What is climate change?

Through decades of observation, research, and model development, scientists have gained a deep understanding of the Earth’s climate system. There is now overwhelming evidence that climate change is occurring, primarily due to greenhouse gas emissions from human activities.

What is driving climate change?

Greenhouse gases, such as carbon dioxide (CO2) and methane, trap heat within the Earth’s atmosphere. Human activities, particularly the burning of fossil fuels, are responsible for this warming. The concentration of CO2 in the atmosphere has risen to over 410 parts per million (ppm), compared to around 280ppm in 1750 at the dawn of the Industrial Revolution. This increase in greenhouse gases amplifies the amount of heat being retained, causing the planet’s surface temperature to rise. This warming is occurring at an unprecedented rate, outpacing natural changes from the past, and is already having noticeable impacts on the climate. Some of the effects include:

• More frequent and intense heatwaves
• Increased droughts and storms
• Rising sea levels that threaten coastal communities
• Shifts in plant and animal habitats
• Disruptions to agriculture and food production

How is climate change measured?

Scientists have tracked atmospheric CO2 levels since the late 1700s, creating a long-standing record. Climate change is most commonly assessed by monitoring global surface temperatures. Various agencies, including the UK Met Office, NASA, NOAA, and Berkeley Earth, all report an upward trend in global temperatures over the last century, despite slight variations in methods. Because natural fluctuations occur year-to-year, scientists typically rely on at least 30 years of data to confirm a climate trend.

What are the consequences of climate change?

Climate change is already impacting our world with wide-reaching effects:

• Extreme weather events are becoming more frequent. Globally, there are fewer cold days and nights, and more warm ones. Many regions are experiencing heavier rainfall, while areas like Europe, Asia, and Australia are enduring longer, more frequent heatwaves.
• Ice sheets and glaciers worldwide, from Greenland to Antarctica, are melting, contributing to rising sea levels. This, combined with warming permafrost, has significant global implications for both the climate and sea levels.
• The excess heat trapped by greenhouse gases is being absorbed by the oceans, leading to rising sea levels and increasing acidity. This poses a serious threat to marine ecosystems, particularly coral reefs.

Where can I learn more?

The impacts of climate change are already visible and will continue to escalate in the future. Reducing global greenhouse gas emissions will be crucial in limiting further changes to the climate. To stay informed on the latest research and findings, consider consulting the following leading scientific organizations:

• The Intergovernmental Panel on Climate Change (IPCC), which offers comprehensive reports on climate science and its impacts.
• The UK Royal Society and the US National Academy of Sciences, which have released joint statements from some of the world’s top scientists on climate change science.
• The Geological Society, which provides evidence and insights on climate change from a geological standpoint.
• The American Institute of Physics, which details the history of global warming.
• The United Nations Environment Programme (UNEP), which sets the global environmental agenda.
• NASA, which shares up-to-date news and information on Earth’s changing climate.
• The UK Met Office, which offers the latest projections on how the UK’s climate might change throughout the 21st century.
• The UK Climate Risk website, which hosts detailed reports and research outputs on the Climate Change Risk Assessment.