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Global Climate Change and Its Impacts

II. Alternating Intense Rainfall and Drought

(1) Drivers of Precipitation Pattern Changes
Climate change is the primary driver behind significant alterations in precipitation pat-
terns. As global temperatures rise, the atmosphere can hold more water vapor, leading to
more frequent and intense extreme precipitation events. Research indicates that for every
1°C temperature increase, atmospheric water vapor content rises by approximately 7%. This
means that under warming climate conditions, both the frequency and intensity of heavy
rainfall and other extreme precipitation events have increased. Meanwhile, natural climate
variability systems – such as the El Niño-Southern Oscillation (ENSO) and the North At-
lantic Oscillation (NAO) – continue to modulate precipitation distribution across different
temporal and spatial scales. These natural oscillation patterns interact synergistically with
anthropogenic factors, modifying regional hydrological cycles and elevating the probability
of extreme weather events.
Furthermore, urbanization and land use changes have also significantly impacted pre-
cipitation patterns. During urban expansion, vast green spaces are covered with concrete and
asphalt, creating a heat island effect and altering local climatic conditions. The heat island
effect causes urban centers to have higher temperatures than surrounding rural areas, pro-
moting localized convective activity and increasing the likelihood of short-duration heavy
rainfall. Meanwhile, large-scale land reclamation and deforestation have reduced vegetation
coverage, weakened the soil’s water retention capacity, and further exacerbated water scarci-
ty in arid regions.
(II) Impact of Flood Disasters
In some regions, precipitation is concentrated and extremely intense, with large amounts
of rainfall occurring within short periods that exceed local drainage systems and river capac-
ities, leading to floods. For example, the South Asian subcontinent experiences severe flood-
ing disasters annually during monsoon seasons, resulting in massive casualties and property
damage. According to United Nations data, the 2023 floods in India and Bangladesh affected
over 40 million people, causing economic losses amounting to billions of US dollars. Ac-
celerated urbanization,Non-permeable surfaces have increased, further exacerbating surface
runoff velocity, reducing rainwater infiltration time, and making urban areas more vulnerable
to flood inundation. Additionally, geological hazards such as mountain debris flows and land-
slides often accompany torrential rains, threatening resident safety and infrastructure.
Flood disasters not only cause direct damage to human life but also have long-term
impacts on ecosystems. Floods inundate farmland, destroy crop growth, leading to reduced
grain production; submerge wetlands and river ecosystems, affecting biodiversity. In the
long term, frequent flood disasters alter river morphology, exacerbate riverbank erosion, and
affect the stability of hydrological environments. For example, the middle and lower reaches
of the Yangtze River have been repeatedly hit by floods in recent years, severely affecting
the health and development of local ecosystems.

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