Geoscience Reference
In-Depth Information
were not seen in the control run, they concluded that greenhouse gases and sulfate
aerosols may indeed have played a role.
As is seen in
Figure 1.5
and discussed in
Chapter 2
, warming over past sev-
eral decades, although largely global in its nature, has been larger in the Arctic as
compared to the global or Northern Hemisphere average. This Arctic amplification
appears to have several causes, including responses to reduced sea ice cover, altered
cloud cover, and changes in atmospheric circulation. As discussed in
Chapter 9
(see
Figure 9.15
) Arctic amplification is expected to more prominent through the
twenty-first century.
Focus Questions and Exercises
1) Why is it important to study paleoclimates?
2) Should the Younger Dryas be viewed as the last of the Dansgaard-Oeschger
cycles? List some arguments for and against this view.
3) Why have Dansgaard-Oeschger cycles not been observed during the
Holocene?
