Geoscience Reference
In-Depth Information
Fig. 7.8
Temperature reconstructions from Arctic and sub-Antarctic regions. The geographical
locations of tree-ring chronologies (
red triangles
) used for developing the temperature reconstruc-
tions for the Arctic (
left
) and sub-Antarctic (
right
) regions are shown. See text for reconstruction
details
tree-ring chronologies from Scandinavia (67
◦
−
69
◦
N) and three from the northern
by the tree-ring chronologies during the 1880-1969 calibration period is 66%. The
major low-frequency trends in the reconstructed Arctic temperature
s
include a cool-
ing in the late 1600s to early 1700s, a relative warming in the 1700s, an abrupt
decline in temperature in the early 1800s, a gradual warming since the middle to
late 1800s, and unprecedented warming during the twentieth century. Recently, a
new reconstruction of temperature variability for the Arctic has been developed
with significantly improved geographical coverage and replication than previously
(Gordon Jacoby, in preparation). The new temperature record reproduces most
climatic events previously reconstructed, reinforcing the occurrence of major tem-
perature changes in the sub-Arctic during the past four centuries. For comparison
with the sub-Antarctic temperatures, the two reconstructions were averaged in a
single Arctic temperature record.
The northern latitude record was compared with the temperature reconstructions
interval 1670-1987, the correlation coefficient between the Arctic and sub-Antarctic
(average of the two southern reconstructions) is
r
0.001). For the
past 400 years, striking similarities in temperature fluctuations are observed in both
regions. The records exhibit their largest common variances at low frequencies
=
0.55 (
p
<
