Causes of climate change
Topic: Climate Change: Causes, Evidence and the Global Response · NCERT: Class 11, Ch 11 "World Climate and Climate Change"
Meaning
The causes of climate change fall into two groups. Astronomical causes come from space. They include changes in the Sun's output, which rise and fall with sunspots, and Milankovitch cycles, which are slow changes in Earth's orbit and axis. Terrestrial causes come from the Earth itself. They include volcanism and, most importantly, the human-caused rise in greenhouse gases. Natural causes explain ice ages and short cool spells. Only greenhouse gases explain the warming since the industrial era.
Example
Since 1950 the Sun's output has been flat or slightly falling, yet global temperatures have kept rising. In 2024 the world was about 1.55 °C warmer than before industry, according to the WMO (World Meteorological Organization). This shows the Sun is not the cause, and points to human emissions. Volcanoes emit well under 1% as much CO2 as humans.
Don't confuse with
- Climate variability: short-term ups and downs, such as a single drought or flood year. Climate change is a long-term shift in average weather.