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Chapter Three Impacts of Global Climate Change

indicate that even if all greenhouse gas emissions were immediately halted, global tempera-
tures would remain elevated for some time due to accumulated atmospheric greenhouse gas-
es and the thermal inertia of Earth systems like oceans, potentially continuing to rise to some
extent. This means climate change impacts triggered by temperature rise - such as glacier
melting and sea-level rise - will persist and prove difficult to reverse. Taking glacier melt-
ing as an example, global glaciers have experienced accelerated melting over the past few
decades. Large ice sheets like those in Greenland and Antarctica, once their melting reaches
certain thresholds, will undergo self-reinforcing acceleration due to their own gravity and
topographical changes - a process that is essentially irreversible. Massive volumes of glacial
meltwater entering oceans drive sea-level rise, threatening the safety of coastal populations
and infrastructure.
Alterations in precipitation patterns also manifest the irreversibility of climate change.
Global warming has induced changes in atmospheric circulation patterns, subsequently
modifying global precipitation regimes. Some regions experience significantly increased
rainfall, triggering frequent flood disasters, while others face reduced precipitation and se-
vere droughts. Once established, such shifts in precipitation patterns are difficult to restore to
their original state within short timeframes. Taking the Sahel region of Africa as an example:
long-term climate change impacts have caused persistent precipitation reduction, intensified
droughts, and severe land desertification. Even with potential future climate improvements,
the local ecosystem’s severe degradation - manifested through decreased vegetation cover-
age and diminished soil water retention capacity - makes restoration of historical relatively
humid precipitation patterns nearly impossible, further exacerbating ecological deterioration
and socioeconomic challenges in the region.
Ocean acidification is a prominent manifestation of the irreversible nature of climate
change in marine ecosystems. The massive amounts of carbon dioxide emitted by human ac-
tivities are absorbed by the oceans, leading to a decrease in seawater pH value and triggering
ocean acidification. This poses severe threats to numerous marine organisms, particularly
those relying on calcium carbonate to build shells or skeletons, such as corals and shellfish.
Coral reef ecosystems are extremely sensitive to ocean acidification. When seawater pH
drops below certain thresholds, the growth and recovery capabilities of coral reefs become
inhibited, coral bleaching intensifies, and massive coral die-offs occur. As crucial habitats for
marine life, the destruction of coral reefs will trigger chain reactions affecting the structure
and function of entire marine ecosystems. Moreover, the ocean acidification process is rela-
tively slow yet persistent, and under current technological and emission levels, it is difficult
to reverse in the short term, with its impacts on marine ecosystems continuing to be profound
and long-lasting.

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