As a diver in the 1970s, marine ecologist Enric Sala saw once-lush oceanscapes reduced to underwater deserts — but later, in marine preserves across the globe, he also witnessed the ocean’s power to rejuvenate itself when left to its own natural devices. Could rewilding the planet help us restore biodiversity and reduce the impacts of climate change? Sala presents the 30×30 initiative: a global plan to protect 30 percent of the Earth’s surface and the ocean floor by 2030.