Climate Change
Climate change refers to long-term shifts in global and regional climate patterns, including changes in temperature, precipitation, wind patterns, and the frequency of extreme weather events, driven largely by human activities since the mid-20th century. While Earth's climate has always varied naturally due to orbital cycles, volcanic eruptions, and solar variability, the current rate and magnitude of change are unprecedented in the geological record of the past 800,000 years. The primary driver is the increased atmospheric concentration of greenhouse gases from burning fossil fuels, deforestation, and agricultural practices.
Observed Impacts of Climate Change Across Systems
| System | Observed Change | Trend (2024) | Primary Driver |
|---|---|---|---|
| Global Mean Temperature | +1.2°C above pre-industrial | Rising | CO₂ and CH₄ emissions |
| Arctic Sea Ice | −13% per decade since 1979 | Declining | Polar amplification |
| Sea Level | +20 cm since 1900 | Rising 3.7 mm/yr | Ice melt and thermal expansion |
| Ocean Acidity | pH dropped from 8.2 to 8.1 | Increasing acidity | Oceanic CO₂ absorption |
| Extreme Heat Events | More frequent and intense | Increasing | Higher mean temperatures |
| Glacier Volume | ~50% reduction since 1900 | Declining | Rising temperatures |
Interactive Tools
PhET Greenhouse Effect Simulation
Explore how greenhouse gas changes affect Earth's energy balance
Open ToolKhan Academy – Climate Change
Comprehensive course on climate change causes, evidence, and policy
Open ToolBrilliant.org Earth Science
Interactive problem-solving covering climate systems and atmospheric science
Open Tool
Wikimedia Commons, CC BY-SA
Related Terms
Global Warming
Global warming refers to the long-term increase in Earth's average surface temperature, primarily caused by the enhanced greenhouse effect resulting from human-induced emissions of greenhouse gases such as carbon dioxide, methane, and nitrous oxide. Since the pre-industrial era (before 1850), global average temperatures have risen by approximately 1.2°C, with the rate of warming accelerating significantly since the mid-20th century. This warming drives profound changes in climate patterns, sea levels, ice cover, and biodiversity worldwide.
Greenhouse Effect
The greenhouse effect is the process by which certain gases in Earth's atmosphere — primarily water vapour, carbon dioxide, methane, and nitrous oxide — absorb and re-emit infrared radiation from the planet's surface, trapping heat and warming the lower atmosphere. This natural phenomenon is essential for life on Earth, raising the average surface temperature from a frigid −18°C (without greenhouse gases) to the current mean of approximately 15°C. Human activities that increase greenhouse gas concentrations enhance this effect, driving global warming and climate change.
El Niño
El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO), a periodic climate pattern involving anomalously warm sea surface temperatures in the central and eastern tropical Pacific Ocean that typically occurs every 2 to 7 years and lasts 9 to 12 months. This ocean–atmosphere interaction disrupts normal trade wind patterns, suppresses the cold upwelling of the Peruvian coast, and triggers widespread alterations in global precipitation and temperature distributions. El Niño events are associated with droughts in Australia and South Asia, flooding in South America and East Africa, and unusually warm global mean temperatures.
The term "climate change" was used as early as the 1950s in scientific literature. It gained prominence when the IPCC (Intergovernmental Panel on Climate Change) was established in 1988. "Climate" derives from Greek klima (inclination, region), referring to the angle of the sun, while "change" comes from Latin cambiare (to exchange or alter).