Climate change
Climate change is the long-term shift in Earth's temperature, rainfall, oceans, ice, ecosystems, and extreme weather patterns, driven today mainly by human greenhouse gas emissions from fossil fuels, land use, agriculture, and industry.
What climate change means
Climate is the long-term pattern of weather in a place or across the planet. Climate change means those long-term patterns are shifting. The modern issue is not just that Earth has warmed; it is that warming is happening quickly because human activities have increased heat-trapping greenhouse gases. Climate change includes rising average temperatures, changing rainfall, warming oceans, melting ice, sea-level rise, ecosystem shifts, and more frequent or intense extremes in many regions.
Why the planet is warming
Earth stays warm because greenhouse gases such as carbon dioxide, methane, and nitrous oxide trap some outgoing heat. Human activities have strengthened this greenhouse effect by burning coal, oil, and gas, clearing forests, producing cement, raising livestock, and using some industrial chemicals. Carbon dioxide lasts a long time in the atmosphere, so total accumulated emissions matter. Methane is shorter-lived but powerful, so reducing it can slow near-term warming.
Evidence scientists use
Climate evidence comes from many independent sources. Thermometers and satellites show rising air and ocean temperatures. Ice cores record past greenhouse gas levels. Glaciers, Arctic sea ice, and ice sheets have been shrinking in many places. Sea level is rising as water warms and land ice melts. Oceans are storing most of the extra heat. Plants and animals are shifting ranges and seasonal timing. These patterns match what physics predicts from increased greenhouse gases and cannot be explained by the Sun alone.
Impacts already happening
Climate change is affecting heat waves, heavy rainfall, drought risk, wildfire weather, coastal flooding, crop stress, water supplies, coral reefs, disease ranges, and ecosystem health. Not every event is caused only by climate change, but warming changes the odds and intensity of many extremes. Impacts are uneven: people with fewer resources, outdoor workers, coastal communities, small islands, children, older adults, and communities already facing pollution or poverty often carry higher risks.
Why oceans and ice matter
The ocean absorbs most of the excess heat trapped by greenhouse gases and also takes up some carbon dioxide. That reduces warming in the air but creates ocean warming, acidification, oxygen loss, marine heat waves, and stress for ecosystems. Ice matters because bright snow and ice reflect sunlight, while darker ocean and land absorb more heat. Melting glaciers and ice sheets raise sea level, and thawing permafrost can release additional greenhouse gases.
Mitigation: reducing the cause
Mitigation means reducing greenhouse gas emissions and increasing carbon storage. Major strategies include clean electricity, renewable energy, nuclear power where used, electrified transport and heating, energy efficiency, low-carbon industry, methane reduction, forest and wetland protection, better land management, and cleaner fuels for hard-to-electrify sectors. The faster emissions fall, the more future warming and damage can be avoided.
Adaptation: reducing harm
Adaptation means preparing for impacts that are already happening or unavoidable. Examples include heat action plans, flood defenses, wildfire planning, drought-resistant crops, water conservation, early warning systems, stronger building codes, climate-informed insurance, coastal retreat where necessary, and health-system preparedness. Adaptation works best when it is local, well funded, updated with new data, and designed with the people most exposed to risk.
Why it matters
Climate change matters because it touches food, water, health, homes, energy, ecosystems, migration, infrastructure, insurance, finance, security, and justice. It is not only an environmental problem; it is a systems problem. Every increment of warming increases risks, and every avoided increment reduces future harm. The choices made this decade shape the climate conditions that people, cities, farms, coastlines, and ecosystems will face for generations.