He. Wright, GLOBAL CLIMATIC CHANGES SINCE THE LAST GLACIAL MAXIMUM - EVIDENCE FROM PALEOLIMNOLOGY AND PALEOCLIMATE MODELING, Journal of paleolimnology, 15(2), 1996, pp. 119-127
Recognition that Earth/Sun orbital changes are the basic cause for Qua
ternary climatic variations provides a context for explaining global e
nvironmental changes, many of which are preserved in the stratigraphic
and geomorphic record of lakes. Paleoclimatic numerical models sugges
t the mechanisms. In subtropical latitudes such as North Africa the en
hanced summer insolation culminating about 10 000 years ago resulted i
n the increased monsoonal rains that explain the widespread expansion
of lakes in now-desert basins. But in the American Southwest lake expa
nsion dates to 18 000-15 000 years ago, when storm tracks were displac
ed to the south by the ice sheets - themselves a product of earlier or
bital changes. The dynamics in the response of different components of
the natural system to climatic change are recorded in the stratigraph
y of lake sediments, not only by their pollen content as a manifestati
on of the regional vegetation but also by their microfossils and chemi
cal composition as reflections of lake development.