Scientists have understood the basic science of climate change for a long time. Eunice Newton Foote and John Tyndall described the greenhouse effect in the 1850s, and Svante Arrhenius calculated the effect of CO2 in 1896. What is new is the observed evidence: global temperature records, sea-level data, ice cores, extreme weather studies and ecosystem change all confirm the projections. This post sets out ten facts from the IPCC Sixth Assessment Report, the World Meteorological Organization (WMO) and recent studies, updated with 2025 and 2026 data.
Summary
- 2024 was the first calendar year above 1.5°C (about 1.55°C), and 2025 was the second or third warmest year at 1.44°C, according to the WMO. The years 2023 to 2025 were the three warmest on record.
- The IPCC AR6 states that it is unequivocal that human influence has warmed the atmosphere, ocean and land.
- Atmospheric CO2 reached 423.9 ppm in 2024, the highest in at least 2 million years, according to the WMO.
- The remaining carbon budget for a 50% chance of staying below 1.5°C was estimated at 130 GtCO2 from the start of 2025, a little over three years of current emissions. The 2025 Global Carbon Budget puts it at 170 GtCO2, about four years.
- Policy has moved: the EU set 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.
Fact 1: Is 1.5°C of global warming already here?
Single years have passed it, and the long-term average is close. The Paris Agreement set 1.5°C above pre-industrial levels as its aspirational limit. The WMO confirmed 2024 as the first calendar year above 1.5°C, at about 1.55°C. For 2025, the WMO’s consolidated analysis of eight datasets gave 1.44°C, ranking it second or third warmest, and the 2023 to 2025 average was 1.48°C. The Copernicus service reported 2025 as the end of the first three-year period averaging 1.5°C. The Paris limit refers to a multi-decade average, so it has not formally been breached, but limiting warming to 1.5°C without temporary overshoot now looks very difficult. The IPCC says that staying on a 1.5°C path requires emissions to peak before 2025 and fall 43% by 2030 relative to 2019.
Fact 2: Are humans unequivocally the cause of climate change?
Yes. The IPCC AR6 Working Group I report (2021) states that it is unequivocal that human influence has warmed the atmosphere, ocean and land. The main driver is the burning of coal, oil and gas, with additional contributions from agriculture, deforestation and industry. The WMO reports that CO2 rose from about 278 ppm in 1750 to 423.9 ppm in 2024, a 53% increase and the highest level in at least 2 million years. The 2023 to 2024 rise of 3.5 ppm was the largest in the modern record.
Fact 3: Is the last decade the hottest on record?
Yes. The WMO confirmed that the 11 years from 2015 to 2025 are the 11 warmest in the 176-year record. The Arctic warms roughly four times faster than the global average, with consequences for sea ice, permafrost and ocean circulation.
Fact 4: How fast are sea levels rising?
The rate has accelerated. Global mean sea level has risen about 20 cm since 1900, driven by thermal expansion and melting glaciers and ice sheets. The WMO reports that the average rate of rise doubled between 2016 and 2025 compared with the 1990s, reaching about 4.1 mm a year. The IPCC projects 0.63 to 1.01 m by 2100 under high emissions, with low-likelihood scenarios of 1.5 to 2 m if ice sheet instabilities are triggered. Around 1 billion people live in low-elevation coastal zones.
Fact 5: Are extreme weather events getting worse?
Yes. Attribution science now shows that climate change has made heatwaves more frequent and intense, and has affected heavy rainfall, droughts and the strongest tropical cyclones. Munich Re estimated that weather-related insured losses exceeded USD 100 billion for the fifth year in a row in 2023. For insurers, infrastructure planners and risk managers, the central problem is non-stationarity: historical weather data no longer predict future hazard probabilities reliably.
Fact 6: What is happening to the ocean?
The ocean absorbs more than 90% of the excess heat trapped by greenhouse gases, and roughly a quarter to a third of annual human CO2 emissions. The heat drives marine species poleward, bleaches coral reefs and changes fisheries. The CO2 forms carbonic acid, and ocean pH has fallen by about 0.1 units since pre-industrial times, which means roughly 26% more acidity. This harms corals, molluscs and the base of marine food webs.
Fact 7: How much carbon budget is left?
Very little for 1.5°C. A carbon budget is the cumulative CO2 that can still be emitted for a given chance of staying below a temperature limit. The IPCC AR6 estimated about 500 GtCO2 from January 2020 for a 50% chance at 1.5°C. The Indicators of Global Climate Change study (published in June 2025) puts the central estimate at 130 GtCO2 from the start of 2025, which is exhausted in a little over three years at current emissions. The 2025 Global Carbon Budget gives 170 GtCO2, about four years at 2025 emissions, and calls the 1.5°C budget virtually exhausted. For 2°C, the budget is about 1,050 GtCO2, or 25 years at 2025 emission levels. Estimates differ with method, but they agree on the main message.
Fact 8: Who suffers most from climate change?
Those who contributed least. Small island developing states, sub-Saharan Africa and South and Southeast Asia face sea level rise, heat stress, drought and falling crop yields. The IPCC AR6 Working Group II report found that about 3.3 to 3.6 billion people live in contexts highly vulnerable to climate change. Climate justice, the principle that the burden of action and adaptation should reflect responsibility and vulnerability, is now central to negotiations and to sustainability governance.
Fact 9: Do we already have the solutions to climate change?
Largely, yes. The IPCC AR6 Working Group III report (2022) found that the technical and economic options to limit warming to 1.5°C or 2°C are available, and often cost-effective. Solar and wind are the cheapest new electricity sources in most of the world, and electric vehicle adoption is accelerating. The gap lies in policy and investment: current policies point to roughly 2.5 to 3°C of warming by 2100, far above the Paris goal.
Policy direction differs across our four main markets:
- EU and Germany: Regulation (EU) 2026/667 amended the European Climate Law in March 2026 to set a binding 90% net emission reduction target by 2040 compared with 1990, with up to 5% from international carbon credits and a one-year delay to ETS2, now due in 2028.
- UK: the Climate Change Act 2008 sets legally binding carbon budgets and a net zero 2050 target.
- US: the withdrawal from the Paris Agreement took effect on January 27, 2026, and the administration has also moved to leave the UNFCCC and the IPCC. California SB 253 requires emissions reports from large companies by November 10, 2026.
- Canada: the Canadian Net-Zero Emissions Accountability Act sets 2050 net zero and five-year milestones. The consumer fuel charge ended in April 2025, while industrial carbon pricing continues.
Fact 10: Does every fraction of a degree really matter?
Yes. Every tenth of a degree avoided means fewer people exposed to lethal heat, lower chances of coral reef collapse, fewer extreme rainfall events and greater food system stability. At 1.5°C, 70 to 90% of warm-water coral reefs face severe pressure, and at 2°C virtually all face long-term decline. For what organisations can do, see our posts on ESG reporting frameworks, SBTi target setting and sustainability assessment methods.
Frequently Asked Questions: Climate Change in 2026
What is the IPCC and why should I trust its findings?
The Intergovernmental Panel on Climate Change (IPCC) is a UN body that assesses climate science. It does not run its own experiments. It reviews peer-reviewed literature written by thousands of scientists, and every report goes through several rounds of expert and government review. AR6 was completed in 2022 and 2023.
Has the 1.5°C target already been breached?
Single years have exceeded it, but the Paris limit refers to a long-term average, so it has not formally been crossed. The WMO put 2024 at about 1.55°C and 2025 at 1.44°C, and the 2023 to 2025 average at 1.48°C.
What is a carbon budget?
It is the total CO2 that can still be emitted while keeping a stated chance of staying below a temperature limit. The 1.5°C budget is estimated at 130 to 170 GtCO2 from 2025, which is three to four years of current emissions.
What is climate attribution science?
It compares the probability of an extreme event in today’s climate with a counterfactual climate without human emissions. It can now attribute individual heatwaves, floods and droughts to climate change with quantified confidence.
What can individuals and organisations do about climate change in 2026?
Individuals have the most impact by flying less, eating less meat, using renewable electricity and supporting stronger policy. Organisations should measure Scope 1, 2 and 3 emissions, set science-based targets, and integrate climate risk into reporting, for example under the CSRD (companies over 1,000 employees and EUR 450 million turnover after Omnibus I), California SB 253 and the UK Sustainability Reporting Standards.
Related reading: Why Biodiversity Is the Backbone of a Stable Global Economy | GRI vs SASB vs TCFD vs ISSB: ESG Reporting Frameworks | Why Sustainability Assessment Matters | Air Pollution and Respiratory Health in Urban India
The media exaggerates these things… I’m currently working on an article about the new report of the IPCC and on how the media shapes public perception on this subject. Monday it will be online.