By Chris Adams

On the coast of Chile, a beach is littered with trash.

In Belize, trash from a fast-growing town is dumped at the edge of a mangrove forest and periodically pushed into the water, where high tides or storm surges will carry it away.

And when researchers cut open a dead albatross found at Midway Atoll in the Pacific Ocean, they found its stomach cavity filled with bottle caps and other bits of plastic.

Those are some of the images George Leonard shared with National Press Foundation fellows during a session that explored plastics and other trash in the ocean and the impact they have on marine life and the environment.

Leonard (bio, Twitter) is chief scientist for Ocean Conservancy, an advocacy organization, and he documented the extent of the worldwide trash problem that has emerged during a 200-fold increase in plastics production over the past 70 years. Half of all the trash in the oceans comes from Southeast Asia, with China the main offender. The U.S. contribution to the oceans trash problem is relatively small.

The global problem is only getting worse, and by 2025, there could be one ton of plastic in the ocean for every three tons of fish.

But, as Leonard asked: “Is there an impact here, or is this really just a visual problem?”

Leonard reviewed the scientific literature, saying there is broad evidence for impacts at the individual level from microscopic to macroscopic marine debris. Beyond that, there is evidence from the outside the marine realm of plastic impacts at the cellular and tissue level.

But studying the impact of trash on sea life populations is tricky, and only a dozen or so studies have attempted to do so. For example, it’s challenging – if not impossible – to do population experiments on the impact of marine debris on whales.

How to solve the problem? It’s not going to be easy. “There’s a sense that people are looking for a silver bullet,” Leonard said. He discussed efforts to ban the kind of plastics that are seemingly everywhere – from straws to grocery bags – but acknowledged that making real changes will take broad international cooperation.