present rate of increase of consumption. ... the check to our progress must become perceptible within a century from
the present time. ... the conclusion is inevitable, that our present happy progressive condition is a thing of limited
duration.” Jevons was right. Within a century British coal production indeed peaked, and there were two world wars.
8Dominic Lawson, a columnist from the Independent. My quote is adapted
from Dominic Lawson’s column in the Independent, 8 June, 2007.
It is not a verbatim quote: I edited his words to make them briefer but took
care not to correct any of his errors. All three numbers he mentions are in-
correct. Here’s how he screwed up. First, he says “carbon dioxide” but gives
numbers for carbon: the burning of fossil fuels sends 26 gigatonnes of CO2
per year into the atmosphere (not 7 gigatonnes). A common mistake. Sec-
ond, he claims that the oceans send 36000 gigatonnes of carbon per year
into the atmosphere. This is a far worse error: 36000 gigatonnes is the total
amount of carbon in the ocean! The annual ﬂow is much smaller – about 90 gi-
gatonnes of carbon per year (330 GtCO2/y), according to standard diagrams
of the carbon cycle [ ] (I believe this 90 GtC/y is the estimated ﬂow
rate, were the atmosphere suddenly to have its CO2 concentration reduced
to zero.) Similarly his “1900 gigatonne” ﬂow from biosphere to atmosphere
is wrong. The correct ﬁgure according to the standard diagrams is about 120
gigatonnes of carbon per year (440 Gt CO2/y).
Incidentally, the observed rise in CO2 concentration is nicely in line with what you’d expect, assuming most of the
human emissions of carbon remained in the atmosphere. From 1715 to 2004, roughly 1160 GtCO2 have been released
to the atmosphere from the consumption of fossil fuels and cement production (Marland et al., 2007). If all of this CO2
had stayed in the atmosphere, the concentration would have risen by 160ppm (from 280 to 440 ppm). The actual rise
has been about 100ppm (from 275 to 377ppm). So roughly 60% of what was emitted is now in the atmosphere.
10Carbon dioxide has a warming effect. The over-emotional debate about this topic is getting quite tiresome, isn’t it?
“The science is now settled.” “No it isn’t!” “Yes it is!” I think the most helpful thing I can do here is direct anyone
who wants a break from the shouting to a brief report written by Charney et al. (1979). This report’s conclusions
carry weight because the National Academy of Sciences (the US equivalent of the Royal Society) commissioned the
report and selected its authors on the basis of their expertise, “and with regard for appropriate balance.” The study
group was convened “under the auspices of the Climate Research Board of the National Research Council to assess
the scientiﬁc basis for projection of possible future climatic changes resulting from man-made releases of carbon
dioxide into the atmosphere.” Speciﬁcally, they were asked: “to identify the principal premises on which our current
understanding of the question is based, to assess quantitatively the adequacy and uncertainty of our knowledge of
these factors and processes, and to summarize in concise and objective terms our best present understanding of the
carbon dioxide/climate issue for the beneﬁt of policy-makers.”
The report is just 33 pages long, it is free to download [ ], and I recommend it. It makes clear which bits of the
science were already settled in 1979, and which bits still had uncertainty.
Here are the main points I picked up from this report. First, doubling the atmospheric CO2 concentration would
change the net heating of the troposphere, oceans, and land by an average power per unit area of roughly 4 W/m2,
if all other properties of the atmosphere remained unchanged. This heating effect can be compared with the average
power absorbed by the atmosphere, land, and oceans, which is 238 W/m2. So doubling CO2 concentrations would
have a warming effect equivalent to increasing the intensity of the sun by 4/238 = 1.7%. Second, the consequences
of this CO2-induced heating are hard to predict, on account of the complexity of the atmosphere/ocean system, but
the authors predicted a global surface warming of between 2°C and 3.5°C, with greater increases at high latitudes.
Finally, the authors summarize: “we have tried but have been unable to ﬁnd any overlooked or underestimated
physical effects that could reduce the currently estimated global warmings due to a doubling of atmospheric CO2 to
negligible proportions or reverse them altogether.” They warn that, thanks to the ocean, “the great and ponderous
ﬂywheel of the global climate system,” it is quite possible that the warming would occur sufﬁciently sluggishly that it