“Earth has warmed about 1.1°C since 1850–1900, with human greenhouse gases the main driver.”

• IPCC AR6 Working Group I Summary for Policymakers (2021) states global surface temperature in 2011–2020 was 1.09°C [0.95–1.20] above 1850–1900 — the figure commonly rounded to '~1.1°C'.
• The same IPCC assessment attributes 1.07°C [0.8–1.3] of that 1.09°C observed warming to human influence, i.e. essentially all of it, and states 'It is unequivocal that human influence has warmed the atmosphere, ocean and land.' Well-mixed greenhouse gases alone are assessed to have caused about 1.0–2.0°C of warming, partly offset by cooling aerosols.
• Multiple independent surface-temperature datasets (NASA GISTEMP, NOAA NCEI, HadCRUT5, Berkeley Earth, ERA5) agree within roughly a tenth of a degree on the magnitude of warming since the late 19th century, so the number is not dataset-dependent.
• Physical fingerprint evidence supports GHG causation: stratospheric cooling alongside tropospheric warming, greater night-time/winter/Arctic warming, measured increases in downward longwave radiation at CO2 absorption bands, and the isotopic/O2 signature showing the CO2 rise (280→420+ ppm) is from fossil fuel combustion.
• NOAA, NASA, EPA, the Royal Society/US National Academy of Sciences and the WMO all independently endorse both the magnitude and the attribution.
• Natural forcings (solar output, volcanoes) and internal variability cannot reproduce the observed warming in climate models; solar irradiance has been flat-to-slightly-declining since the 1980s while temperatures rose.

• The number is somewhat dated. It describes the 2011–2020 decade. Warming has continued: WMO/Copernicus put 2024 at about 1.5°C above 1850–1900 as a single year, and the current decadal/long-term trend level is nearer 1.2–1.3°C. A present-tense 'has warmed about 1.1°C' understates today's value.
• There is a real uncertainty range (roughly 0.95–1.20°C in IPCC AR6), so '1.1°C' is a central estimate, not a measured constant; early-record (1850–1900) data are sparse, especially over oceans and the Southern Hemisphere, and require infilling.
• Strictly, greenhouse gases alone contributed more warming than 1.1°C (~1.0–2.0°C); roughly 0.0–0.8°C of that was masked by human aerosol pollution and some by land-use change. 'Human greenhouse gases the main driver' is correct but the net human effect is the cleaner statement.
• 1850–1900 is a convenient instrumental baseline, not literally pre-industrial; some warming (order 0.1°C) occurred before 1850, so warming since truly pre-industrial conditions is slightly larger.
• A small minority of scientists argue climate sensitivity is at the low end and that internal variability contributes more than assessed — a position held, but not supported by the weight of attribution studies.

96/100 — the lab’s own confidence in the score above, not a second reading of the claim.

IPCC AR6 Working Group I Summary for Policymakersjournal · 98 · IPCC (AR6 WGI full report landing)journal · 98 · NASA Global Climate Change (GISTEMP)gov · 96 · NASA Science – Scientific Consensusgov · 94 · NOAA Climate.govgov · 95 · World Meteorological Organizationgov · 95 · Copernicus Climate Change Service (ECMWF)gov · 94 · Berkeley Earthother · 88 · Royal Society & US National Academy of Sciencesedu · 95 · NOAA Global Monitoring Laboratory (CO2 record)gov · 97

• IPCC AR6 states that global surface temperature in 2011–2020 was 1.09°C higher than 1850–1900, matching the claim’s “about 1.1°C” wording. It also estimates human-caused warming at 1.07°C over the same baseline, very close to the observed warming.
• IPCC AR6 concludes it is “unequivocal” that human influence has warmed the atmosphere, ocean and land, and identifies well-mixed greenhouse gases as the dominant warming influence, partly offset by aerosol cooling.
• NASA summarizes the evidence similarly: Earth has warmed by about 1.1°C since the late 19th century, and the warming trend is primarily driven by human activities, especially greenhouse-gas emissions.
• NOAA’s global temperature record shows a long-term warming trend since the mid-19th century, consistent with roughly 2°F/about 1.1°C or more total warming depending on period and dataset.

• The main caveat is timing: “about 1.1°C” is most directly supported for the 2011–2020 average used by IPCC AR6. More recent decade-scale estimates are higher; for example, the 2024 WMO assessment reported 2024 at about 1.55°C above 1850–1900 and recent multi-year averages above 1.1°C.
• Some year-to-year or short-period temperature changes are affected by El Niño/La Niña, volcanic aerosols, solar variability and internal climate variability, so not every fluctuation is caused by greenhouse gases. This does not overturn the attribution that human greenhouse gases are the main driver of the long-term warming.
• Different temperature datasets and baseline choices give slightly different numbers, so the exact figure is not a single fixed value. However, the differences are small relative to the claim’s “about” framing.

96/100 — the lab’s own confidence in the score above, not a second reading of the claim.

IPCCother · 98 · IPCCother · 98 · NASAgov · 95 · NASAgov · 95 · NOAA Climate.govgov · 94 · World Meteorological Organizationother · 94 · Earth System Science Datajournal · 93

• The Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) explicitly states that global surface temperature was 1.09°C higher in the 2011-2020 period compared to 1850-1900. It concludes it is 'unequivocal' that human influence has warmed the atmosphere, ocean, and land.
• Independent temperature datasets from NASA, NOAA, and the UK Met Office all show a long-term warming trend consistent with approximately 1.1°C to 1.2°C of warming since the pre-industrial era.
• Attribution studies utilizing climate models demonstrate that natural factors (such as solar irradiance variations and volcanic eruptions) would have caused a slight cooling over the past 50 years. Only the addition of human-caused greenhouse gas emissions (like CO2 and methane) can reproduce the observed rapid warming.

• There is no robust scientific evidence disputing the claim. The scientific consensus overwhelmingly supports both the 1.1°C figure (for the 2011-2020 average) and the conclusion that human activities are the primary driver.
• The only technical counter-argument is that the 1.1°C figure may now be slightly outdated and conservative; with record-breaking heat in recent years (including 2023), the current level of warming is frequently estimated to be closer to 1.2°C or 1.3°C above the 1850-1900 baseline.
• Arguments attributing the bulk of this specific warming trend to natural cycles (like Milankovitch cycles or internal ocean variability) are routinely debunked by isotopic carbon analysis and atmospheric physics.

100/100 — the lab’s own confidence in the score above, not a second reading of the claim.

Intergovernmental Panel on Climate Change (IPCC)gov · 100 · NASAgov · 100 · NOAAgov · 100

• The IPCC states that global surface temperature reached about 1.1°C above the 1850–1900 average in 2011–2020. It concludes that human activities, principally greenhouse-gas emissions, unequivocally caused global warming.[1]
• The IPCC estimates the total human-caused warming from 1850–1900 to 2010–2019 at 0.8–1.3°C, with a best estimate of 1.07°C. It estimates greenhouse gases caused 1.0–2.0°C of warming, partly offset by cooling from other human influences such as aerosols.[2]
• The IPCC estimates natural drivers changed global surface temperature by only −0.1°C to +0.1°C over 1850–2019, while natural variability contributed approximately −0.23°C to +0.23°C. This is much smaller than the roughly 1.1°C observed warming.[3]
• NASA reports that the preponderance of evidence shows human activities, particularly emissions of heat-trapping greenhouse gases, are making Earth warmer.[4]

• The exact value depends on the comparison period and dataset: the IPCC’s estimate for 2010–2019 is 1.07°C, while 1.1°C refers specifically to the 2011–2020 decadal average. Therefore, the wording is an approximation rather than a precise value.[2]
• Greenhouse gases are the main warming driver, but not the only human influence. Aerosols and other human drivers produced a cooling effect, so attributing the entire observed 1.1°C directly to greenhouse gases would be inaccurate.[2]
• Natural variability contributes uncertainty to the measured attribution, with the IPCC estimating a possible contribution of about −0.23°C to +0.23°C over 1850–2019. This does not overturn the conclusion that human influence dominates, but it means the attribution is not exact.[3]

99/100 — the lab’s own confidence in the score above, not a second reading of the claim.

Intergovernmental Panel on Climate Changegov · 99 · Intergovernmental Panel on Climate Changegov · 99 · Intergovernmental Panel on Climate Changegov · 99 · NASAgov · 97

• IPCC AR6 (2021) finds global surface temperature 1.09°C [0.95–1.20°C] higher in 2011–2020 than 1850–1900, with human-caused warming of 1.07°C as the best estimate for 2010–2019.
• Independent instrumental datasets (HadCRUT5, NOAAGlobalTemp, NASA GISS, Berkeley Earth, Copernicus ERA5) all show roughly 1.1–1.3°C of warming from the late-19th-century baseline to the early 2020s.
• Detection-and-attribution studies, multi-model ensembles, and observed fingerprints (tropospheric warming with stratospheric cooling, greater land than ocean warming, energy-budget closure) identify anthropogenic greenhouse gases as the dominant cause; natural forcings and internal variability contribute only a small residual.
• NASA, NOAA, WMO, and national academies of science endorse the same magnitude and attribution.

• Pre-1900 coverage is sparse over oceans and the Southern Hemisphere, so the 1850–1900 baseline carries roughly ±0.1–0.2°C uncertainty.
• Some satellite lower-troposphere series (notably UAH) show a modestly smaller trend than surface thermometers, though they still record statistically significant warming.
• A small minority of researchers contend that urban heat-island residuals, solar/volcanic forcing, or multidecadal ocean cycles explain a larger share of the rise than the IPCC best estimate; these arguments have not displaced the mainstream literature.
• Record warmth in 2023–2024 has moved the current anomaly closer to 1.2–1.3°C in several datasets, so “about 1.1°C” is slightly conservative or slightly dated depending on the exact averaging period.

88/100 — the lab’s own confidence in the score above, not a second reading of the claim.

IPCCother · 97 · NASAgov · 93 · NOAAgov · 92 · Berkeley Earthedu · 88