For nearly a decade, Sierra has been ranking U.S. colleges on their greenness. And every year, our readers ask why we don’t include schools outside our national borders.

Here’s the honest answer: The world is too big. To put together our annual list, we partner with the Association for the Advancement of Sustainability in Higher Education to survey hundreds of colleges. Then we spend months analyzing their responses (all of which are published here) and crunching the relevant numbers. The result is a thorough, accurate, and trusted ordering of America’s most environmentally oriented schools. Assessing the entire world, however, is beyond our capacity.

Still, amazing stuff happens at colleges abroad. Which is why this year, we’re including stories that feature plucky souls from around the world who took it upon themselves to clean up their campus and, by default, their corner of the planet, even when the odds were stacked against them. We meet young anti-plastic warriors from Senegal, Puerto Rico, and New Zealand who overcame serious challenges to get an unsustainable form of waste out of waterways and landfills. And we learn how activists on college campuses have swayed governments and multinational corporations to divest from fossil fuels.

Click here, though, to find out who dominates stateside. Here’s a hint: The West Coast is doing a stellar job of making sure its campuses adhere to strict environment-saving standards. The University of California system alone occupies 4 of our coveted top 10 slots.

Our hope is that you’ll finish this issue with a buoying sense of optimism about the coming generation of college students, no matter where they live. They know that they’re on the cusp of inheriting this planet, and that they’ve got what it takes to save it.