Global Warming

Summary

The long-term rise in global average temperature caused mainly by human emission of greenhouse gases.

In depth

Global average temperature has risen about 1.1 to 1.2 °C since pre-industrial times. Evidence: temperature records, sea level rise, glacier retreat and ocean heat content. Impacts include more extreme weather. The Paris Agreement aims to limit warming to well below 2 °C.

Climate change differs from weather. Attribution studies link events to warming. Mitigation reduces emissions; adaptation prepares for impacts.

Key idea: scientific consensus attributes recent warming to human activity.

Global warming is the long-term rise in average surface temperature, about 1.1 to 1.2 °C above pre-industrial levels by the early 2020s, caused mainly by burning fossil fuels, deforestation and agriculture. Evidence includes thermometer records, shrinking glaciers and sea ice, rising seas, ocean heat content and shifts in species ranges and seasons.

Impacts include more extreme heat, drought, heavy rainfall and wildfire, coral bleaching and ocean acidification. The Paris Agreement aims to hold warming well below 2 °C, ideally 1.5 °C, requiring deep cuts in emissions and net zero around mid-century.

Example: Arctic sea ice has declined by about 13 percent per decade in summer.