Geoscience Reference
In-Depth Information
Fig. 7.7
Interdecadal to centennial variability in temperature-sensitive series from Gulf of Alaska
(
red line
), northern Patagonia (
blue line
), and Raratonga (
brown line
), isolated by using singular
mean frequencies longer than 20 years were summed.
Thin
and
thick arrows
indicate coincidences
in oscillations between the Raratonga and one or two high-latitude records, respectively
Pacific records indicate that some of the interdecadal transitions in coral Sr/Ca
temporally align with comparable transitions in the Gulf of Alaska and north-
ern Patagonia temperature reconstructions. The remarkable shift in tropical Pacific
climate during the mid-1970s is clearly captured by all three records. However,
some differences are observed between interdecadal oscillations in the subtropical
coral and the North and South American tree-ring records. Interdecadal tempera-
ture oscillations in northern Patagonia closely align with transitions in the Pacific
coral Sr/Ca records from the 1850s to the beginning of the twentieth century,
whereas the Gulf of Alaska oscillations align better with Rarotonga Sr/Ca during
the second half of the twentieth century.
7.3.1.3 High-Latitude Oscillations
the Northern and Southern Hemispheres are also related to changes in the NAM
and sub-Antarctic regions, which in turn might provide insight on common forc-
ings of high-latitude past climates in both hemispheres. Boreal tree-ring records
from high latitudes in the Northern Hemisphere were used to provide a long-term
struction was based on 12 chronologies from North America: 3 in Alaska north
of 67
◦
N, 4 in northwestern-central Canada from the Yukon to Churchill, and 5
in eastern Canada. This sub-Arctic network was complemented with five boreal
