
The long-term average of weather conditions in a particular region.Climate is the long-term average of weather conditions—temperature, precipitation, humidity, wind patterns, and more—over decades to centuries in a particular region. Unlike weather, which fluctuates daily, climate captures the statistical baseline and variability that shape ecosystems, agriculture, and human civilization. It is not static: climate changes over geological timescales due to factors like orbital shifts, volcanic activity, and atmospheric composition, and more recently due to human influence.
The modern scientific understanding of climate began in the 19th century with Joseph Fourier's work on the greenhouse effect (1824) and Svante Arrhenius's calculations of CO2 warming (1896). Systematic climate observation and modeling expanded in the 20th century, leading to the establishment of the IPCC in 1988.
Climate is driven by the balance of incoming solar radiation and outgoing heat, modulated by greenhouse gases, clouds, oceans, and land surfaces. The atmosphere and oceans redistribute heat through currents and circulation patterns, creating regional climates. Feedback loops—such as ice-albedo (ice reflects sunlight, cooling the planet) and water vapor (warmer air holds more moisture, trapping more heat)—amplify or dampen changes. Climate models simulate these interactions using physical equations, from global circulation to cloud microphysics, to project future conditions.
Climate science informs policy on emissions reduction, urban planning, agriculture, and disaster preparedness, as well as engineering for infrastructure resilience to changing weather patterns.
The Earth's climate has swung between 'snowball Earth' states (nearly fully ice-covered) and greenhouse periods with no polar ice—all within the last billion years.























