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Global Climate Change and Its Impacts

sorbing and releasing carbon dioxide. For example, forests serve as significant carbon sinks,
capable of absorbing large amounts of CO ; whereas deforestation and land degradationre-
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lease carboninto the atmosphere, becoming carbon sources.
2.Greenhouse Gas Emissions and Absorption
Beyond carbon dioxide, biogeochemical cycles also involve the emission and absorp-
tion of other greenhouse gases, such as methane (CH ) and nitrous oxide (N O). For instance,
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wetlands and ruminants are major sources of methane, while microorganisms in oceans and
soils release nitrous oxide through decomposition processes.
3.Feedback Mechanisms
Biogeochemical cycles and the climate system exhibit complex feedback mechanisms.
For example, global warming may lead to permafrost thawing, releasing vast amounts of
methane and carbon dioxide, further exacerbating climate change.
(4) Human Activities’ Impact on Biogeochemical Cycles
Human interference in biogeochemical cycles is one of the key drivers of current cli-
mate change. Below are several major impacts:
1.Deforestation and Land Use Changes
Deforestation and land use changes (e.g., agricultural expansion and urbanization) sig-
nificantly reduce terrestrial ecosystems’ carbon sequestration capacity while releasing sub-
stantial carbon into the atmosphere. For instance, tropical rainforest deforestation results in
billions of tons of carbon dioxide emissions annually.
2.Ocean Acidification
Ocean absorption of atmospheric carbon dioxide causes seawater acidification, subse-
quently affecting marine ecosystem health. Acidified seawater inhibits coral and shellfish
growth, disrupts marine food chains, and reduces oceanic carbon absorption capacity.
3.Excessive Nitrogen Input
Fertilizer use and industrial nitrogen fixation lead to excessive nitrogen inputs, causing
water eutrophication and increased greenhouse gas emissions. For example, nitrous oxide is
a potent greenhouse gas, and itsemissions due to nitrogenoverloading have significantly in-
creased.
4.Feedback Effects of Climate Change on Biogeochemical Cycles
Climate change itself also influences biogeochemical cycles. For example, global
warming may increase forest fire frequency, further elevating CO emissions; meanwhile,
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climate change could alter plant growth cycles and soil microbial activity, affecting carbon
and nitrogen cycling.
(V) Interactions Between Biogeochemical Cycles and Other Natural Drivers
Biogeochemical cycles interact with other natural drivers (e.g., volcanic activity, solar
radiation variations) to shape Earth’s climatic characteristics. For example:
1.Volcanic Activity
Volcanic eruptions release large amounts of carbon dioxide and sulfides into the atmo-

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