Sunday, January 12, 2014

Climate Change: The Next 10,000 Years

Once you transfer CO2 from the ground to the atmosphere, it changes the climate for a long time. David Archer's book The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate (Science Essentials) is definitely recommended reading, as are some of his papers over the last decade.

Andrew MacDougall had a nice little paper in GRL recently: "Reversing climate warming by artificial atmospheric carbon-dioxide removal: Can a Holocene-like climate be restored?"

The answer is no, the Holocene cannot very easily be restored.

MacDougall sets up the problem:
...long-term model simulations also indicate that most of the temperature anomaly created by burning of fossil fuels will persist even 10000 years into the future. The simulations of Eby et al. [2009], for example, suggest that 70–80% of the peak surface temperature anomaly would remain by the year 12000 CE, for a large range of cumulative carbon emissions (160–5120 Pg C). Given these model findings any attempt to return atmospheric concentration of CO2 to a “safe” level (after having greatly exceeded such a threshold) will likely require synthetic removal of carbon from the atmosphere.
10,000 years. That is definitely not something the general public understands. I wonder if even the politicians who take climate change seriously understand this.

To correct this, to something like 350 ppm (dot org), you have to remove more carbon than has been put into the system:
"Due to hysteresis in the permafrost carbon pool, the quantity of carbon that must be removed from the atmosphere is larger than the quantity that was originally emitted (115–180% of original emissions). In all the reversibility simulations with a moderate climate sensitivity, a climate resembling that of the Holocene can be restored by 3000 CE."
The year 3000. And that's if you do a lot of heavy work removing CO2 from the air and burying it somewhere. Today that costs about $50 per metric ton if you capture it at a power plant smokestack; no one really knows what it will cost to extract it from the air (as I wrote about in Physics World last year).

We are messing things up for a very long time.

No comments: