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Chapter Three Impacts of Global Climate Change

Chapter Three Impacts of Global Climate
Change

Section One Effects of Global Climate Change on
Ecosystems

Global climate change has extensive impacts on ecosystems, including changes in spe-
cies distribution, loss of biodiversity, and impairment of ecosystem service functions. These
changes not only threaten the balance of nature but also pose challenges to the sustainable
development of human society.

I. Changes in Species Distribution

As the climate warms, many species are forced to migrate toward polar regions or high-
er altitudes to seek suitable habitats. This phenomenon is widespread globally and has pro-
found impacts on the structure and function of ecosystems.
(1) Rising Temperatures Drive Species Migration
Temperature is one of the key factors determining habitat selection for flora and fauna.
When the average temperature in an area exceeds the adaptive range of species, they will
gradually migrate towards cooler areas. For instance, in the Northern Hemisphere, many
temperate forest tree species are expanding their distribution northward into areas originally
dominated by boreal coniferous forests. Similarly, alpine plants are continuously ascending
and colonizing higher mountain zones. However, such migrations are not always smooth, as
species in new environments may face new competitive pressures, predation risks, and dis-
ease threats.
(B) Response of Marine Organisms
Marine ecological systems similarlySignificant changes in species distribution have
been observed. With rising sea temperatures, some fish species in tropical and subtropical
waters have begun expanding into temperate and even polar regions. For instance, cod pop-
ulations in the North Atlantic have notably shifted northward over recent decades, leading
to declines in traditional fishing grounds. Additionally, frequent coral bleaching events are
forcing numerous marine organisms dependent on reefs to seek new habitats. For species
unable to adapt quickly to environmental changes, this may result in local extinction or sharp
population declines.
(III) Changes in Ecosystem Internal Relationships
Changes in species distribution not only affect the fate of individual species but also
alter the internal relationships within entire ecosystems. Each link in the food chain is inter-

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