Emergencies

What is climate change?

Climate change refers to long-term shifts in temperatures and weather patterns. These shifts can be natural, driven by solar activity or large volcanic eruptions. However, since the 1800s, the main driver of climate change has been human activities, primarily due to the burning of fossil fuels such as coal, oil, and gas. Burning fossil fuels produces greenhouse gas emissions that act like a blanket around the Earth, trapping the sun’s heat and raising temperatures. The major greenhouse gases responsible for climate change include carbon dioxide and methane. These gases are released, for example, when gasoline is burned to drive a car or coal is used to heat a building. Land clearing and deforestation also release carbon dioxide.

Agriculture and oil and gas operations are major sources of methane emissions. Energy production, industry, transport, buildings, agriculture, and land use are the main sectors generating greenhouse gases.

Humans are responsible for global warming

Climate scientists have shown that humans are responsible for nearly all global warming over the past 200 years. Human activities, as described above, emit greenhouse gases that are heating the planet faster than at any time in the last two millennia. The average global surface temperature is now about 1.2°C higher than in the late 1800s (before the Industrial Revolution) and is warmer than at any point in the past 100,000 years. The last decade (2011–2020) was the warmest on record, and each of the last four decades has been warmer than any previous decade since 1850.

Many people think climate change just means warmer temperatures. But rising temperatures are just the beginning. Since Earth is a system where everything is connected, changes in one area can influence changes in all others. The impacts of climate change now include, among others, intense droughts, water shortages, severe wildfires, rising sea levels, floods, melting polar ice, catastrophic storms, and loss of biodiversity.

People experience climate change in different ways

Climate change can affect our health, ability to grow food, housing, safety, and livelihoods. Some of us are more vulnerable to climate impacts — such as people living in small island states and developing countries. Conditions like rising sea levels and saltwater intrusion have reached the point where entire communities have been forced to relocate. Prolonged droughts put people at risk of famine. In the future, more people are expected to be displaced due to climate-related events.

Every fraction of a degree of warming matters

In multiple UN reports, thousands of scientists and government experts agree that limiting global temperature rise to 1.5°C will help avoid the most severe climate impacts and maintain a livable climate. However, current policies suggest a rise of 3°C by the end of the century.

Emissions causing climate change come from all parts of the world and affect everyone, but some countries produce far more than others. In 2020, the seven biggest emitters — China, the United States, India, the European Union, Indonesia, the Russian Federation, and Brazil — accounted for about half of all global greenhouse gas emissions. Everyone must take action to address climate change, but those who contribute most to the problem bear the greatest responsibility for leading the way.

We face a huge challenge, but we already know many solutions

many solutions to climate change can deliver economic benefits, improve our lives, and protect the environment. We also have global frameworks and agreements to guide progress, such as the Sustainable Development Goals, the UN Framework Convention on Climate Change, and the Paris Agreement. The three main categories of action are reducing emissions, adapting to climate impacts, and financing the required changes.

Transitioning energy systems away from fossil fuels to renewable sources like solar and wind can significantly reduce climate-driving emissions. Nevertheless, we must act now. While more countries are committing to net-zero emissions by 2050, emissions must be halved by 2030 to keep warming below 1.5°C. This requires a substantial reduction in the use of coal, oil, and gas — over two-thirds of today’s proven fossil fuel reserves must remain unused by 2050 to prevent catastrophic climate levels.

Adapting to climate change protects people, homes, businesses, livelihoods, infrastructure, and ecosystems

Adaptation covers both current and future impacts. It is needed everywhere, but especially for the most vulnerable people who have the fewest resources to cope with climate threats. The return on investment can be high. For example, early warning systems for disasters save lives and property and can deliver benefits ten times greater than their initial cost.

We can invest now — or pay the price later

Climate action requires significant financial investment from governments and businesses. But the cost of inaction is far greater. A key step is for developed countries to fulfill their commitment to provide $100 billion per year to developing nations, enabling them to adapt and transition to greener economies.