Environmental Engineering Reference
In-Depth Information
Table
Removal time and percentage contribution to climate
forcing of several greenhouse gases in the year
.
Agent
Removal time
Approximate contribution
Carbon dioxide
>
years
%
Methane
years
%
Tropospheric ozone
days
%
Nitrous oxide
years
%
Fluorocarbons
>
years
<
%
Sulfate aerosols
days
%
Black carbon
days
þ
%
consequences for a very long time, no matter how hard
we try to
fix things.
the US National Academy of Sciences, at the
request of the White House, reviewed the data on green-
house gas persistence in the atmosphere and the contri-
bution that each of the gases makes to what is called
climate forcing. Climate forcing is the technical term that
is related to the change in temperature caused by green-
house gases. Table
In
] gives the
removal time (how long it would take for something to
come out of the atmosphere if we stopped adding to it)
and the percentage contribution to total climate forcing
from
.
from the NAS report [
concentrations of each of the main contribu-
tors to climate change. A positive contribution means
warming while a negative one means cooling. The one
negative contributor is sulfate aerosols which contribute
to cloud formation, thereby re
ecting more of the incom-
ing solar energy back into space.
Carbon dioxide, the main addition to greenhouse gases,
contributes
% of the warming coming from all the
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