Energy and Human Ambitions on a Finite Planet, 2021a

9 Climate Change 140
When the measurements started, the atmosphere consisted of less than
320 parts per million by volume (ppm v ), or < 0.032%. By now, we are
beyond 410 ppm v .
Measurements of trapped air bubbles in the Greenl<strong>and</strong> ice sheet going
back about 100,000 years <strong>and</strong> the Antarctic ice sheet going back 800,000
years indicate that CO 2 has fluctuated between 180–280 ppm v , reaching
the higher end of the range during the warmer periods between ice
ages (interglacial periods). For at least the last thous<strong>and</strong> years before the
Fossil Fuel Age, CO 2 held steady around 280 ppm v .
9.1.2 CO 2 Expectations
16
14
12
gas
2
TW
10
8
6
4
2
oil
coal
0
1800 1850 1900 1950 2000
year
kW/person
1
coal
gas
oil
0
1800 1850 1900 1950 2000
year
Figure 9.2: Historical use of fossil fuels
worldwide, repeated from Figure 8.2 [16].
On the left is the raw usage rate expressed in
terawatts, while the right is a per-capita measure.
The three fossil fuel types are stacked
on top of one another, so that gas makes
the smallest contribution, not the largest.
For instance, on the right-h<strong>and</strong>-edge of the
left panel, coal goes from 0 to 5 TW, oil
from 5 to 11 (thus 6 TW from oil), <strong>and</strong> gas
from 11 to 15, indicating 4 TW from gas. The
left-h<strong>and</strong> panel makes clear that fossil fuel
use is still rising dramatically, <strong>and</strong> thus CO 2
emissions.
We saw in Figure 8.2—repeated as Figure 9.2—a history of fossil fuel
usage for the world, in coal, oil, <strong>and</strong> natural gas. Meanwhile, Table 9.1
indicates how much CO 2 each fuel contributes per kilogram or Joule
used. These two pieces can be combined to make an estimate of how
much CO 2 is emitted globally each year, <strong>and</strong> to track total CO 2 emission
over time. Table 9.2 <strong>and</strong> Box 9.1 elucidate how to go from the fossil fuel
power figures (TW) in Figure 9.2 to CO 2 atmospheric concentrations.
Box 9.1: Computing CO 2 ppm v from TW
We will use oil as an example. In Figure 9.2, we appear to get about
6 TW from oil (5 TW from coal, 4 TW from natural gas). Multiplying
by 10 12 puts this in Watts (J/s) <strong>and</strong> by 3.156 × 10 7 seconds per year
results in the annual global energy from oil in Joules: 1.9 × 10 20 J/yr.
Table 9.1 indicates that oil contains about 11.5 kcal/g, so the number
of grams of oil used per can be determined by first converting J to kcal
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.