Climate science

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Weather is what happens day to day: rain, wind and sun. The regular pattern of weather over many years is the climate.

Weather is what happens day to day (rain, wind, sun). The regular pattern of weather over many years is the climate[1].

The Earth can look huge from space, but what makes life possible is fragile: the thin layer of air, water, and ice we call our atmosphere. When we change the atmosphere, we change the rules for everything that depends on it.

What is climate change?

A long-term shift

Climate change means a long-term shift in global temperatures and weather patterns[1]. Global warming is one part of climate change: the increase in Earth’s average temperature.

The climate can change naturally due to changes in the solar cycle or large volcanic eruptions. But what worries scientists today is the speed and the cause of the change[2], [3]. Global temperature has increased faster since 1970 than in any other 50-year period in the past 2000 years[4], [5].

How has the climate changed?

We can measure climate change directly

Measurements collected over many years show clear changes in temperature, carbon dioxide and sea level.

10 years

The warmest on record

The past ten years are the ten warmest years on record[6].

422 ppm

Carbon dioxide in 2024

The atmosphere now contains far more carbon dioxide than before the Industrial Revolution: about 422 ppm in 2024 compared to about 280 ppm in the 1800s[7], [8].

20-25 cm

Global sea-level rise

Global mean sea level increased by about 20-25 cm since 1900[9], [4].

Graph comparing atmospheric carbon dioxide and global temperature from 1850 to 2024
Carbon dioxide vs global temperature (1850-2024). NOAA Climate.gov graphic based on NOAA data [10].
What causes climate change today?

Greenhouse gas emissions from human activity

Today’s long-term warming is mainly caused by greenhouse gas emissions from human activity[4], [2].

79%

In 2023, carbon dioxide made up about 79% of UK greenhouse gas emissions by warming effect, and methane about 15%[11].

15%
01

Burning fossil fuels

Burning fossil fuels (coal, oil, gas) for electricity, heating and transport releases greenhouse gases as byproducts of combustion.

02

Cutting down forests

Cutting down forests for timber and changing land use removes nature’s way of taking carbon dioxide out of the air and creates more carbon dioxide in the process.

03

Farming animals

Farming of animals for meat leads to release of methane from their digestion and manure.

How do greenhouse gases warm the planet?

A blanket around the Earth

Greenhouse gases act like a blanket around the Earth. After the Sun warms Earth’s surface, the surface gives off energy as infrared radiation (heat). Greenhouse gases absorb some of this infrared radiation and then re-emit it in all directions, including back towards the surface, slowing heat escape into space[12].

It is good that we have some greenhouse gases in our atmosphere: they keep the planet warm enough for life. However, as human activities add more greenhouse gases, the greenhouse effect becomes stronger, so the planet’s average temperature increases[4], [12].

Diagram of solar energy entering the atmosphere and heat being retained by greenhouse gases
Greenhouse effect diagram. Image from the Royal Society, based on a figure from the US EPA [13].
How does climate change lead to extreme events?

The Earth is a deeply interconnected system

The effects of warming are felt everywhere: a warmer world makes extreme weather more likely and more severe[4].

Warmer air can hold more water vapour (about 7% more per 1 °C), which means storms can drop more rain in a short time[14]. Enormous rainfall in Pakistan in 2022 affected about 33 million people, with nearly 8 million displaced and more than 1,700 deaths[15], [16].

Warming increases evaporation, so land can dry out faster making heatwaves and droughts more intense[14]. In 2022, the UK reached 40.3 °C for the first time on record[18]. Across Europe that summer, researchers estimated about 61,672 heat-related deaths[19].

Aerial view of a flooded residential area in Pakistan in 2022
Pakistan floods (2022). Aerial view of a flooded residential area in Dera Allah Yar, Jaffarabad district, Balochistan province, Pakistan, 30 August 2022. Photo: Fida Hussain / AFP via Getty Images [17].
Tipping points

Our oceans are warming too, which combined with melting ice sheets, could hugely shift ocean circulation and the global weather systems that depend on it. These severe, long-term, global changes are called “tipping points”. We have not experienced a tipping point in human history, but many years ago, slower ocean circulations led to drastic cooling in Europe and global rainfall shifts that would be catastrophic for food production today. The greater the warming we cause, the more likely crossing tipping points becomes.

What are scientists doing?

Measuring a changing planet

New technologies help researchers observe the oceans and ice sheets and give earlier warning of future tipping points.

The Advanced Research + Invention Agency exists to fund frontier science that could benefit everyone. Their Scoping Our Planet opportunity space is a collective effort that supports scientists and engineers who use new technologies to: measure how the Earth is changing, help us to understand why it is changing, and provide the information that we all need to survive in a rapidly changing world. Through Launch 4 Change, university students develop and launch climate science payloads to explore new ways to measure our planet. They also mentor school pupils through UKROC, the youth rocketry competition. Our research teams are doing the same: creating new robots and computer models to assess how the oceans and ice sheets are changing and help to provide early warning of any future tipping point.

Autonomous robot at sea
Autonomous robot monitoring the temperature of the ocean. Credit: Oshen.
Drone flying above a melting glacier in Greenland
Drone surveying the melting glaciers in Greenland. Credit: Marble.
Scientific visualisation of global ocean currents
Modelling ocean currents and how they change in a warming climate. NASA Scientific Visualization Studio, Perpetual Ocean 2: Western Boundary Currents, based on the ECCO ocean circulation model [20].

With a better understanding of the expected impacts of climate change, we can plan for the future. Governments can take a wide range of actions to adapt for future changes, from installing better flood defences, to securing future food production, to urban planning for cooler cities.

What can you do?

We are not powerless

Every individual can help reduce the effects of climate change and build towards a more sustainable future. To cut emissions, we can all choose to change daily habits of food consumption, minimise waste, and prioritise electric transport options and renewable energy[4], [21]. Together, we can build a better future.

References and image credits21 sources
  1. Royal Geographical Society (with IBG). Changing climates (KS3 resource). Educational resource, 2024. Accessed 24 February 2026.
  2. Intergovernmental Panel on Climate Change (IPCC). Climate Change 2021: The Physical Science Basis - Summary for Policymakers, 2021. Accessed 24 February 2026.
  3. UN News. IPCC report: “Code red” for human driven global heating, warns UN chief. UN News story, 2021. Accessed 24 February 2026.
  4. Intergovernmental Panel on Climate Change (IPCC). Climate Change 2023: Synthesis Report - Summary for Policymakers, 2023. Accessed 24 February 2026.
  5. United Nations. Climate change: Key findings. UN Climate Change explainer page, 2024. Accessed 24 February 2026.
  6. World Meteorological Organization. WMO confirms 2024 as warmest year on record at about 1.55 °C above pre-industrial level. Press release, 10 January 2025. Accessed 24 February 2026.
  7. NOAA Climate.gov. Climate change: atmospheric carbon dioxide (global average CO2 record in 2024). Understanding Climate feature, 2025. Accessed 24 February 2026.
  8. Copernicus Climate Change Service (C3S). Copernicus: 2024 is the first year to exceed 1.5 °C above pre-industrial level. Press release, 10 January 2025. Accessed 24 February 2026.
  9. European Environment Agency. Global and European sea level rise. Indicator page, published 26 November 2025. Accessed 24 February 2026.
  10. NOAA Climate.gov. Carbon dioxide vs global temperature anomaly, 1850-2024, 2025. NOAA Climate.gov media asset, published 29 May 2025.
  11. Department for Energy Security and Net Zero (DESNZ). 2023 UK greenhouse gas emissions, final figures. Statistical release, 2025. Accessed 24 February 2026.
  12. Met Office. Causes of climate change (greenhouse effect and greenhouse gases). Met Office explainer page, 2024. Accessed 24 February 2026.
  13. The Royal Society. The basics of climate change, 2025. Greenhouse effect figure on page; image based on a figure from the US EPA. Accessed 16 March 2026.
  14. Intergovernmental Panel on Climate Change (IPCC). Climate Change 2021: The Physical Science Basis (AR6 WG1) - Chapter 8: Water Cycle Changes, 2021. Accessed 24 February 2026.
  15. World Bank. Pakistan Floods 2022: Post-Disaster Needs Assessment. Report, 2022. Accessed 24 February 2026.
  16. British Red Cross. Climate change and Pakistan flooding: affecting millions. British Red Cross story page, 2022. Accessed 24 February 2026.
  17. Fida Hussain. Flooded residential area in Dera Allah Yar, Jaffarabad district, Balochistan province, Pakistan, 2022. AFP via Getty Images, 30 August 2022.
  18. Met Office. A milestone in UK climate history (40.3 °C on 19 July 2022). Met Office news article, 2022. Accessed 24 February 2026.
  19. J. Ballester et al. Heat-related mortality in Europe during the summer of 2022. Nature Medicine, 2023. Accessed 24 February 2026.
  20. NASA Scientific Visualization Studio. Perpetual Ocean 2: Western Boundary Currents, 2025. Visualization based on the ECCO ocean circulation model.
  21. United Nations. ActNow: Ten actions to combat climate change. UN ActNow page, 2024. Accessed 24 February 2026.