At Scotland's University of Edinburgh, researchers are developing a minuscule tube that can suck carbon dioxide out of the air. Each tube measures just 1 micrometer long by 1 nanometer in diameter, and a square meter of them could soak up as much carbon as 10 trees.
Eleanor Campbell, the professor leading the research, says the nanotube technology can replicate nature's work: “In some ways,” she said in a press release, “the unit would work like an artificial tree.” In fact, it has some advantages over trees: Nanotubes don’t die, they don’t require particular soil chemistries, they’re not sensitive to cold snaps, they don’t get confused and start blooming in November if the thermometer rises above 60 degrees. Campbell suggests one “key advantage” of the nanotubes is that they can be used in urban areas, “where tree planting is not possible.”
But trees process carbon dioxide, while nanotubes simply store it. The technology being developed at Edinburgh won’t be commercially available for a few years, but in theory, this is how it would function: After the nanotubes have done their work, they’d be relieved of their carbon dioxide burden. The carbon dioxide would be concentrated, poured into small canisters and stored deep underground. It’s another path to carbon sequestration—one American company is working to develop nanotube membranes for use directly in carbon-spewing smoke stacks.
The nanotube technology is also a kind of geoengineering, which aims to slow climate change by capturing carbon. Planting trees counts as a type of geoengineering, too, because it performs the same carbon-capturing function. It’s tempting to think of afforestation as a more “natural” way to fight climate change, but it too is a project subject to human failings and whims. Scientists are still figuring where and how newly planted trees can best fight climate change. As a rule of thumb, trees in the tropics help, trees in more northern latitudes don’t. In some places, planting trees may actually exacerbate climate change, as the dark trees absorb more heat than the landscape they replace.
Technologies like this one force an uncomfortable question: What if the best way to limit the effects of climate change isn't natural at all? Opponents of geoengineering tend to believe that humans aren’t clever enough to predict how their actions will affect the planet. But a growing number of advocates are starting to believe there won't be any other choice.