It’s not as if we really need any more bad news from Hurricane Katrina. But a report in this week’s Science magazine has found that trees knocked down by the 2005 storm are putting a lot of carbon dioxide into the air as they decompose--roughly equal to all the carbon stored in a year’s worth of plant growth across the nation.
According to the article, "Hurricane Katrina killed or damaged about 320 million large trees, representing a loss of about 105 teragrams of stored carbon." One teragram is one million metric tons--and 105 teragrams is more carbon than emitted in a year by all the power plants in Texas (which is #1 in the nation in this category), according to the CARMA database at the Center for Global development.
Granted, the trees are doing something as natural as living and breathing. Plants take carbon from the air and store it in their tissues. Animals, fungi and bacteria do the opposite: we use plant tissues for energy and create carbon dioxide gas in the process. These activities tend to balance each other out, but unfortunately there’s not much left over for soaking up carbon dioxide created by burning fossil fuels.
This study points out the impermanence and fragility of forests. We short-lived humans tend to think of trees as living pretty much forever, and that’s why planting trees to counteract climate change seems like a good idea. But at some point in the not-too-distant future those trees will die, and all the carbon they painstakingly stored over their lifetimes will begin to leak back into the air. Bring on a hurricane (or a Southern California wildfire) and that leak turns into a torrent.