Page 18 - 全球气候变化及其影响Global Climate Change and Its Impacts-185×260

Global Climate Change and Its Impacts

ed into the atmosphere. These particles spread in the stratosphere, forming a suspended aero-
sol layer. Sulfide particles (such as sulfur dioxide) react with water vapor in the stratosphere
to form sulfuric acid droplets, which can reflect solar radiation, thereby reducing the amount
of sunlight reaching the Earth’s surface. This reflective phenomenon is known as the “Parasol
Effect,” capable of significantly lowering global surface temperatures for months or even
years after an eruption. For example, the 1991 eruption of Mount Pinatubo in the Philippines
injectedreleased approximately 20 million tons of sulfur dioxide, resulting in a decrease of
approximately 0.5°C in global average temperatures over the following two years. This phe-
nomenon demonstrates that particulate matter released by volcanic eruptions can produce
significant short-term cooling effects on global climate.
In addition to particulate matter, volcanic eruptions also release large amounts of green-
house gases such as carbon dioxide and water vapor. Although the atmospheric concen-
trations of these gases are significantly lower than those emitted by human activities, they
still exert certain influences on global climate. The carbon dioxide released from volcanic
eruptions mainly originates from carbonate rocks in the crust and dissolved gases in magma.
While volcanic CO emissions are relatively small compared to human activities (such as
2
fossil fuel combustion), they still contribute to atmospheric carbon dioxide concentrations.
For instance, global volcanic activity emits approximately 20 million tons of CO annually,
2
whereas human activities emit about 40 billion tons each year. However, the climate impact
of volcanic CO emissions is typically overshadowed by the cooling effects of particulate
2
matter released during eruptions.
The impact of volcanic activity on climate is not only manifested in short-term effects
but may also indirectly influence global climate through long-term geological processes.
For example, carbon dioxide and other greenhouse gases released by volcanic eruptions
may gradually accumulate over hundreds or even thousands of years, thereby exerting long-
term effects on global climate. Additionally, volcanic eruptions may influence marine carbon
cycles and biochemical processes by altering the chemical composition and pH balance of
oceans. For instance, carbon dioxide released from volcanic eruptions can increase ocean
acidity, thereby affecting marine organisms’ calcification processes and ecosystem stability.
The impact of volcanic activity on climate is also manifested in its alteration of atmo-
spheric circulation patterns. Volcanic eruptions release particles and gases that can alter the
optical and thermodynamic properties of the atmosphere, thereby influencing atmospheric
circulation patterns. For example, sulfide particles released by volcanic eruptions can form
an aerosol layer in the stratosphere. This aerosol layer reflects solar radiation, reducing the
amount of solar radiation reaching the Earth’s surface and consequently lowering surface
temperatures. This cooling effect can modify temperature gradients in the atmosphere, which
in turn affects atmospheric circulation patterns. For instance, post-eruption cooling effects
may strengthen polar vortices and weaken mid-latitude westerly jet streams, thereby influ-
encing global weather patterns and precipitation distribution.

• 10 •