Environmental Engineering Reference
In-Depth Information
Increasing emmissions
Stable emmissions
80% less
emmissions
Increasing
concentrations
Stable
Concentration
FIGURE S.4 The left panel shows illustrative examples (from calculations using the Bern Earth Model of
Intermediate Complexity, see Chapter 2 and Methods) of how carbon dioxide concentrations would be
expected to evolve depending upon emissions. Stable emissions (blue lines) do not result in stable con-
centrations because the source of carbon is much larger than the sink. Emission reductions larger than
about 80% are required if concentrations are to be stabilized (green lines). The right panel shows the best
estimates and likely ranges of global warming projected for various levels of carbon dioxide concentration
in the transient (blue) and equilibrium states, or climate sensitivity (red); see Table 3.1. As carbon dioxide
emissions increase, average global warming is projected to follow the blue curve. If concentrations of
carbon dioxide were to be stabilized, the global warming is expected to increase from the blue to the red
curve, as depicted by the arrow. Note that the equilibrium warming indicated in the figure incorporates only
feedbacks from water vapor, clouds, sea ice, or snow changes; the slower acting feedbacks incorporated
in Earth System Sensitivity may increase the warming (by about 50% over the values shown according to
one study by Lunt et al., 2010) {2.1, 3.2, 3.3}
century are expected to determine the commitments to these eventual future
changes, the sea level rise expected to occur in the 21st century is consid-
erably smaller, in the range of 0.5 to 1.0 m. Some semi-empirical models
predict sea level rise up to 1.6 m by 2100 for a warming scenario of 3.1°C,
a possible upper limit which cannot be excluded. {4.8, 6.1}
Some slow climate components could act as amplifiers that would greatly
increase the size and duration of the Anthropocene.
If elevated global temperatures were to persist for a thousand years or
more, some studies suggest that the resulting warming of the deep ocean
