Environmental Engineering Reference
In-Depth Information
320
310
300
290
C
S
280
C
S
270
260
250
+15
C temperature increase
relative to 1 x CO
2
SSTs
+8
C temperature increase
relative to 1 x CO
2
SSTs
240
90
N
45
N
N
Latitude
0
45
S
90
S
Figure 20.2 Zonal mean sea-surface temperatures (SSTs) as a function of CO
2
levels and latitude. KS2005 denotes simulations from Kiehl and Shields (
2005
).
CCSM3 runs were completed with Community Climate System Model 3;
CCSM4 runs were completed with Community Climate System Model 4. Based
on oxygen isotope records from conodonts, Joachimski
et al
.(
2012
) report a
þ
8
Cwarming of low-latitude sea-surface temperatures across the Permian
Triassic
-
15
C warming of low-latitude sea-surface
temperatures from the middle Permian up to the Middle Triassic. For reference,
both potential temperature increases are shown here, relative to a simulation
of Permian climate with 1
boundary; Sun
et al
.(
2012
)reporta
þ
present-day CO
2
(355 ppm). Temperatures below
1.8
C (271.3 K) correspond to sea-ice.
-
increase in CO
2
leads to a zonally averaged low-latitude sea-surface temperature
increase that is highly consistent with the
þ
8
˚
C warming reported by Joachimski
et al
.(
2012
).
A
þ
15
˚
C warming of the equatorial sea surface (Sun
et al
.,
2012
) is more
dif
cult to achieve, and exceeds the temperature increase associated with a ten-fold
increase in CO
2
to 3550 ppm (Kiehl and Shields,
2005
). Based on a survey of
climate models, an approximately 2
-
4
C global temperature increase is expected
for each doubling of CO
2
(Rohling
et al
.,
2012
). The magnitude of the long-term
warming reported by Sun
et al
.(
2012
) thus requires higher climate sensitivity,
extreme CO
2
levels or large quantities of other greenhouse gases (such as CH
4
)in
addition to CO
2
.
20.6 Global cooling
Stratospheric volcanic emissions of short-lived sulfur gas could produce transient
aerosol-induced cold spells within a long-term greenhouse warming trend from
longer-lived CO
2
. The eruption of the Siberian Traps occurred at relatively high
