Wired: “Group Touts Seaweed As Warming Weapon.”
The idea is simple: deforestation? No problem – just use the vast amounts of space out there in the oceans to grow a bunch of seaweed and algae of various sorts, which apparently photosynthesize carbon dioxide “at rates comparable to the mightiest rain forests.” Better: they grow quickly.
Critics say that this isn’t truly carbon sequestration if the seaweed is then fed to people, because then the carbon is released right back out. I clearly don’t know enough of the mechanics of photosynthesis – I thought the carbon was transformed and/or incorporated into more complex structures, not merely stored? And if it’s stored as something other than carbohydrates and (as the Wired article says) the carbon is released into the atmosphere as seaweed decomposes, isn’t it a good idea to feed it to people, then?
Ahha, gummint scientists to the rescue:
Q. Should we be concerned with human breathing as a source of CO2?
A. No. While people do exhale carbon dioxide (the rate is approximately 1 kg per day, and it depends strongly on the person’s activity level), this carbon dioxide includes carbon that was originally taken out of the carbon dioxide in the air by plants through photosynthesis – whether you eat the plants directly or animals that eat the plants. Thus, there is a closed loop, with no net addition to the atmosphere.
Anyway. The question of using seaweed to combat the insanely high levels of carbon dioxide humans put out is only beginning to be explored, but already it is an interesting idea!