Environmental Engineering Reference
In-Depth Information
Multi-model averages and assessed ranges for surface warming
©IPCC 2007: WG1-AR4
A2
A1B
B1
Year 2000 constant
Concentrations
20th century
6.0
5.0
4.0
3.0
2.0
1.0
0.0
-1.0
1900
2000
Ye a r
2100
FIGURE 6.45
Projected
Δ
T
for our planet as per the IPCC 2007 Assessment. (Reprinted
from Solomon, S., Qin, D., Chen, Z., Marquis, M., Averyt, K.B., Tignor, M., and. Miller, H.L.
(Eds)
IPCC 2007:Climate Change 2007:The Physical Basis. Contribution of working group 1
tothefourthassessmentreportoftheIntergovernmentalPanelonClimateChange,
Cambridge,
United Kingdom, and NewYork: Cambridge University Press, 996 pp.)
is a constant,
P
CO
2
is the current partial pressure of CO
2
, and
P
CO
2
is the
reference partial pressure of CO
2
. Thus, the increase in surface temperature is a non-
linear function of
P
CO
2
. If we define a scaling factor,
where
η
T
∗
, which is the temperature
Δ
T
∗
= η
increase due to a doubling of
P
CO
2
, we obtain
Δ
ln 2. Therefore,
ln
P
CO
2
P
CO
2
.
Δ
T
∗
ln 2
Δ
T
=
(6.168)
Each of the GHG will contribute a certain
Δ
T
and hence the cumulative change
T
overall
=
i
(
is
T)
i
. The increase in temperature of the surface can have catas-
trophic consequences. The most recent IPCC assessment provides several scenarios
for the projected
Δ
Δ
T
for our planet (Figure 6.45). A rise in surface temperature can
lead to changes in ocean levels. Thus areas could be flooded and islands and coastal
plains can disappear. Regions that are presently the food baskets of the world can be
hit with severe drought, and agricultural production will be curtailed in those regions.
At the same time semi-arid regions of the world may become more conducive to agri-
culture. Attendant possibilities of international conflicts exist. If we are to mitigate
these likely effects, international cooperation and strong leadership are necessary to
curtail the emissions of CO
2
and other GHG.
Δ
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