The final episode focuses on the environmental problems facing the South Pacific. Climate change threatens many islands, because they are low-lying and could be engulfed by rising seas. On Tuvalu, seawater bubbles up through the ground at high tides, making evacuation a realistic possibility. Oceans absorb half of all atmospheric CO2, but this turns them acidic, preventing sea creatures from building calciferous shells. The most immediate threat is overfishing. Reef damage by boats and tourism affects fish populations, but coral gardeners in Fiji have a solution.
