As we burn fossil fuels, carbon dioxide is seeping into the oceans and creating an alarming, science-fiction scenario. It's called ocean acidification. It could lead to a mass extinction of marine life, yet it is largely unknown to the public. In the Pacific Northwest, the Brothers meet scallop & mussel farmers who are already experiencing the impacts of this recent phenomenon and losing millions of dollars. Diving near a volcano in Italy that causes nearby waters to be naturally higher in acidity, the Brothers see first-hand what the rest of the ocean might look like in the future if the trend continues. Can we stop the problem of ocean acidification before it's too late?