Environmental impact is complex and has multiple dimensions. Obsessing over carbon is dangerous.

It’s funny to think of those who would oppose it. There are actually many, like the poster who is concerned about biodegradability. It can’t sequester carbon if it also biodegrades. “Split wood, not atoms!”

> It can’t sequester carbon if it also biodegrades

This is misleading. Trees in a forest store carbon as long as the forest exists. Individual trees might degrade (or be trapped underground), but new ones are born.

And yet all of the sequestered carbon we are tossing into the air in the form of burning fossil fuels was once biodegrading organic matter... it's almost like "biodegrade" and "sequester" can coexist.

So is Geofoam a contributor to microplastic pollution or not?

Over time, there's no reason it wouldn't. It's expanded polystyrene with an eco-friendly name, and anything that would degrade EPS would degrade these blocks. Groundwater is the big one I'd be concerned about. It being dug up and trashed by future earthworks projects would be the second big thing.

> It can’t sequester carbon if it also biodegrades.

How does biodegrading release carbon?

Natural biodegradation usually releases at least part of the carbon via CO2.