518
Lea et a!.
a
0.2
1.4
0
1.2
"0' -0.2
P
~
co -0.4
0.8 ~
'"
0"
(,0
-0.6
0.6 a:
CD
~
(J)
0
-0.8
0.4 O' !..
iii
0'
0
> -1
0.2 ~
~
-1.2
0
-1.4
-0.2
0
20
40
60
80
100 120 140 160
Age, ka
b
I -- RC11·83 N. pachyderma I
0.5
0.5 :z
"0'
"0
~
I))
(")
",0
0
0 :::r
'<
~(,O
Q.
CD
....
~ -0.5
3
-0.5 I))
iii
O?
0
cr
>
-1
-1 ~
~
-1.5
-1.5
0
20
40
60
80
100 120 140 160
Age,ka
Fig. 3. Comparison of 8"C anomalies computed from the Vostok pCO, record with planktic 8"C records from South
Atlantic core RC 11-83 (42°S; IDoE; 4718m)(Charles et a!. 1996). Carbonate ion anomalies are computed from the
Vostok pCO, record relative to a baseline pCO, level of280 ppmV, assuming pCO, reductions were attained by
CaC0 3 addition. The calculations assume surface water-atmosphere equilibrium and a sea surface temperature of
IDOC. Vostok tJ.8"C values are computed from the carbonate anomalies using the experimental response for G.
bulloides. Note that the minimum at 42 kyr derives from a pCO, minimum in the original Vostok record that is less
pronounced in later records (Jouzel et a!. 1993). The isotope data from RCII-83 has been smoothed by a locally
weighted least squared error method to facilitate comparison. For both plots the Vostok and RCll-83 8"C scales
are matched in magnitude. (a) The negative shift in G. bulloid.es 8"C matches the magnitude of the calculated 8"C
values computed from the Vostok record. (b) The negative shift in N pachyderm a 8"C exceeds the magnitude of
the Vostock tJ.8"C values calculated using the response for G. bulloides.