Thursday, 3 July 2008

Growing Like Weeds: The Answer to Green House Gases?

My neighbor is back in the city for a few days after passing some time at her cottage in the Laurentians. Things are incredibly green, she says, and growing like…well, growing like weeds. The immense amount of snow last winter plus frequent rain in late spring have combined to make this a bumper year for all sorts of plants.

Vigorously growing plants: therein lies a partial solution to the problem of green house gases, two recent articles suggest. The first, by Freeman Dyson in The New York Review of Books, notes that carbon in the atmosphere decreases during the growing season in the northern hemisphere. After discussing two new books dealing with global warming—one which argues that the long turn costs of doing nothing will equal the costs of several possible solutions—Dyson suggests that trees bred or genetically modified to take up carbon rapidly might effectively counteract what we’ve been doing to the atmosphere.

Then Sunday’s New York Times Magazine had a fascinating article about weeds by Tom Christopher, “Can Weeds Help Solve the Climate Crisis?” The scenario is pretty gloomy, looked at one way, because it appears that many weeds grow more vigorously as the carbon dioxide content of the air increases. Christopher says that kudzu is moving north and taking over more forests; ailanthus trees next to a major highway grow 20 feet in five years compared to five feet in the mountains; and if you make things tougher, the fittest weeds will thrive.

But this can be worked to our advantage. Specifically Christopher quotes weed expert Lewis Ziska arguing that kudzu roots could be a good source of ethanol, while the vines could be burned. But there are other possibilities. Christopher writes: “If we are to avoid disaster, experts agree, we will need to be tenacious but flexible, ready to identify and exploit any opportunity in what will be a challenging, even hostile situation. In this new world that we have made, weeds, our old adversaries, could be not only tools but mentors.”

One way to look at human history is continual destruction of forests. The Indian epic Rig Veda talks of a great forest which extended from the Indus to the Ganges; the Cedars of Lebanon were chopped down in part to build Babylon; Julius Caesar’s Europe was covered with forest; and the island of Madeira got its name because of its trees, which burned in a forest fire which lasted seven years in the 1420s. The deforestation of North America followed, and we now seem intent of finishing the job in Amazonia, Southeast Asia and elsewhere.

So there certainly is room for reforestation. Would doing this mean developing Dyson’s super trees? Or could we rely on weed trees to do the job? I have no idea, but it is time that some serious research was done on the subject.


Martin Langeland said...

Don't think we want to burn the plants as that releases carbon into the atmosphere -- same problem with corn and soy to alcohol operations.
The real trick is how to get a lot more efficient at what we do do. Need to use the waste emissions to make something. In a closed system whatever is discarded floats back into view. Usually obnoxiously.

Mary Soderstrom said...

I agree we have to make do with what we have. How can we use waste emissioins? Got any ideas?