[freebeard]

I suspected storm surge.

https://newatlas.com/wood-waste-bioc...oncrete/54195/

A 2010 study found that increasing the global production of biochar could offset over 10 percent of the world's human-caused greenhouse gas emissions. Due to its strong water absorption and retention capacity, biochar also is known to be a wonderful soil enricher.

In exploring other commercial applications for biochar, the team at NUS discovered that adding a small amount of it to cement or mortar mixtures made the resulting materials up to 20 percent stronger and 50 percent more watertight.