I’m not sure whether Ken Caldeira is a dioxycarbophic or a dioxycarbophiliac. He certainly appears to have an odd fixation with it.
He also appears to think other researchers are idiots who completely botched their soil carbon exchange monitoring experiments, as if he’s the only one who ever thought of degrading subsoil vegetation in previously cleared farmland.
And then there’s the bizarre claims about CO2‘s atmospheric persistence
Here’s a pretty picture from NASA:
Source: Nasa’s “The Carbon Cycle” feature
I used that one because it’s a bit prettier (and less used) than the ones I keep putting up from the IPCC.
Note that there’s a listed “pool” of 800 Gt of carbon
dioxide in the atmosphere and an annual sequestration of 215 Gt.
Obviously then 215/800 or about 27% of the carbon pool is recycled each year. So how long would a molecule of human-emitted CO2 persist in the atmosphere. A few years? 10? 100? 1,000?
Actually the decline of the “human portion” is quite rapid. If you look at the proportion of an “original atmosphere” and its depletion it works like this:
In year 1 you have 100% with 27% exchanged – only 73% of the original atmosphere’s CO2 remains.
After year 2 this depletes to 53% of the total pool.
At the end of year 3, 39% remains.
Year 4, 29%, so after 4 years 70% of your original atmospheric carbon dioxide pool has already been exchanged, only ~30% remains.
After 20 years only 0.3% of your original stock remains, the rest has been absorbed by the biosphere.
Obviously exchanging every last molecule takes quite a while because it becomes a disappearingly small proportion of the atmosphere. Thus those with an unhealthy fascination with CO2 can be technically correct claiming human influence on atmospheric CO2 could persist for a thousand years but as this graph of depletion demonstrates the effect is halved in a couple of years and less than 5% in a single decade:
Update: – Elevated from the comments, below. Corey has raised the technical issue of some persistence implies perturbation, no matter how slight, which is true. I would suggest the biosphere will absorb all meaningful additional CO2 in a short while.
The following graphic depicts the current “excess” carbon dioxide (120 ppmv) and assumes biospheric drawdown will decline about 20% per decade as it depletes the resource. Currently the biosphere is consuming about 20Gt (~60%) of anthropogenic emissions annually. “Excess” CO2 would be halved in 3 decades and in fact that would take it below the point we believe we observed any effect. X-axis is decades, Y is CO2 “excess” in ppmv.
Other of Ken & co’s claims are pretty dubious simply from the ice core record – if accurate (and it is what the IPCC and everyone bases their claims upon) then atmospheric carbon dioxide levels did not change measurably prior to 1750 or even 1850 for significant effect. Why would they then be interested in modeling “pre-industrial emissions” if it didn’t change the atmospheric content?
Weird but they are so impressed with themselves they’ve got two press releases in EurekAlert:
Washington, D.C.— When evaluating the historic contributions made by different countries to the greenhouse gasses found in Earth’s atmosphere, calculations generally go back no further than the year 1840. New research from Carnegie’s Julia Pongratz and Ken Caldeira shows that carbon dioxide contributions from the pre-industrial era still have an impact on our climate today. Their work is published in Environmental Research Letters.
The burning of fossil fuels that came with industrialization released massive amounts of carbon dioxide emissions into the atmosphere, which has caused global warming. But clearing forests and other wild areas for agricultural purposes also contribute to atmospheric carbon dioxide, and that has been happening since before industrialization.
When unmanaged land is cleared for farming, part of the carbon is released immediately into the atmosphere as a result of burning. The rest of the carbon, including that from roots and wood products, releases carbon as the wood decays over years and centuries, meaning that carbon from pre-industrial activities is still being emitted into the atmosphere. Furthermore, a part of carbon dioxide emissions remain in the atmosphere for many centuries, because the ocean and vegetation on land absorb carbon dioxide only slowly over time. As a result, there is a warming effect long after the initial clearing of land.
A climate model accounting for the carbon dioxide (CO2) released into our atmosphere before the industrial revolution has been used to show the detrimental effect of carbon emissions on global temperature in the long-term.
In a study published today, 4 July, in IOP Publishing’s journal Environmental Research Letters, researchers from the Carnegie Institution for Science have shown that pre-industrial emissions from land use changes are responsible for about nine per cent of the increase in today’s global mean temperature since that era.
“The relatively small amounts of carbon dioxide emitted many centuries ago continue to affect atmospheric carbon dioxide concentrations and our climate today, though only to a relatively small extent,” said co-author of the study Julia Pongratz.
“But looking into the past illustrates that the relatively large amount of carbon dioxide that we are emitting today will continue to have relatively large impacts on the atmosphere and climate for many centuries into the future.”
Having modelled pre-industrial emissions from around the world, the researchers calculated the effect on emissions of the five-fold population increase between 850 and 1850 AD.