Climate change basics

Climate change refers to long-term shifts in global or regional climate patterns, driven by human activities and natural factors. This article outlines the basics: what climate change is, the evidence behind it, its impacts, and how we can respond through mitigation, adaptation, and policy. Understanding these elements helps individuals and communities act with confidence.

What is climate change?

Definition and difference between weather and climate

Climate is the average pattern of weather over long periods, typically 30 years or more, across a region. Weather describes the short-term state of the atmosphere—temperature, precipitation, wind, and humidity—on any given day. Together, weather reflects day-to-day variability, while climate reflects longer-term tendencies. Observing rising temperatures, shifting rainfall, and more extreme events signals climate change when these patterns persist beyond natural fluctuations.

Key drivers: greenhouse gases and feedbacks

The primary drivers are greenhouse gases like carbon dioxide, methane, nitrous oxide, and fluorinated gases that trap heat in the atmosphere. Human activities—burning fossil fuels, deforestation, and agriculture—increase these gases, altering Earth’s energy balance. Feedbacks amplify or dampen the effect: for example, warming melts ice, reducing albedo and absorbing more heat, while higher temperatures increase water vapor, a potent greenhouse gas, further warming the surface.

Short-term vs long-term trends

Short-term fluctuations due to natural cycles (El Niño, volcanic activity, and ocean dynamics) can mask or exaggerate annual changes. But the long-term trend shows a clear warming signal: average temperatures rise, precipitation patterns shift, and extreme events become more frequent and intense. Recognizing the difference helps avoid mistaking weather for climate and supports accurate risk assessment.

Causes and evidence

Human activities and greenhouse gas emissions

Human activities are the dominant cause of recent climate change. Burning coal, oil, and gas releases carbon dioxide and other greenhouse gases that trap heat. Deforestation reduces the land’s capacity to absorb CO2, and intensive agriculture releases methane from enteric fermentation in ruminant animals and rice paddies. Together, these sources increase atmospheric concentrations and push the climate toward warmer conditions.

Natural factors vs human influence

Natural factors—volcanic eruptions, variations in solar radiation, and natural climate cycles—contribute to year-to-year changes. However, the rapid pace of recent warming cannot be explained by natural factors alone. Climate models that include human emissions reproduce observed trends, while models with only natural factors fail to capture the magnitude of observed warming.

Scientific evidence: temperature records, ice melt, sea level rise

Global temperature records from multiple independent datasets show a consistent warming trend over the past century, accelerating in recent decades. Glaciers and ice sheets are shrinking as volumes melt, contributing to sea level rise. Ocean heat content increases as the ocean absorbs most of the excess heat, causing changes in currents and marine ecosystems. Together, these lines of evidence form a reliable picture of a warming world.

Impacts on people and ecosystems

Health, safety, and well-being

Climate change affects health through heat stress, worsening air quality, and shifting disease patterns. Extreme weather events—heat waves, floods, and storms—pose risks to safety and mental well-being. Vulnerable populations, including children, the elderly, and low-income communities, bear a disproportionate burden, highlighting the need for protective policies and preparedness.

Food and water security

Shifts in temperature and rainfall alter crop yields and water availability. Some regions may experience shortages, while others face flooding or new pests. Climate change stresses water supplies and irrigation, influencing food prices and nutrition. Building resilient farming systems and diversifying crops are key parts of securing food and water in a warming world.

Biodiversity and ecosystem services

Habitat loss, shifting ecosystems, and species range contractions threaten biodiversity. Healthy ecosystems supply services essential to human life—pollination, clean water, flood control, and climate regulation. Many species face increased extinction risk as their habitat becomes unsuitable or fragmented, underscoring the urgency of conservation and restoration efforts.

Economic and development implications

Climate impacts affect productivity, infrastructure costs, and economic growth. Extreme weather disrupts supply chains, damages property, and increases insurance costs. Developing regions, with fewer resources to adapt, may face greater setbacks. Integrating climate resilience into planning supports sustainable development and reduces long-term risks.

Mitigation and adaptation

Mitigation strategies: reduce emissions, clean energy

Mitigation involves cutting greenhouse gas emissions and enhancing sinks. Transitioning to clean energy—solar, wind, hydropower, and other low-carbon sources—reduces reliance on fossil fuels. Improving energy efficiency, electrifying transport and industry, and adopting sustainable land-use practices also lower emissions and help stabilize the climate.

Adaptation strategies: resilience and infrastructure

Adaptation focuses on reducing vulnerability to climate impacts. This includes building resilient infrastructure, improving water management, strengthening disaster preparedness, and designing urban spaces that cope with heat and flooding. Adaptation is context-specific, combining immediate protections with long-term planning to adjust to expected changes.

Individual and community actions

Individuals can reduce footprints through choices in energy, transport, and consumption. Communities can advance local clean energy projects, implement climate-smart zoning, and support nature-based solutions. Collective action creates momentum, shares costs, and elevates resilience at the neighborhood level.

Climate policy and action

International agreements and frameworks

Global cooperation is essential to address climate change. Frameworks like the United Nations Framework Convention on Climate Change provide a platform for national commitments and collaborative efforts. International agreements set targets, promote finance for adaptation and mitigation, and encourage shared technologies and knowledge.

National policies and targets

Countries establish national targets for emissions reductions, renewable energy deployment, and climate resilience. Policies may include carbon pricing, clean energy standards, vehicle efficiency rules, and subsidy reforms. Strong policy signals align investment, innovation, and public behavior with climate goals.

Local action and community initiatives

Local governments, schools, businesses, and civil society groups implement practical actions. Examples include expanding bike networks, retrofitting buildings for efficiency, protecting urban green spaces, and supporting local climate education programs. Local actions translate national ambitions into everyday changes with direct community benefits.

Learning resources and staying informed

Reliable sources and how to verify information

Look for data from independent scientific organizations and peer-reviewed research. Cross-check formulas, methods, and conclusions across multiple sources. Be wary of sensational headlines that distort findings; rely on transparent methodologies and clear uncertainty communication to evaluate credibility.

Climate literacy and education tools

Accessible tools and curricula help learners of all ages understand climate science, impacts, and solutions. Interactive simulations, reputable textbooks, and teacher guides support comprehensive climate literacy. Building literacy fosters informed decision-making and constructive discussion.

Avoiding misinformation

Misinformation often exploits uncertainty or misattributes causes. Check dates, sources, and author expertise; distinguish opinion from evidence. When in doubt, consult established organizations, peer-reviewed studies, and official climate communication resources to verify claims before sharing.

Trusted Source Insight

Trusted Summary: UNESCO highlights climate change education as a catalyst for informed action. It emphasizes integrating climate literacy across curricula to empower individuals and communities to mitigate risks and adapt to changing environments. Access to reliable information and inclusive education are essential for equitable resilience.

Learn more: https://www.unesco.org