What Is Climate Change
Last updated: March 31, 2026
Key Facts
- Earth's average temperature has risen approximately 1.1°C (2°F) since the pre-industrial era
- Carbon dioxide levels are at their highest in at least 800,000 years, exceeding 420 parts per million
- The last decade (2014–2023) was the warmest on record
- 97% of actively publishing climate scientists agree that human activities are causing global warming
- The Paris Agreement aims to limit warming to 1.5°C above pre-industrial levels
Overview
Climate change is the defining environmental challenge of our time. It refers not just to rising temperatures but to a cascade of interconnected changes: melting ice sheets, rising sea levels, more frequent extreme weather events, shifting ecosystems, and ocean acidification. While Earth's climate has changed naturally throughout its 4.5-billion-year history, the current rate of change is unprecedented.
The Greenhouse Effect
The greenhouse effect itself is natural and essential — without it, Earth's average temperature would be about -18°C (0°F) instead of the habitable 15°C (59°F). The problem is that human activities have intensified this effect by dramatically increasing the concentration of greenhouse gases:
- Carbon dioxide (CO₂): From burning fossil fuels (coal, oil, natural gas) and deforestation — responsible for about 75% of warming
- Methane (CH₄): From agriculture (livestock, rice paddies), landfills, and natural gas leaks — about 16% of warming
- Nitrous oxide (N₂O): From agricultural fertilizers and industrial processes
Observed Effects
Global average sea levels have risen about 20 cm (8 inches) since 1900 and the rate is accelerating. Arctic sea ice is declining by about 13% per decade. Extreme weather events — heatwaves, droughts, intense hurricanes — are becoming more frequent and severe. Coral reefs are experiencing mass bleaching events. Many species are shifting their ranges toward the poles or to higher elevations.
What Can Be Done
Mitigation involves reducing greenhouse gas emissions through renewable energy, energy efficiency, electrification of transport, and protecting forests. Adaptation involves preparing for the changes already locked in — building sea walls, developing drought-resistant crops, and improving early warning systems for extreme weather.
Related Questions
What is the difference between climate change and global warming?
Global warming refers specifically to the rise in Earth's average surface temperature. Climate change is a broader term that includes global warming plus all the related effects: changing rainfall patterns, more extreme weather, rising sea levels, and shifting ecosystems.
Is climate change reversible?
Some effects of climate change are already irreversible on human timescales — ice sheet loss, species extinction, and sea level rise will continue for centuries. However, reducing emissions can slow the rate of change and prevent the worst projected outcomes. Carbon removal technologies may eventually help draw down atmospheric CO₂.
How does climate change affect me personally?
Climate change affects daily life through more extreme heat events, increased food prices from crop disruptions, higher insurance costs in flood and fire-prone areas, worsening air quality, increased allergy seasons, and potential displacement from rising sea levels or extreme weather.
Sources
- Wikipedia — Climate Change CC-BY-SA-4.0
- NASA — Climate Change: Vital Signs of the Planet public_domain