Scientists have developed an understanding of the Earth’s climate system through years of observations, theory development, and model building. We know with high confidence that climate change is happening today and is the result of greenhouse gas emissions caused by human activity.
What is causing climate change?
Greenhouse gases, like carbon dioxide (CO2) and methane, trap heat in the Earth’s atmosphere. Human activities, especially burning fossil fuels, are causing our planet to warm. The concentration of CO2 in the air has reached more than 410 parts per million by volume (ppm), compared to about 280ppm in 1750 (around the start of the Industrial Revolution), increasing the amount of energy that is being trapped in the climate system and causing the surface temperature of the planet to rise. This warming is happening faster than natural changes in the past and is affecting our climate now. The rising global temperature will be increasingly prevalent and will lead to wider changes to our weather. Climate change is already affecting our world through:
- more frequent and severe heatwaves
- droughts, and storms
- rising sea levels threatening coastal communities
- changes in plant and animal habitats
- impacts on agriculture and food production
How is climate change measured?
Scientists have maintained a long-running observational record of the levels of carbon dioxide in the atmosphere since the late 1750s. Climate change is most commonly measured using the average surface temperature of the planet. Different estimates from the UK Met Office, NASA, NOAA and Berkeley Earth all show a rising trend in average global surface temperature over the last century despite using slightly different methodologies. Year-on-year, natural fluctuations can be seen on top of this long-term warming. For this reason, scientists traditionally use a period of at least 30 years to identify a genuine climate trend.
What are the impacts of climate change?
Climate change is impacting our world, with far-reaching consequences.
- Extreme weather events are becoming more common. Globally, we’re experiencing fewer cold days and nights but more warm ones. Many areas are seeing an increase in heavy rainfall, and regions like Europe, Asia, and Australia are facing longer and more frequent warm spells.
- Ice sheets and glaciers around the world, from Greenland to Antarctica, are shrinking contributing to sea level rise. This combined with permafrost warming has global implications for climate and sea levels.
- Excess heat trapped by greenhouse gases is absorbed by the oceans, leading to rising sea levels and increased acidity. This threatens marine ecosystems, particularly coral reefs.
Where can I learn more?
Impacts from climate change are already being felt today and will continue to increase in the future. Action to limit future global greenhouse gas emissions will help restrict future changes in the climate system. Read the latest evidence about how and why our global climate is changing from some of the world’s leading science organisations:
- The Intergovernmental Panel on Climate Change provides the most comprehensive summaries of the latest research on climate science and the impacts of climate change.
- The UK Royal Society and the US National Academy of Sciences are fellowships of the world’s most eminent scientists. Together they published a joint statement on the science of climate change.
- The Geological Society has published a document setting out the evidence for and risks of climate change from a geological perspective.
- The American Institute of Physics hosts a detailed history of global warming.
- The United Nations Environment Programme (UN Environment) is the leading global environmental authority that sets the global environmental agenda.
- NASA provides the public with accurate and timely news and information about Earth’s changing climate.
- The Met Office produces the UK Climate Projections. These are the most up-to-date assessment of how the climate of the UK may change over the 21st century.
- The UK Climate Risk website hosts all of the outputs for the Climate Change Risk Assessment Evidence Report, from technical chapters through to the research projects through to summaries of the advice.
