Climate Change — Definition

Definition

Climate change refers to significant and lasting changes in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It encompasses both global warming, which is the long-term heating of Earth's climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth's atmosphere, and its effects.

While 'global warming' specifically describes the increase in Earth's average surface temperature, 'climate change' is a broader term that includes global warming and everything else that is changing with the increase in greenhouse gases, such as sea level rise, melting glaciers, changes in precipitation patterns, and more frequent extreme weather events.

The primary driver of contemporary climate change is the enhanced greenhouse effect. Earth's atmosphere naturally contains gases like water vapour, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) that trap some of the sun's energy, preventing it from escaping back into space.

This natural greenhouse effect is vital for life on Earth, keeping our planet warm enough to sustain ecosystems. Without it, Earth's average temperature would be around -18°C, making it uninhabitable.

However, human activities, particularly the burning of fossil fuels (coal, oil, and natural gas) for energy, industrial processes, and transportation, have dramatically increased the concentration of these greenhouse gases in the atmosphere since the Industrial Revolution.

Deforestation also contributes significantly, as trees absorb CO2, and their removal releases stored carbon back into the atmosphere.

This excess accumulation of greenhouse gases acts like a thicker blanket around the Earth, trapping more heat and leading to a rise in global average temperatures. This warming then triggers a cascade of interconnected changes across the planet's systems.

For instance, rising temperatures cause glaciers and ice sheets to melt at an accelerated rate, contributing to sea-level rise. Warmer oceans expand, further exacerbating sea-level rise and increasing the frequency and intensity of marine heatwaves, which harm coral reefs and marine life.

Changes in temperature and precipitation patterns disrupt agricultural cycles, impact water availability, and increase the risk of extreme weather events such as heatwaves, droughts, floods, and severe storms.

Understanding climate change for the UPSC examination requires grasping these fundamental scientific principles, recognizing the anthropogenic drivers, and analyzing the multifaceted impacts across environmental, social, and economic spheres.

It also necessitates a deep dive into national and international policy responses, including mitigation strategies (reducing greenhouse gas emissions) and adaptation measures (adjusting to the impacts of climate change).

From a UPSC perspective, the critical examination angle here is not just knowing the facts, but understanding the interconnectedness of these phenomena and the policy challenges involved in addressing a global crisis that demands collective action while respecting national development priorities.