Summary
Human activities are unequivocally the cause of observed warming, according to the IPCC. The WMO reports that 2024 was the first calendar year above 1.5°C (about 1.55°C), that 2025 was the second or third warmest year at 1.44°C, and that 2015 to 2025 were the 11 warmest years on record. The remaining 1.5°C carbon budget was estimated at about 130 GtCO2 from the start of 2025, roughly three years of current emissions. Policy is moving in different directions: the EU adopted a binding 90% net reduction target for 2040 in March 2026, while the US withdrawal from the Paris Agreement took effect on January 27, 2026. This guide gives the key facts and the solutions that matter most.
Climate change is one of the defining environmental challenges of this century. The Intergovernmental Panel on Climate Change (IPCC) states that it is unequivocal that human influence has warmed the atmosphere, ocean and land. For up-to-date data, see the NASA climate portal, the NOAA climate division and the WMO. For a longer treatment of the science, read our post on 10 climate change facts everyone should know.
What are the key climate change facts?
- The WMO put 2024 at about 1.55°C above the pre-industrial average, the first calendar year above 1.5°C, and 2025 at 1.44°C. Human-induced long-term warming is lower, at roughly 1.3 to 1.4°C, because the Paris limit refers to a long-term average.
- Atmospheric CO2 reached 423.9 ppm in 2024, the highest in at least 2 million years, according to the WMO.
- Global sea level has risen about 20 cm since 1900, and the WMO reports that the rate of rise doubled between 2016 and 2025 compared with the 1990s, reaching about 4.1 mm a year.
- The ocean absorbs more than 90% of the excess heat, and ocean acidity has risen by about 26% since pre-industrial times.
- Glaciers, polar ice sheets and Northern Hemisphere snow cover are shrinking, and glaciers lost mass for the third year in a row in 2025, according to the WMO.
- Heatwaves, heavy rainfall and droughts have become more frequent or intense, and attribution studies link many individual events to climate change.
- WWF’s Living Planet Report 2024 found that monitored wildlife populations fell by an average of 73% between 1970 and 2020, with climate change one of several pressures.
- Tropical forests continue to suffer from deforestation and land-use change, which release carbon and remove a major sink.
Read: Climate Change and Sustainable Development | Effects of Climate Change on Human Health
What climate change solutions can you act on?
Both personal and systemic ones. The IPCC finds that limiting warming to 1.5°C needs rapid, deep emissions cuts in all sectors, and that demand-side measures in end-use sectors such as transport, buildings and food can cut emissions by roughly 40 to 70% in those sectors by 2050. This does not mean that individuals alone can deliver 40 to 70% of all reductions, so policy and corporate action are essential.
- Use public transport, cycle or walk instead of driving for every journey, and cut flights.
- Switch to an electric or hybrid vehicle when you replace a car.
- Choose renewable electricity, and support renewable energy projects and policy.
- Use efficient appliances and LED lighting, and insulate your home.
- Eat less beef and lamb, and waste less food.
- Wash clothes at lower temperatures, and buy durable garments instead of fast fashion.
- Grow some food at home where you can, and support local tree planting and habitat projects.
- Support climate legislation and ask where your bank and pension invest.
Further resources: IPCC Sixth Assessment Report | UNFCCC | Sustainable Development Goals
Frequently Asked Questions About Climate Change
What is climate change and what causes it?
Climate change is a long-term shift in global temperatures and weather patterns. Some climate change is natural, but since the mid-20th century human activities have been the main driver, primarily the burning of coal, oil and gas, which releases CO2 and other greenhouse gases that trap heat. The IPCC’s Sixth Assessment Report states that human influence on warming is unequivocal.
How much has the Earth warmed so far?
The IPCC estimated about 1.1°C of human-caused warming in 2011 to 2020. The WMO reports that 2024 averaged about 1.55°C above 1850 to 1900, 2025 about 1.44°C, and the 2023 to 2025 average about 1.48°C. A single year above 1.5°C does not formally breach the Paris limit, which refers to a long-term average, but the margin is almost gone.
What are the main effects of climate change?
They include rising sea levels, more frequent and intense heatwaves, droughts and floods, melting glaciers and ice sheets, ocean acidification, shifting species ranges and biodiversity loss, disruption of agriculture and food security, more intense storms and wildfires, and serious health impacts such as the spread of vector-borne disease.
What is the Paris Agreement and what does it aim to achieve?
The Paris Agreement is an international treaty adopted in 2015 under the UN Framework Convention on Climate Change (UNFCCC). It aims to limit warming to well below 2°C and to pursue efforts to keep it to 1.5°C, through nationally determined contributions (NDCs), and to align finance flows with low-emission development. Nearly every country is a party, but the United States’ withdrawal took effect on January 27, 2026.
Can individuals make a real difference on climate change?
Yes, but individual action works best with systemic change. High-impact personal steps include eating less beef and lamb, flying less, using renewable energy and avoiding fast fashion, and the IPCC sees demand-side change as one of several levers. Government policy and corporate accountability must deliver most of the scale needed.
Related reading: Climate Change and Sustainable Development | Effects of Climate Change on Human Health | Is Green Hydrogen the Fuel of the Future?
I agree with this article’s emphasis on individual action to combat climate change.