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Global Climate Change and Its Impacts

From the perspective of climate change rates, it can be clearly divided into slow change
phases and rapid change phases. During slow change phases, the evolution of the climate
system maintains relative stability, with critical climate indicators such as temperature and
precipitation demonstrating extremely small variations over extended time scales. Typical-
ly spanning decades or even centuries, the climatic trends during this phase show minimal
short-term significance. For instance, during the extensive pre-industrial period of human
history, global climate remained in a relatively stable slow change phase. Although minor cli-
mate fluctuations occurred during this era - such as the Medieval Warm Period (approximately
950 to 1250 CE) when mid-to-high latitude regions in the Northern Hemisphere experienced
temperature increases that boosted agricultural productivity in some areas, and the Little
Ice Age lasting from the 13th century to the 19th century that brought global temperature
declines impacting agriculture and human livelihoods - these fluctuations appear relatively
mild when viewed across multi-century timescales. The primary drivers behind this pattern
stem from natural climate system adjustments: the ultra-slow variations in Earth’s orbital
parameters (eccentricity, axial tilt, and precession) with cycles spanning tens to hundreds of
millennia; subtle fluctuations in solar radiation intensity caused by periodic solar activity;
and low-frequency oscillations in ocean-atmosphere systems like the Pacific Decadal Oscil-
lation (PDO) and Atlantic Multidecadal Oscillation (AMO) with multi-decadal cycles. These
natural factors with prolonged variation cycles induce correspondingly sluggish responses in
the climate system, thereby manifesting distinct slow-change characteristics.
In stark contrast, the climate change velocity during the rapid change phase shows sig-
nificantly accelerated momentum, with various climate indicators undergoing dramatic alter-
ations within relatively short timeframes. Since the Industrial Revolution, the intensification
and expansion of human activities have emerged as the pivotal driving force propelling cli-
mate change into this accelerated phase. The massive combustion of fossil fuels—including
coal, petroleum, and natural gas—has caused a steep surge in greenhouse gas emissions (par-
ticularly carbon dioxide), consequently triggering rapid global temperature escalation. Scien-
tific research data reveals that global average temperatures have risen approximately 1.1°C
since the late 19th century, a warming rate that far exceeds the average variation pace ob-
served over previous millennia. This rapid change phase has witnessed numerous landmark
events: since the 1980s, extreme heatwaves have become increasingly frequent worldwide,
exemplified by Europe’s 2019 record-breaking temperatures that posed severe health and
livelihood threats; concurrent Arctic sea ice extent has dramatically shrunk in recent decades,
with satellite data showing successive summer minimums reaching historic lows—pro-
foundly impacting Arctic ecosystems, ocean circulation patterns, and global climate systems.
These phenomena conclusively demonstrate that the climate system is undergoing unprec-
edented rapid transformations, where anthropogenic influences have decisively surpassed
natural variability to become the dominant force shaping contemporary climate change.
The magnitude of climate change is also one of the important bases for dividing dif-

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