Neither emissions reduction nor simple ocean fertilization will do much for the U.S. before we reach the 2°C (3.6°F) overheating frontier. That happens about 2028 when today’s toddlers finish high school.

But there’s still a class of climate fix that is analogous to plowing under a cover crop. If we immediately bury the new green stuff, we get a big boost in the efficiency of cleaning up excess carbon.

On land, one can grow extra greenery, then harvest and bury it somewhere that will keep its eventual carbon dioxide from making its way back into the circulating air. However, this too needs a lot of new growing space and water resources (and you have to keep it from burning in a time of worse droughts and higher winds)–all at a time when expanding human populations will contest such land and water use.

Not likely. What’s left, given that massive ocean fertilization looks unlikely to settle out enough carbon into the ocean depths? It turns out that we can augment settling out the new greenery with pumping it down.

In the ocean surface layer, three-quarters of the new green turns back into carbon dioxide within a week or two via respiration or rotting. Fortunately, we can use push-pull pumps to fertilize and then sink the new algae within days so that carbon dioxide production instead happens in the depths.