Global Climate Change — Definition
Definition
Global climate change refers to long-term shifts in temperatures and weather patterns across the planet, primarily driven by human activities since the Industrial Revolution. To understand this, it's crucial to differentiate between 'weather' and 'climate'.
Weather describes atmospheric conditions over short periods and small areas, like a daily forecast. Climate, on the other hand, represents the average weather patterns over a long period (typically 30 years or more) and across larger regions.
When we talk about climate change, we are observing significant, lasting alterations to these long-term averages.
The fundamental mechanism behind current climate change is the 'greenhouse effect'. Naturally, certain gases in Earth's atmosphere, known as greenhouse gases (GHGs) – such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapour – trap some of the sun's heat, preventing it from escaping back into space.
This natural process 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 have dramatically increased the concentration of these GHGs in the atmosphere.
Since the mid-18th century, the burning of fossil fuels (coal, oil, and natural gas) for energy, industrial processes, transportation, and electricity generation has released vast quantities of CO2. Deforestation, particularly in tropical regions, further exacerbates the problem because trees absorb CO2, and their removal releases stored carbon back into the atmosphere.
Agricultural practices, such as livestock farming and the use of nitrogen-based fertilizers, contribute significantly to methane and nitrous oxide emissions, respectively. These elevated concentrations of GHGs act like a thicker blanket around the Earth, trapping more heat and leading to a phenomenon known as 'global warming' – the long-term heating of Earth's climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities.
Global warming is a component of the broader term 'global climate change'. While global warming specifically refers to the rise in global average temperatures, climate change encompasses a wider range of observed changes, including sea-level rise, melting glaciers and ice sheets, changes in precipitation patterns (leading to more intense droughts or floods), ocean acidification, and an increase in the frequency and intensity of extreme weather events like heatwaves, storms, and wildfires.
These changes have profound impacts on natural ecosystems, biodiversity, human health, food security, water resources, and socio-economic stability worldwide. Addressing global climate change requires a concerted global effort to reduce GHG emissions (mitigation) and adapt to the unavoidable impacts already underway.