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Global Climate Change and Its Impacts

ularly since the end of the last glacial period, which marked the beginning of the Holocene
epoch around 12,000 years ago, global temperatures have gradually risen alongside increas-
ing atmospheric greenhouse gas concentrations.
(C) Fossil Records
Fossils serve as a crucial window into understanding past ecosystems and climatic en-
vironments. Plant fossils (such as pollen and spores) provide information about vegetation
distribution and types, thereby allowing inference of historical climate characteristics. For
instance, broadleaf forests typically dominate under warm and humid climatic conditions,
while coniferous forests or grasslands prevail in cold and arid environments. Animal fossils
also hold indicative significance, as their species, distribution ranges, and ecological habits
often reflect specific climatic conditions of particular periods. For example, mammoth and
other large mammal fossils indicate that during the last glacial period, northern Eurasia was
extensively covered by cold-adapted tundra and sparse forests.
(IV) Tree-Ring Chronology
Variations in tree-ring widthDirect responseto moisture availability during the grow-
ing season, temperature, and other environmental factors. By precisely measuring tree-ring
sequences, scientists can obtain high-resolution short-term climate records. Wood samples
from certain ancient trees or extinct tree species can extend back hundreds or even thousands
of years, forming continuous dendrochronological records. This method can not only be used
to calibrate other types of paleoclimate records but also reveal the frequency and intensity
of extreme climate events such as droughts and floods. For example, tree-ring studies of co-
niferous trees in the southwestern United States show that the region experienced multiple
severe prolonged drought periods during the past millennium, which had profound impacts
on local agriculture and social structures.
(5) Mineral Records
Some minerals also record ancient climate information. For example, stalagmites and
stalactites in caves formed by dripping water precipitation exhibit internal structures and
chemical compositions that reflect precipitation patterns and temperature changes during
their formation. By measuring uranium-thorium radioactive decay series elements in these
minerals, scientists can determine their ages and further analyze climatic conditions of that
period. Similarly, evaporites (e.g., gypsum, salt deposits) found along lake shores serve as
indicators formed in arid environments, whose presence suggests decreased precipitation
during specific periods.

II. Analysis of Ice Core Data

Ice core data is one of the important tools for studying past climate change. By ana-
lyzing the preserved air bubbles and chemical composition in ice cores, it reveals historical
atmospheric temperatures and composition. Ice cores are cylindrical ice samples drilled from
polar ice sheets or alpine glaciers, whose formation process records the deposition history

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