Every few years, people need to be reminded that carbon dioxide released into the atmosphere from fossil fuel combustion lasts a long, long, long time. How long?
A 2005 study by Geophysicist David Archer, “Fate of fossil fuel CO2 in geologic time,” (subs. req’d.) concluded that a large fraction of the CO2 emitted by humans last well in excess of 1000 years:
The mean lifetime of anthropogenic CO2 is dominated by the long tail, resulting in a range of 30–35 kyr.
That’s why we need to stop and reverse the growth of fossil fuel emissions immediately (see “Dr. Hansen to Dr. Merkel: Carbon is forever — so ban new traditional coal plants now”). That’s why we can’t have climate regulations that let companies keep burning coal while they buy rip-offsets.
In the interest of reminding people of this central fact of climate science, Nature online has published, “Carbon is forever.” Turns out Archer has a book out, The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth’s Climate, which has this useful figure:
Figure: Model simulation of atmospheric CO2 concentration for 40,000 years following after a large CO2 release from combustion of fossil fuels. Different fractions of the released gas recover on different timescales.
So we’re in the process of changing the climate (for the much, much worse) for 100,000 years. Hmm. I’ve been saying that if we don’t act now we’re going to ruin the climate for the next 50 generations to walk the planet. I guess I was being way too conservative (again).
“The climatic impacts of releasing fossil fuel CO2 to the atmosphere will last longer than Stonehenge,” Archer writes. “Longer than time capsules, longer than nuclear waste, far longer than the age of human civilization so far.”
It’s not just the carbon that could last forever:
The warming from our CO2 emissions would last effectively forever, too. A recent study by Caldeira and Damon Matthews of Concordia University in Montreal found that regardless of how much fossil fuel we burn, once we stop, within a few decades the planet will settle at a new, higher temperature. As Caldeira explains, “It just increases for a few decades and then stays there” for at least 500 years — the length of time they ran their model. “That was not at all the result I was expecting,” he says.
Bottom line: It’s great that one form of solid carbon is forever, as Shirley Bassey sings in the classic Bond movie, but not that the gaseous form is.
In other words, a few decades of prevention is worth 30,000 years of cure.