The Carbon Cycle - Introduction to Carbon Capture and Sequestration - page 134

experiences with cities, countries, and ecological resources. As scien-
tists we like to avoid hyperbole, but in the context of our present world
political and economic systems, this fi gure is apocalyptic.
Section 7
Concluding remarks
In the last section, we discussed an extreme example of how large-scale
carbon emissions can infl uence the climate for many years. The impor-
tance of this example is that the amount of carbon that was emitted in
the atmosphere during the PETM is of the same order of magnitude as
the total carbon content of all fossil fuels we have discovered so far. The
effects of emitting the corresponding CO 2 are large and will take about
100,000 years to subside.
We have also seen that the earth's carbon cycles are very complex
with many feedback loops. It would be impossible to fully understand
such a complex system. Thus, the predictions that we have discussed in
this topic contain uncertainties. These uncertainties are often the drivers
for new scientifi c inquiry, with particular attention to those uncertainties
that are largest and have the biggest impact.
If we look back 30 years, anthropogenic climate change used to be
a controversial topic in the literature. One can fi nd discussions arguing
that if climate change is ongoing, one would see an increase in the CO 2
concentration in the ocean. At that time there were no experimental data
to support this claim. Because of this scientifi c discussion between those
that argued in favor of and against the existence of climate change, an
experimental program was set up to measure whether such an increase
actually has taken place. The experiments showed that the ocean has
indeed taken up the additional CO 2 . Over the years heated discussions
have resulted in more innovative experiments to settle the disagree-
ments. Little by little the most pressing questions have been settled
simply by accumulating experimental evidence — not because the scien-
tists in favor had the best arguments or the loudest voices, but because