IPCC AR6 WG1 Headline Statements (2021)

TL;DR — The IPCC’s two-page list of top-line findings from its 2021 assessment of the physical science of climate change, in four parts: present state, futures, risk and limiting warming.

The document gives the headline statements from the Summary for Policymakers of Working Group I’s contribution to the IPCC Sixth Assessment Report (AR6), released in August 2021. It has fourteen numbered statements in four sections.

A. The current state of the climate. It is “unequivocal” that human influence has warmed the atmosphere, ocean and land. Recent changes are unprecedented over many centuries to many thousands of years. Human-caused change already affects extremes such as heatwaves, heavy rain, droughts and tropical cyclones in every region, and the evidence linking them to human influence has grown since AR5. The best estimate of equilibrium climate sensitivity is 3°C, with a narrower range than in AR5.

B. Possible climate futures. Surface temperature keeps rising until at least mid-century under every scenario considered, and 1.5°C and 2°C will be passed this century unless CO2 and other greenhouse-gas emissions fall deeply in the coming decades. Extremes grow in step with warming, the water cycle intensifies, and land and ocean carbon sinks absorb a smaller share of CO2 as emissions rise. Many changes, especially to the oceans, ice sheets and sea level, cannot be reversed for centuries to millennia.

C and D. Risk and limits. Natural variability changes regional outcomes in the near term but has little effect on warming over a century. Low-likelihood outcomes such as ice-sheet collapse or abrupt changes in ocean circulation cannot be ruled out. Limiting warming requires limiting cumulative CO2 emissions, reaching at least net zero CO2, and cutting other gases sharply, including methane. Under low-emission scenarios, differences in global temperature trends would emerge from natural variability within about 20 years.

What it is: the official summary of the physical-science consensus, approved line by line by member governments. It carries a lot of weight as a statement of consensus, but it is only a summary. The detail and the confidence levels are in the full report’s chapters.

Where this came from

• Saved in an August 10, 2021 daily note, reached through a newsletter link, with notes copying out sections A and B under Climate Change.
• Published openly by the IPCC: ipcc.ch (checked 2026-10-27, HTTP 200).

2 pages. A copy is archived locally against link rot; the header links the original source.