SafekipediaClimate change
Adapted from Wikipedia · Discoverer experience
Earth's average temperature has risen by nearly 1.5 °C since the Industrial Revolution, mainly because of human activities like burning fossil fuels such as coal, oil, and natural gas. These activities release greenhouse gases, especially carbon dioxide, which trap heat in the atmosphere. This process, known as global warming, is causing significant changes to our planet’s climate system.
Climate change affects the environment in many ways. We see expanding deserts, more frequent heat waves, intensified wildfires, melting glaciers, shrinking sea ice, and rising sea levels. These changes also impact wildlife, with many species needing to move to new areas or facing extinction. Even if we take steps to reduce warming, some effects will last for centuries, including changes to the oceans and continued sea level rise.
People around the world face growing risks from climate change, such as flooding, extreme heat, and shortages of food and water. It can also lead to health problems, economic losses, and even conflicts. Poor communities, who contribute the least to greenhouse gas emissions, are often the most vulnerable. The World Health Organization considers climate change one of the greatest threats to global health this century.
In response, many countries have committed to the Paris Agreement, aiming to keep warming well below 2 °C. Efforts to address climate change include moving away from fossil fuels toward cleaner energy sources like wind, solar, hydro, and nuclear power. Protecting and expanding forests and using farming methods that store carbon in soil are also important strategies to help reduce greenhouse gases in the atmosphere.
Terminology
Before the 1980s, scientists weren't sure whether greenhouse gases or air pollution had a bigger impact on Earth's temperature. They used the term inadvertent climate modification to describe human effects on the climate. Later, the terms global warming and climate change became common. Global warming means the rise in Earth's average temperature, while climate change includes this warming and its effects on weather patterns like precipitation.
Today, climate change is the more widely used term. Some people also use words like climate crisis or climate emergency to show how serious the situation is.
Global temperature rise
Further information: Global surface temperature
Main articles: Climate variability and change; Temperature record of the last 2,000 years; and Paleoclimatology
Over the past few million years, Earth's climate has gone through big changes, like ice ages and warmer periods. About 125,000 years ago, during a warm time called the Last Interglacial, temperatures were a bit warmer than today, and sea levels were much higher. Around 20,000 years ago, during a cold period called the last glacial maximum, it was much colder, and sea levels were lower.
Since the Industrial Revolution began around 1850, human activities—especially burning fossil fuels—have added greenhouse gases to the atmosphere. These gases trap heat and cause the planet to warm up. Since 1970, the buildup of these gases has led to a clear rise in global temperatures. We are now seeing changes like glaciers melting, plants blooming earlier, and more heavy rain. Different parts of the world are warming at different speeds. For example, the Arctic is warming much faster than other areas because melting ice absorbs more heat. Scientists predict that global temperatures will continue to rise, depending on how much we reduce our emissions in the future.
Causes of recent global temperature rise
Main article: Causes of climate change
The Earth's climate naturally changes over time, but recent warming is mainly caused by human activities. One big factor is the increase of greenhouse gases in the atmosphere. These gases, like carbon dioxide (CO2), trap heat from the sun and keep it close to Earth, making our planet warmer. Since the Industrial Revolution, burning fossil fuels such as coal, oil, and natural gas has released huge amounts of these gases.
Greenhouse gases let sunlight reach Earth, but they trap the heat that the Earth radiates back into space. This is called the greenhouse effect. While some gases like water vapor change with temperature, others like CO2 are added to the atmosphere by human actions. Since 1750, levels of CO2 have risen by about 50%, and methane, another greenhouse gas, has risen by 164%. These increases come mainly from burning fossil fuels, cutting down forests, and farming practices. These gases stay in the atmosphere for a long time, continuing to warm the planet.
Modelling
A climate model is a tool that helps us understand how the Earth's climate works. It looks at natural changes, like shifts in the Earth's path around the Sun or volcanic eruptions, and how they affect the weather. Scientists use these models to guess how much the Earth will warm up in the future based on things we do, like burning fossil fuels.
These models are checked to see if they can correctly show the climate we already know. Sometimes, older models did not predict things like shrinking Arctic ice very well, but newer models are getting better. Some models also look at how human choices, like how much energy we use, will change the climate in the future. These models help us see possible outcomes depending on the choices we make.
Impacts
Main article: Effects of climate change
The environmental effects of climate change are wide-ranging, affecting oceans, ice, and weather patterns. Since the 1950s, we have seen more frequent droughts, heat waves, and extreme weather events. Global sea levels are rising due to melting ice and warming oceans, and this rise is expected to continue throughout the 21st century. The Arctic sea ice is shrinking, and oceans are becoming more acidic as they absorb carbon dioxide from the atmosphere.
Climate change also impacts nature and wildlife. Many species are moving to cooler areas, and some are struggling to survive. In the oceans, creatures like corals and shellfish find it harder to build their homes, and harmful algae blooms are becoming more common. Humans are affected too, with health risks increasing due to extreme heat and changes in disease patterns. Food supplies can be threatened by changes in weather and water availability, and some people may be forced to move if their homes become uninhabitable.
Ecological collapse. Coral bleaching from thermal stress has damaged the Great Barrier Reef and threatens coral reefs worldwide. Extreme weather. Drought and high temperatures worsened the 2020 bushfires in Australia. Habitat destruction. Many arctic animals rely on sea ice, which has been disappearing in a warming Arctic. Pest propagation. Mild winters allow more pine beetles to survive to kill large swaths of forest. |
Environmental migration. Sparser rainfall leads to desertification that harms agriculture and can displace populations. Shown: Telly, Mali (2008). Agricultural changes. Droughts, rising temperatures, and extreme weather negatively impact agriculture. Shown: Texas, US (2013). Tidal flooding. Sea-level rise increases flooding in low-lying coastal regions. Shown: Venice, Italy (2004). Storm intensification. Bangladesh after Cyclone Sidr (2007) is an example of catastrophic flooding from increased rainfall. Heat wave intensification. Events like the 2022 Southern Cone heat wave are becoming more common. |
Reducing and recapturing emissions
Climate change can be slowed by cutting down on greenhouse gases and finding ways to take carbon dioxide out of the air. To keep global temperatures from rising too much, the world needs to reach “net-zero” emissions by 2070. This means big changes in how we use energy, where we live, and how we travel.
Renewable energy sources like solar and wind power are very important. Many countries are working hard to use less coal and oil. By 2050, most electricity could come from clean energy sources. We can also reduce energy use by making buildings and machines more efficient. Farming and industry can help too by using methods that produce less pollution and by protecting forests, which naturally absorb carbon dioxide.
Other ideas, like taking carbon out of the air directly, are being studied but come with risks. For example, some scientists suggest reflecting a tiny bit of sunlight away from Earth to cool it down, but this idea has risks and isn’t a replacement for cutting emissions. The best path forward is to use clean energy and protect natural areas that help keep our planet healthy.
Adaptation
Adaptation is the way people and nature adjust to changes in climate. This can include moving away from areas that might flood, building structures to stop water, and changing farming methods to grow crops in new conditions. Not all places have the same ability to adapt, and some countries, especially those with fewer resources, find it harder.
Nature also adapts to climate change. For example, animals and plants can move to areas where the climate is more comfortable. Humans can help by protecting natural areas and connecting habitats so species can move more easily. These actions not only help nature but also protect people by reducing risks like flooding and extreme heat.
Policies and politics
See also: Politics of climate change and Climate change mitigation § Policies
Countries that are most vulnerable to climate change have usually contributed little to global emissions. This creates questions about fairness. Tackling climate change helps achieve the UN's Sustainable Development Goals, like ending poverty and reducing inequality. Sustainable Development Goal 13 calls for urgent action on climate change.
The geopolitics of climate change is complicated. It is sometimes seen as a free-rider problem, where all countries benefit from others' efforts to cut emissions, but may lose out by switching to a low-carbon economy themselves. However, ending fossil fuel subsidies can greatly cut emissions and save lives by reducing air pollution. Money saved could support a transition to clean energy.
Policy options
Further information: Climate policy
Many policies aim to cut emissions. Carbon pricing covers about 20% of global emissions. This includes carbon taxes and emissions trading systems. Ending fossil fuel subsidies could cut global emissions by 28%. Saved money could fund clean energy. Other methods include efficiency standards for vehicles and rules for industries. Some countries require more renewable energy in power production.
Climate justice
Policy through climate justice aims to address inequality. Wealthier nations, responsible for most emissions, should help poorer countries adapt. For example, the wealthiest 10% of people caused 50% of emissions in 2023, while the bottom 50% caused just 8%.
International climate agreements
Further information: United Nations Framework Convention on Climate Change
Almost all countries are part of the 1994 United Nations Framework Convention on Climate Change (UNFCCC), aiming to prevent dangerous human effects on the climate. The 1997 Kyoto Protocol set binding emission limits for developed countries. The 2015 Paris Agreement aims to keep warming below 2.0 °C, with a goal of 1.5 °C. Countries must regularly set tougher goals. The 1987 Montreal Protocol helped by banning ozone-depleting gases, which are also powerful greenhouse gases.
National responses
In 2019, the United Kingdom parliament declared a climate emergency, followed by others. The European Commission aims for carbon neutrality by 2050, with all new cars in Europe to be zero-emission vehicles from 2035. Countries like South Korea, Japan, and China aim for carbon neutrality by 2050 or 2060. However, many nations still plan to use coal. Current plans suggest only small emission cuts compared to what is needed to limit warming.
Society and culture
Public debate about climate change has been affected by denial and misinformation, which began in the United States and spread to other countries. These efforts often come from fossil fuel companies and groups that try to create doubt about scientific findings. This can make people unsure about whether climate change is real or serious.
Climate change became a big topic worldwide in the late 1980s. Movies and documentaries helped many people learn about it. Different groups of people think about climate change in various ways. For example, younger people and those with more education often worry more about it. Over time, more people have become concerned, with many saying that strong action is needed to address climate change.
People have held many protests to call for action on climate change. These include students skipping school on Fridays to demand better policies, and groups disrupting traffic to get attention. Lawsuits are also being used to push governments and companies to take stronger action on reducing harmful emissions. In 2025, an international court said that countries must work to stop climate change, and if they don’t, other countries can take legal action.
History
For broader coverage of this topic, see History of climate change science.
In the 1800s, scientists like Alexander von Humboldt and Joseph Fourier started to understand how Earth's climate works. They discovered that gases in the air, such as water vapor and carbon dioxide (CO2), trap heat and warm the planet. This is called the greenhouse effect.
Later, scientists like Svante Arrhenius and Guy Stewart Callendar showed that human activities, especially burning fossil fuels, increase CO2 levels and warm the Earth. By the late 20th century, most scientists agreed that humans were causing climate change. Today, scientists study how climate change affects specific weather events, helping us understand its real-world impacts.
Images
This article is a child-friendly adaptation of the Wikipedia article on Climate change, available under CC BY-SA 4.0.
Images from Wikimedia Commons. Tap any image to view credits and license.