Eats, shoots, and leaves

Are we doing carbon storage right? ProPublica reports that a program in California that was supposed to offset carbon dioxide emissions with matching carbon capture (through forest plantings) hasn't really resulted in net carbon storage and is instead facilitating higher emissions (permitted by the offsets).

■ Everyone knows that plants consume carbon dioxide, "exhale" the oxygen, and use the carbon to grow. So far, so good. And big plants will tend to contain more carbon than small ones (at least, per square foot of ground covered).

■ We look at trees in particular because forests are aesthetically pleasing, they can grow in places that are otherwise not ideal for agriculture or habitation, and they can sequester quite a lot of net carbon.

■ As long as the trees are allowed to mature, they can store a lot of carbon. That, clearly, sequesters the carbon away from the atmosphere. But even though that storage has been increasing for the last three decades, it's not the kind of increase we can accelerate very quickly. Most of the carbon in a tree is stored in the trunks and branches, and trunks don't grow very quickly.

■ Presumably, the way to passively remove carbon from the atmosphere at the highest speed is to find the fastest-growing plants that can then be harvested and stabilized (since it doesn't do any good to capture the carbon only to have it decompose quickly and return to the atmosphere). Fast growth is the champion. Decomposition is the enemy.

■ Bamboo is the fastest-growing woody perennial plant, and it is useful for long-duration carbon sequestration in textiles and building materials. For any plant (tree, bamboo, or otherwise), the optimal solution from a carbon-sequestration perspective is if it can be harvested and used in some durable way that doesn't involve combustion or consumption and digestion by an animal. Then, the harvested plant can be replaced with a new plant cultivated in its place, increasing the net impact.

■ Thus, this question: Is there a reason why we aren't genetically modifying bamboo so it grows more productively and easily in cold-weather climates? Wouldn't bamboo capture and store more carbon than trees in less time? Bamboo certainly shouldn't be used to replace trees, but if carefully managed, it might well serve as a fast-acting enhancement to carbon sequestration.

Not just nice as a side dish