Page 271 - Earth's Climate Past and Future

Melted ice (%) Sea ice diatoms (%) Advance Svalbard Retreat
0 50 100 50 40 30 20 10 0 glaciers
0 0 0

2000

Years ago 4000 14 C years ago 2000 14 C years ago 2000
4000
4000

6000 6000 6000
?
C
8000 B

A
120° 100° 80° 60° 40° 20° 0° 20° 40°

Northern forest limit Estimated sea surface
S km N temperature (°C)
100 0 100 200 300 6° 8° 10°
0 0
Modern
position

2000
14 C years ago 14 C years ago 2000

4000
? 4000

6000 6000
E

D
FIGURE 13-19 Cooling toward the present Evidence of a cooling of high northern latitudes during the last several thousand
years includes (A) less frequent summer melting episodes in ice caps on Arctic islands; (B) more frequent sea ice off Greenland;
(C) advances of ice caps on Arctic islands north of Europe; (D) lower temperatures in the Atlantic Ocean west of southern Norway;
(E) a southward shift of the boundary between tundra and spruce forest in northern Canada. (A: Adapted from R. M. Koerner and
D. A. Fisher, “A Record of Holocene Summer Climate from a Canadian High-Arctic Ice Core,” Nature 343 [1990]: 630–31; B and D:
adapted from N. Koc et al., “Paleoceanographic Reconstructions of Surface Ocean Conditions in the Greenland, Iceland, and
Norwegian Seas Through the Last 14 Ka Based on Diatoms,” Quaternary Science Reviews 12 [1992]: 115–40. C: Adapted from J.
Lubinski, S. L. Forman, and G. H. Miller, “Holocene Glacier and Climate Fluctuations on Franz Joseph Land, Arctic Russia,”
Quaternary Science Reviews 18 [1999]: 87–109. E: Adapted from H. Nichols, “Palynological and Paleoclimatic Study of the Late
Quaternary Displacement of the Boreal Forest-Tundra Ecotone in Keewatin and MacKenzie, N.W.T.,” Institute of Arctic and Alpine
Research Occasional Paper 15 [Boulder, CO, 1975].)

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