Jökull - 01.01.2005, Page 1

Invited research article
Global Warming: Take Action or Wait?
Wallace S. Broecker
Lamont-Doherty Earth Observatory of Columbia University,
61 Route 9W/PO Box 1000, Palisades, NY 10964-8000 USA, broecker@ldeo.columbia.edu
Abstract — A serious split in opinion exists with regard to how to deal with the ongoing buildup of CO 2 in
our atmosphere. One group contends that, until the warming has more clearly expressed itself, we should put
off costly actions. The other group contends that, even if we were to take immediate action, the buildup of CO 2
is likely to reach an unacceptable level. Hence action must not be delayed. I stand with the second group.
My opinion has been molded by the failure of model simulations to yield the impacts anywhere near as large
as those attributable to orbital cycles, to ocean reorganizations, or to solar irradiance. These impacts are
well documented in the paleoclimate record. This suggests to me that the models lack important feedbacks
and amplifiers present in the real world. Hence they are more likely to underestimate the impacts of CO 2 than
overestimate them as the critics contend. The world’s energy consumption will continue to rise. Because it is
so cheap and so abundant, coal will dominate as supplier.
It is also my opinion that CO2 capture and burial will have to play a key role in the struggle to bring the
CO2 rise to a halt. Fortunately, it appears that capture and burial are technically and economically feasible.
The big question is whether the world can come together and make this happen before CO 2 has reached an
unacceptable level.
INTRODUCTION
Of all the changes wrought by human activity, the
buildup in our atmosphere of the greenhouse gases,
carbon dioxide, methane and nitrous oxide, has gen-
erated the most contentious debate. Environmentalists
warn that in the absence of firm action, over the next
century the warming caused by the ongoing buildup of
these gases will have adverse impacts on our planet’s
agricultural productivity, on its fresh water supply and
on its wildlife. Further, the melting of the polar ice
caps will cause sea level to rise, leading to the destruc-
tion of valuable coastal property. They point to an on-
going melt back of mountain glaciers, to the decrease
in Arctic sea-ice extent and to a progressive softening
of frozen tundra as evidence that the impacts of this
warming are already underway. They warn that in or-
der to avoid much larger future impacts we must stem
the buildup of CO2 produced by the burning of coal,
oil, and natural gas.
While almost all scientists expert in the subject
agree that global warming will bring about a host of
undesirable changes, a large segment of the public re-
mains unconvinced. This sentiment is reflected by a
reticence on the part of governments in the United
States, Australia, and China to join with Europe and
Japan in agreements to cut back on CO2 emissions.
The economic consequences of such actions are con-
sidered to be too large when weighed against what
they consider to be rather uncertain long-term conse-
quences of business-as-usual fossil fuel use.
CO2 PRODUCTION
The situation is made more complicated by the incred-
ible magnitude of the task. In 2005, worldwide some
25 billion tons of CO2 were produced by burning fos-
sil fuels. If captured and liquefied, this CO2would
nearly fill a tank three kilometers on a side and three
kilometers deep! Except for the contribution of the
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