It’s officially World Oceans Day, an opportunity to explore the importance of our oceans and their rich diversity of life. It’s also a chance to highlight what Daniel Hinerfeld of the Natural Resources Defense Council (NRDC) calls "the scariest environmental problem you’ve never heard of".

Hinerfeld is the writer, co-director and executive producer of "Acid Test: The Challenge of Ocean Acidification", a documentary narrated by Sigourney Weaver. He says that although he has worked at NRDC for six years, he knew virtually nothing about ocean acidification before starting work on the film -- and he’s betting that a lot of you haven’t heard of it, either.

“That knowledge gap seems particularly weird once you start talking to the scientists who work on this issue,” Hinerfeld writes on NRDC Switchboard. “They are freaked out. They are so alarmed about what the future holds for the oceans (if we don't change our carbon-emitting ways) that they seem to be losing a battle against despair.”

“There are solutions, of course, but first, here's a basic explanation of ocean acidification: The atmosphere touches the ocean over about 70 percent of Earth's surface, so a significant percentage of the carbon dioxide we emit by burning fossil fuels ultimately mixes with ocean water. That interaction produces carbonic acid. The more CO2 we put into the atmosphere, the more CO2 ends up in the ocean and the higher ocean acidity goes.”

Models show that ocean acidity will double if we don’t cut CO2 emissions, making oceans so acidic that a complex web of shelled creatures including plankton, corals and shellfish won’t be able to build their shells. That could have a dramatic impact on entire oceanic ecosystems.

So, how can we stop this from happening? As Hinerfeld suggests, we must learn to power our lives without emitting huge quantities of CO2.

As part of their Blue August ocean-themed programming this summer, Planet Green will host the world premiere of "Acid Test: The Challenge of Ocean Acidification" in August. Check out the trailer over at PlanetGreen.com.

You can also learn more about ocean acidification at the NRDC website.