Weather is what the atmosphere is doing over short periods, such as today’s temperature, a thunderstorm this afternoon, or a snowy week. It can change quickly because winds, clouds, and air masses are always moving. Climate describes the usual pattern of weather in a place over many years, including typical seasons and the range of expected conditions. A single cold day does not disprove global warming, just as one hot day does not prove it. Scientists study climate by examining long-term records, often using 30-year averages, to identify trends that rise above normal year-to-year variation. Climate change means those long-term patterns are shifting, affecting temperatures, rainfall, and extremes.

Many independent observations show that Earth is warming. Thermometers on land and sea show a long-term rise in global average surface temperature. Oceans are absorbing most of the extra heat, so measurements also reveal increasing ocean heat content. Glaciers and ice sheets are losing ice, Arctic sea ice has declined, and global sea level has risen as seawater expands when warmed and land ice melts. Spring events, such as flowering and animal migration, are occurring earlier in many places. No one piece of evidence stands alone: scientists compare direct measurements, satellite observations, ice cores, and natural records. Together, these lines of evidence show a broad, persistent warming trend rather than a local or temporary change.

The greenhouse effect is a natural process that keeps Earth warm enough for life. Sunlight passes through the atmosphere and warms Earth’s surface. The surface then releases energy upward as infrared radiation. Greenhouse gases, including water vapor, carbon dioxide, methane, and nitrous oxide, absorb and re-release some of this outgoing energy, slowing its escape to space. Adding more long-lived greenhouse gases strengthens this effect and raises Earth’s energy balance, causing the planet to warm until it can again release as much energy as it receives. The effect is not a glass roof trapping heat; it is an atmospheric process involving radiation. Without the natural greenhouse effect, Earth would be far colder, but increased gases are changing the climate.

Human activities are the main cause of recent global warming because they add large amounts of greenhouse gases to the atmosphere. Burning coal, oil, and natural gas for electricity, transportation, heating, and industry releases carbon dioxide that was stored underground for millions of years. Cutting forests can add carbon dioxide and removes trees that would otherwise absorb some of it. Agriculture produces methane from livestock and rice fields and nitrous oxide from soils and fertilizers. Cement production and waste also contribute emissions. These sources have distinct chemical fingerprints and match the observed rise in atmospheric carbon dioxide. Reducing emissions through cleaner energy, efficiency, electrification, and protecting forests can limit future warming and related risks.

Earth’s climate has always changed because of natural influences, but these factors do not explain the rapid warming observed today. Volcanic eruptions can cool the planet temporarily when particles high in the atmosphere reflect sunlight. Changes in the Sun’s energy output can affect climate slightly, while slow changes in Earth’s orbit help drive ice-age cycles over thousands of years. Ocean patterns such as El Niño and La Niña shift heat and rainfall from year to year, creating warmer or cooler periods in different regions. Scientists include these influences in climate studies and models. Their effects do not match the long-term warming pattern, whereas rising greenhouse gases do. Natural variability still shapes weather, but it occurs on top of a human-warmed climate.

A warmer atmosphere adds energy to weather systems and holds more water vapor, which can increase the chance of intense heat waves and heavy rainfall. Climate change does not create every storm, drought, or wildfire, but it can make certain events more likely or more severe. Oceans absorb much of the added heat, and seawater expands as it warms. Melting land ice from glaciers and ice sheets also raises sea level. Higher seas increase coastal flooding during high tides and storms, threatening homes, roads, wetlands, and freshwater supplies. The impacts are often greatest for communities with fewer resources to prepare, evacuate, and rebuild.

Plants, animals, and microorganisms depend on suitable temperatures, water, food, and habitats. As climate conditions shift, many species must move, change seasonal behaviors, adapt, or face population declines. Earlier spring warming can disrupt relationships such as flowers blooming before pollinators are active or birds arriving after peak insect seasons. Marine ecosystems are also affected: warmer oceans can stress coral reefs, while absorbed carbon dioxide makes seawater more acidic. Healthy ecosystems help people by storing carbon, filtering water, reducing flood risks, and supporting food webs. Protecting connected habitats and reducing other pressures, such as pollution and habitat loss, gives species a better chance to respond.

Climate change can affect health directly through dangerous heat, smoke from wildfires, flooding, and stronger storms. It can also affect health indirectly when crops fail, water becomes scarce or contaminated, or disease-carrying insects expand into new areas. Heat is especially risky for older adults, young children, outdoor workers, and people with some medical conditions, although anyone can be affected. Farmers may face changing growing seasons, drought, floods, and new pests, which can raise food prices or reduce harvests. Water systems can be strained by dry periods and damaged by floods. Planning for cooling, clean water, emergency alerts, and resilient farms can reduce these risks.

Mitigation means limiting future warming by reducing greenhouse gas emissions and protecting natural systems that absorb carbon dioxide. The largest opportunities include using less energy, improving efficiency, replacing fossil fuels with low-carbon electricity, expanding public transit and electric vehicles, and reducing methane leaks. Homes, schools, businesses, and governments all have roles because energy choices are shaped by buildings, transportation networks, laws, and available technology. Forests, wetlands, grasslands, and healthy soils can store carbon, but they cannot replace rapid cuts in fossil fuel emissions. Effective mitigation also considers fairness by making clean energy, reliable transportation, and good jobs accessible to more people.

Adaptation means preparing for climate impacts that are already occurring or cannot be completely avoided. Communities can plant shade trees, improve drainage, update building codes, create cooling centers, protect wetlands, and strengthen emergency plans. Good adaptation is local: a coastal town may plan for flooding, while an inland community may focus on heat, wildfire smoke, or drought. Students can contribute by learning about local risks, sharing trustworthy information, conserving energy and water, and joining projects such as tree planting or school waste audits. Student voices also matter in school boards and local meetings. The strongest actions combine practical preparation with mitigation, because adapting becomes harder as warming increases.