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Global Climate Change and Its Impacts

habitats or through adjustments in their physiological adaptation mechanisms. During this
phase, both ecosystems and human societies generally maintain relatively stable operational
states overall.
In the significant impact phase, the negative effects caused by climate change have
shown a markedly intensified trend, exceeding the existing adaptive capacity of both eco-
systems and human societies. Currently, with the continued development of global warming
trends, we are precisely in such a significant impact phase. During this stage, sea level rise
poses a serious threat to human habitation safety in coastal areas, with many low-lying island
nations such as Maldives and Tuvalu facing real risks of being submerged by seawater; the
frequency and intensity of extreme precipitation events continue to increase, frequently trig-
gering flood disasters that cause severe damage to infrastructure and greatly threaten human
life and property safety. For instance, the catastrophic rainstorm disaster that struck Henan
in 2021 resulted in severe flooding across multiple regions, with serious urban waterlogging
causing enormous losses to residents’ lives and properties; intensified drought phenomena
have led to significant reductions in crop yields, subsequently triggering food security crises.
In parts of Africa, prolonged droughts have caused complete crop failures, leaving large pop-
ulations facing starvation threats. Regarding ecosystems, numerous species are facing extinc-
tion crises due to their inability to adapt to rapidly changing climatic environments, leading
to severe biodiversity destruction. Taking Australia as an example, the frequent forest fires
in recent years are closely related to high-temperature drought weather caused by climate
change. The 2019-2020 Australian bushfires that burned for months destroyed vast areas of
forests, left countless wildlife homeless, and pushed many rare species to the brink of extinc-
tion, delivering near-devastating blows to local ecosystems. All these fully demonstrate that
climate change has already exerted enormous and hard-to-reverse profound impacts on both
ecosystems and human societies.
In practical scientific research, it is often necessary to comprehensively consider mul-
tiple factors such as the rate, magnitude, and impact degree of climate change to more accu-
rately delineate climate change phases. Through in-depth analysis of paleoclimate records
(e.g., climate information preserved in deep-sea sediments, ice cores, and tree rings); system-
atic review of historical documents recording climate phenomena, agricultural production,
and natural disasters; and integrated application of modern observational data (including
satellite remote sensing data, ground meteorological observations, and oceanographic data)
combined with advanced climate model simulations, researchers can more precisely deter-
mine the start/end times, key characteristics, and landmark events of different climate change
phases. This series of research efforts provides a solid foundation for understanding the his-
torical evolution of climate change, assessing current realities, and predicting future trends,
thereby helping humanity better address climate challenges.

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