate Change’s Fifth Assessment was released in parts throughout this year. A newly released synthesis presents their findings in one document.