Warming

Warming refers to an increase in temperature. In climate science, it most often concerns the Earth's average surface temperature or regional temperature trends. Warming can arise from increased energy input or decreased energy loss. The dominant modern driver is the enhanced greenhouse effect: higher concentrations of greenhouse gases trap more infrared radiation. Feedbacks involving clouds, water vapor, ice, and land-use changes can amplify or dampen warming.

Global warming describes the long-term rise in Earth's average surface temperature since the late 19th century. Temperature is reported as anomalies relative to a baseline. The global average surface temperature has risen by about 1.0 to 1.2 degrees Celsius since 1880, with most warming since the 1970s. Warming is geographically uneven, and the upper layers of the ocean have absorbed most of the excess heat.

Evidence includes instrumental records, paleoclimate proxies, shrinking Arctic sea ice, glacier retreat, and rising ocean heat content. Warming influences the climate system, contributing to more intense heat extremes, heavier rainfall in some regions, sea level rise from thermal expansion and ice loss, and ecological changes that affect biodiversity and agriculture.

Responses emphasize mitigation—reducing greenhouse gas emissions and enhancing sinks—and adaptation—preparing for climate impacts. Policy frameworks such as the United Nations Framework Convention on Climate Change guide international efforts. Warming is a central focus of climate science and informs decisions in energy, infrastructure, and risk management.