Science & Media Accuracy

Is Climate Change Real and Human-Caused?

The claim takes two forms: that the world is not warming, or that the warming is natural rather than caused by people. This page tests both against the temperature records, carbon dioxide, the oceans, sea level and ice, and the attribution science that splits the warming by cause. It then compares news coverage with the science.

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✓ Live Last reviewed: Oct 2026 Methodology →

The short answer

Yes, and yes: the world is warming, and people caused it. The planet was about 1.1 °C warmer in 2011 to 2020 than in 1850 to 1900, on four temperature records the Intergovernmental Panel on Climate Change (IPCC) assessed. 2024 was the warmest year yet measured. On the IPCC’s best estimate, people caused all the warming, and the sun and volcanoes likely added at most a tenth of a degree either way. What remains uncertain is how much warming a doubling of carbon dioxide brings: likely 2.5 to 4 °C.

What the Thermometers Show

The records kept by five teams

The temperature record is kept several times over, by five teams with their own methods. One objection is that the record cannot be trusted: towns growing up around weather stations skew it, or a few institutions with a stake in the answer keep it.

In the United States, the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) each build a global series from weather stations, ships and buoys. So do the Met Office with the University of East Anglia in Britain, and the nonprofit Berkeley Earth. The European Copernicus service builds one by feeding observations into a weather model, a method called reanalysis.

Here are four of their figures for 2024, the World Meteorological Organization (WMO) figure combining them with others, and the Intergovernmental Panel on Climate Change (IPCC) assessment of 2011 to 2020:

Global mean surface temperature in 2024 against 1850–1900, by analysis 2024

NASA +1.47 °C

NOAA GlobalTemp +1.46 °C

WMO consolidated estimate +1.55 °C (±0.13)

Copernicus ERA5 +1.60 °C

Berkeley Earth (January 2025 report) +1.62 °C

IPCC AR6 assessment, 2011–2020 average +1.09 °C (very likely 0.95 to 1.20 °C)

Sources: each analysis’s own report for 2024. For the decade, IPCC AR6 WGI, SPM A.1.2 and Chapter 2, an assessment of four records: the Met Office’s HadCRUT5, NOAAGlobalTemp-Interim, Berkeley Earth and Kadow et al.

The 2024 figures run from 1.46 to 1.62 mostly because each analysis sets the 1850–1900 starting line in a slightly different place, as Copernicus explains in its 2024 report. On all eight datasets the WMO uses, the eleven warmest years on record are the last eleven, 2015 to 2025. Agreement among teams using different stations and methods cannot exclude an error they all share. It does exclude an error in one team’s choices.

2024 and the 1.5 °C line

Whether 2024 was the first calendar year above 1.5 °C, the level named in the Paris Agreement, depends on whose analysis you read. It was on Copernicus’s figure and the WMO’s consolidated one, and fell a few hundredths short on NASA’s and NOAA’s.

Berkeley Earth had already put 2023 above the line, at 1.54. Its 2025 report puts 2025 at 1.44. It says 2025 was 0.03 °C cooler than 2023 and about 0.08 cooler than 2024. On those figures 2023 is now about 1.47, below the line.

Global surface temperature against NASA’s 1951 to 1980 average, every second year from 1980 to 2024 (°C)

How to read it: each bar is one year’s global average. The bars are measured against NASA’s 1951 to 1980 average, not the 1850 to 1900 baseline of the 1.5 °C line. So they sit about 0.2 to 0.3 lower than the figures above. In January 2025 NASA put 2024 at 1.28 on this baseline and about 1.47 against 1850 to 1900. Much of the year-to-year wobble is El Niño and La Niña; the climb is the trend.

Global temperature anomaly against 1951 to 1980 (°C), NASA, every second year
Year	°C	Year	°C
1980	0.26	2004	0.53
1982	0.14	2006	0.64
1984	0.16	2008	0.54
1986	0.18	2010	0.72
1988	0.39	2012	0.65
1990	0.45	2014	0.75
1992	0.22	2016	1.01
1994	0.31	2018	0.85
1996	0.33	2020	1.01
1998	0.61	2022	0.89
2000	0.39	2024	1.28
2002	0.63

The urban heat island objection

The objection that towns growing up around weather stations skew the record has been tested directly. Berkeley Earth computed its land average from all 36,869 sites and again from 15,594 sites chosen, by a satellite map, to be far from any urban area. Over 1950 to 2010 the difference between the averages was consistent with no urban heating effect, at −0.10 ± 0.24 °C a century (Wickham et al., 2013).

Cities are often warmer than the country around them, but on the map the study used, urban areas cover only 0.5% of the land.

Satellites, which measure the atmosphere and have no weather stations for buildings to crowd, show its lowest layer, the troposphere, warming as well (Santer et al., 2013).

CO₂ and the Greenhouse Signal

The Mauna Loa record

At Mauna Loa in Hawaii, carbon dioxide averaged 315.98 parts per million (ppm) in 1959, the record’s first full year, and 427.35 in 2025. Before industry it was about 280 ppm, and the 2025 level is higher than at any point in the 800,000 years the ice cores cover.

Measurement there began in March 1958, when Charles Keeling of the Scripps Institution of Oceanography read 313 ppm. The National Oceanic and Atmospheric Administration (NOAA) has kept its own independent record there since 1974. The annual means on this page come from NOAA’s file, which uses Scripps’s measurements up to April 1974.

Atmospheric CO₂ at Mauna Loa Observatory (ppm), NOAA annual means 2010 to 2025

How to read it: one point per year, the annual mean at Mauna Loa in Hawaii (from December 2022 to July 2023, at nearby Maunakea, after an eruption). The vertical axis starts at 385 rather than zero so the rise since 2010 is visible. The whole rise, 37.25 ppm, is 9.5% of the 2010 level, and the line does not turn down in any year.

Mauna Loa annual mean CO₂ (ppm), NOAA, 2010 to 2025
Year	ppm	Year	ppm
2010	390.10	2018	408.72
2011	391.85	2019	411.65
2012	394.06	2020	414.21
2013	396.74	2021	416.41
2014	398.81	2022	418.53
2015	401.01	2023	421.08
2016	404.41	2024	424.61
2017	406.76	2025	427.35

The greenhouse mechanism

Fourier worked out in 1824 that the atmosphere keeps the surface warmer than sunlight alone could. In 1859 Tyndall found out which part of the atmosphere does this, in his laboratory at the Royal Institution in London. Oxygen, nitrogen and hydrogen let infrared radiation through, while water vapour, carbon dioxide and methane absorb it. In 1896 Arrhenius published his calculation of what doubling the carbon dioxide would do to the temperature.

The same absorption shows from orbit, as changes in the infrared leaving the planet in the bands where carbon dioxide and other greenhouse gases absorb (see the fingerprint table below).

The CO₂ "natural fluctuation" argument

Critics are right that carbon dioxide has varied naturally over the 800,000 years the ice cores cover. It ranged between about 180 ppm in ice ages and 280 ppm in the warm periods between them. The difference now is speed. By 2025 the annual mean was about 147 ppm above the pre-industrial 280. NOAA puts the rate of increase over the past 60 years at 100 to 200 times the rate at the end of the last ice age.

How the extra carbon is traced to fossil fuel

Fossil fuels such as coal and oil are ancient plant and animal material, poor in carbon-13 and with no carbon-14 left. So burning them lowers the share of both isotopes in the air, a fall known as the Suess effect. NOAA puts the carbon-13 signature of the atmosphere at about −6.5 parts per thousand before the industrial revolution and about −8 now. The decline has been measured directly since 1978, and in ice cores back to the start of industry (Keeling et al., 2017).

Ocean Heat Content and Sea Level Rise

Where most of the heat goes

Most of the extra heat does not stay in the air. The Intergovernmental Panel on Climate Change (IPCC) finds that ocean warming accounted for 91% of the heating of the climate system from 1971 to 2018.

The heat stored in the upper 2,000 m of the ocean has set a record every year since 2017, nine years in a row. In 2025 alone it rose by about 23 ± 8 zettajoules. It is far less affected than the surface temperature by El Niño and other short-term swings. For that reason a 2026 study calls it “one of the most robust indicators of long-term climate change” (Pan, Cheng et al., 2026).

Sources: Pan, Cheng et al. (2026), on the analysis of the Chinese Academy of Sciences; the CIGAR-RT reanalysis also shows the nine records, and Copernicus Marine’s analysis the 2025 gain. A zettajoule is 10²¹ joules.

Sea level rise

Satellites have measured global sea level since 1993, and by September 2026 they had recorded a rise of 109.8 ± 4.0 mm (NASA). They are a chain of five, from TOPEX/Poseidon to Sentinel-6 Michael Freilich. The rate of rise has more than doubled over that record, from about 2.1 mm a year in 1993 to about 4.5 in 2023 (NASA). The IPCC’s longer series, from tide gauges and satellites, shows it speeding up since 1901.

How fast the sea is rising: millimetres a year, by period

How to read it: each bar is the average rate over its period, so the 2024 and 2025 bars, single years, vary more than the three long ones.

Rate of global mean sea level rise, millimetres a year
Period	mm a year	Source
1901 to 1971	1.3	IPCC AR6
1971 to 2006	1.9	IPCC AR6
2006 to 2018	3.7	IPCC AR6
2024 alone	5.9, against an expected 4.3	NASA
2025 alone	0.8, against an expected 4.4	NASA

Sea Ice, Glaciers and Ice Sheets

Arctic sea ice extent

The September minimum of Arctic sea ice has shrunk by 11.8% a decade from 1979 to 2026, measured against its 1981 to 2010 average. The National Snow and Ice Data Center (NSIDC) has tracked the ice from satellites for nearly 48 years, a record with no surface stations in it.

The 2026 minimum, 4.60 million square kilometres on 12 September, tied 2008, 2010 and 2025 for the tenth lowest. The last 20 years are the 20 lowest in the record. NSIDC adds that there has been no significant decline in the minimum over those two decades.

Global glaciers

The reference glaciers of the World Glacier Monitoring Service (WGMS) have had a negative mass balance, more melt than snow accumulation, every year since 1988, 38 years running. Their losses have grown each decade. WGMS keeps the records of about 60 such glaciers, each with at least 30 years of continuous measurement. 2022 to 2025 were four years in a row with losses above 1 metre of water equivalent. Through 2024, WGMS counted eight of the ten most negative years after 2010.

Glacier mass balance in metres of water equivalent (m w.e.) a year
Period	m w.e. a year
1980s	−0.17
1990s	−0.46
2000s	−0.50
2010s	−0.89
2023, the most negative year on record	−1.23
2024	−1.04
2025	−1.09

m w.e. is the ice lost, expressed as a depth of water. The decade figures are the reference glaciers’ averages that Mauri Pelto reported in State of the Climate in 2019, as the Climate.gov site gives them. The yearly figures are WGMS’s regionalised global averages from his report on 2025.

The Greenland and Antarctic ice sheets

The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) finds that the ice sheets over Greenland and Antarctica added 21.0 ± 1.9 mm to sea level from 1992 to 2020. Their loss rose from 105 billion tonnes a year in 1992–1996 to 372 billion in 2016–2020 (Otosaka et al., 2023).

IMBIE combines estimates from three independent techniques, which measure the height of the ice, weigh it from orbit, and set the snow gained against the ice and meltwater lost. Their estimates spread four times as widely in Antarctica as in Greenland, and on East Antarctica they do not even agree on the sign. IMBIE puts East Antarctica close to balance; the Antarctic loss comes mostly from West Antarctica and less from the Peninsula.

What Is Causing the Warming

The IPCC attribution analysis

Attribution asks how much of the observed warming each cause produced. The 2021 physical-science report of the Intergovernmental Panel on Climate Change (IPCC), which cites more than 14,000 references, gives these figures for 2010–2019 against 1850–1900.

Attribution of the warming from 1850–1900 to 2010–2019 (IPCC AR6, SPM A.1.3 and Figure SPM.2) Likely ranges unless marked

Well-mixed greenhouse gases (CO₂, CH₄, N₂O, halogenated gases) +1.0 °C to +2.0 °C (likely range)

Other human drivers (aerosols, ozone, land-use change), net −0.8 °C to 0.0 °C (aerosols mask part of the greenhouse warming)

All human influences combined +0.8 °C to +1.3 °C (best: +1.07 °C)

Natural drivers (solar + volcanic) −0.1 °C to +0.1 °C

Internal variability (El Niño, ocean cycles) −0.2 °C to +0.2 °C

Observed warming, 2010–2019 vs 1850–1900 +1.06 °C (very likely 0.88 to 1.21)

The fingerprints that tell the causes apart

The table sets each cause’s predicted fingerprints against what was observed.

Fingerprint

Greenhouse gases predict

A brighter sun predicts

Observed

Stratosphere

Cooling

Warming (NASA)

Cooling over the satellite record (Santer et al., 2013); in the lower stratosphere, mostly from human-caused ozone loss to the mid-1990s, and level since in most datasets (IPCC) ✓ human causes

Infrared leaving the planet

Less escaping in the gases’ absorption bands

No change specific to those bands

Changed between the 1970 and 1997 satellite spectra in the bands of carbon dioxide, methane, ozone and chlorofluorocarbons, evidence of a stronger greenhouse effect (Harries et al., 2001) ✓ greenhouse gases

Solar variation

NASA reads the satellite record of the sun’s energy reaching the top of the atmosphere as an 11-year cycle with no upward trend. That record runs from late 1978 and comes from a chain of overlapping instruments. The two rival composites built from those instruments disagree about a two-year gap in 1989 to 1991. So one composite shows a rise from 1980 to 2000, and the other a slight decline. Both show a decline since about 2000, while the surface kept warming.

How the Coverage Compares With the Science

Where coverage tracks science accurately

From 2005 to 2019, most coverage in 17 papers in five countries got the cause right, a study found (McAllister et al., 2021). Of the 4,856 articles it sampled, 2,662 addressed the causes of climate change. Of those, 90% represented the human contribution accurately. Only 2 overstated it, as the sole cause; 263 gave contrarian views equal weight, or denied the warming or that people mainly cause it.

The consensus figure, on whether people cause the warming, comes from surveys of published papers, and it holds. Cook et al. (2013) found that 97% of the 1991 to 2011 abstracts that took a position endorsed human causation. Lynas et al. (2021) drew a random sample of 3,000 from the 88,125 climate papers published from 2012 to 2020. They found four sceptical papers in it. On the 2,718 climate papers in the sample, they put the consensus at 99.85%. They concluded with high statistical confidence that it exceeds 99%.

Framings that go further than the IPCC

Common framings set against the Intergovernmental Panel on Climate Change (IPCC) position
Framing	IPCC position	Assessment
“Climate change causes [specific extreme weather event]”	The IPCC finds human influence already affecting many weather and climate extremes in every region, on evidence that has strengthened since its previous assessment (SPM A.3). Its regional findings run from the 1950s and rest partly on event attribution studies, which test whether one event was made more likely or more intense (Figure SPM.3).	Oversimplified
“We have X years to act or it’s too late”	The IPCC sets no deadline. It says 1.5 and 2 °C will be exceeded this century unless emissions are cut deeply in the coming decades (SPM B.1).	Misleading framing
“1.5°C target” treated as safe threshold	Many changes in the climate system grow in direct relation to the warming (SPM B.2), so they keep growing through 1.5 °C instead of switching on there.	Framing oversimplifies

The false balance problem

In earlier decades much coverage practised false balance, setting the scientific position and its contrarian opponents side by side as if they carried equal weight.

Boykoff and Boykoff (2004) sampled 636 articles from the New York Times, the Washington Post, the Los Angeles Times and the Wall Street Journal, 1988 to 2002. Of the 340 that covered the human contribution, 52.7% gave roughly equal attention to both positions. Another 35.3% emphasised the human role while presenting both. A further 6.2% emphasised doubt, and 5.9% covered only the human role.

The Strongest Case on Each Side

The strongest sceptic case

Argument

Strongest version

Sensitivity

How much warming a doubling of carbon dioxide brings, the equilibrium climate sensitivity, is still a range. The Intergovernmental Panel on Climate Change (IPCC) puts its best estimate at 3 °C. Its likely range is 2.5 to 4 °C, narrower than in its previous assessment. Its very likely range is 2 to 5 °C. The low end would mean much less harm, and a policy sized for the middle would then cost more than needed.

Regional gains

Global averages hide large regional differences. The IPCC records some gains: farm productivity has risen with warming in some high-latitude regions. Some regions have gained from lower energy demand, or in farm markets and tourism (WGII SPM B.1.3 and B.1.6).

Regional variability

Natural drivers and internal variability will modulate human-caused changes, especially at regional scales and in the near term, and planning has to allow for them (IPCC, SPM C.1).

Adapt vs. mitigate

William Nordhaus, who built the Dynamic Integrated Climate-Economy (DICE) model, argued for a “climate-policy ramp”: modest cuts in the near term and sharp ones later. He reviewed the Stern Review on the Economics of Climate Change, which called for sharp immediate cuts. He found that the Review’s call depends decisively on a near-zero social discount rate, 0.1% a year, where his model then started at 3%. The dispute is about economics and ethics: how much a future harm counts today.

The answer

Each of these is an argument about how much harm to expect and what to do about it. None of them disputes the measured warming or its attribution to people. Nor have climate models failed at the global scale. Of 17 projections from 1970 to 2001, 14 were consistent with the warming that followed once errors in their assumed drivers of warming were allowed for (Hausfather et al., 2020).

The strongest case that it is worse than projected

Argument

Strongest version

Tipping points

The central projections may understate the danger. The IPCC says low-likelihood outcomes cannot be ruled out: ice-sheet collapse, abrupt changes in ocean circulation, some compound extremes, and warming well beyond its very likely range. It adds that the probability of such outcomes rises with warming (SPM C.3). Among them is a sea-level rise approaching 2 m by 2100 under very high emissions, above the likely range (SPM B.5.3, low confidence). Deep uncertainty in ice-sheet processes means it cannot be ruled out.

Damage undercounting

The standard cost models may leave the worst out. In its 2013 version, DICE, the model behind the policy ramp, left tipping points out of its damage estimates. Its 2023 version adds a 1% loss of output at 3 °C. In a critique, Keen, Lenton and colleagues quote Nordhaus justifying the omission by his reading of a survey led by Lenton. The critique says the survey in fact warned that warming expected this century was likely to trigger tipping elements.

The answer

These are legitimate arguments about risk, and the IPCC treats low-likelihood outcomes as part of risk assessment (SPM C.3). Which outcomes arrive depends on emissions. By 2100 the likely sea-level rise above the 1995 to 2014 level is 0.28 to 0.55 m on the lowest emissions pathway. On the highest, it is 0.63 to 1.01 m.

The verdict: what the evidence shows

Yes, and yes: the warming is real, and people caused it. Four temperature records, assessed by the Intergovernmental Panel on Climate Change (IPCC), put 2011–2020 at 1.09 °C above 1850–1900. All six analyses the World Meteorological Organization (WMO) combined for 2024 rank it the warmest year measured. The ocean, sea level, sea ice and glaciers show the same change.

The IPCC’s best estimate of the human share of the 1.06 °C observed in 2010–2019 is 1.07 °C. The sun and volcanoes likely account for no more than a tenth of a degree either way. The atmosphere carries the fingerprint of human causes, not of a brighter sun. The stratosphere has cooled while the air below it warmed, which a brighter sun would not do. The infrared leaving the planet has changed in the bands where carbon dioxide and other greenhouse gases absorb.

What is uncertain is how much warming each doubling of carbon dioxide brings and how fast the ice sheets respond, not whether the warming is happening or why.

Five common claims, against the evidence

Claim“Climate change is a hoax, or not real”

FalseThe Intergovernmental Panel on Climate Change (IPCC), assessing four surface records, puts 2011–2020 at 1.09 °C above 1850–1900. On all eight datasets the World Meteorological Organization uses, the eleven warmest years are 2015 to 2025.

Claim“It’s just natural cycles”

FalseThe IPCC’s best estimate puts the human share of the 1.06 °C observed in 2010–2019 at 1.07 °C. The sun and volcanoes likely contributed between −0.1 and +0.1. Natural variability, as climate models simulate it, cannot produce the warmer troposphere and cooler stratosphere that satellites record.

Claim“CO₂ has always fluctuated, nothing unusual”

MisleadingIce cores cover 800,000 years. In that time carbon dioxide ranged between about 180 and 280 parts per million (ppm). The annual mean at Mauna Loa in Hawaii reached 427.35 ppm in 2025. The National Oceanic and Atmospheric Administration puts the rise over the past 60 years at 100 to 200 times as fast as at the end of the last ice age.

Claim“The media exaggerates, it’s not that bad”

Mostly notA study of newspapers in five countries, 2005 to 2019, drew a sample with 2,662 articles on the causes. Of those, 2 overstated the human role; 263 gave contrarian views equal weight, or denied the warming or that people mainly cause it. Some framings of single events, deadlines and the 1.5 °C line go further than the IPCC.

Claim“Scientists keep revising their models, they don’t know anything”

FalseThe IPCC’s best estimate for a doubling of CO₂ is 3 °C. Its likely range, 2.5 to 4, is narrower than before. Of 17 model projections published from 1970 to 2001, 14 were consistent with the warming that followed once errors in their assumed drivers of warming were allowed for.

What would change this conclusion

This article concludes that: (1) the planet warmed about 1.1 °C from 1850–1900 to 2011–2020 on four temperature records; (2) on the IPCC’s best estimate people caused all the warming to 2010–2019, with natural drivers likely within ±0.1 °C; (3) CO₂ is at its highest in at least 800,000 years and over the past 60 years has risen 100 to 200 times as fast as at the end of the last ice age; (4) the ocean, sea level and ice show the same change; (5) past model projections have tracked the warming.

This would change if:

1. The four surface records were shown to share a systematic error of about 1 °C, and the satellite records of the lower troposphere diverged from them.

2. Satellite measurements showed the sun’s energy rising since 1980, or a natural mechanism were found that cools the stratosphere while warming the air below it, or that cuts the heat escaping in the carbon dioxide bands.

3. Isotopic measurements of atmospheric CO₂ stopped matching fossil-fuel carbon, or independent stations diverged from Mauna Loa.

4. The IPCC’s next assessment put the human contribution below half of the observed warming.

5. A published evaluation found most past model projections outside the observed range once actual drivers of warming were used.

Sources

IPCC. Climate Change 2021: The Physical Science Basis, Working Group I Summary for Policymakers (statements A.1.2, A.1.3, A.1.7, A.3, A.4, B.1, B.2, B.5.3, C.1 and C.3, Figure SPM.2); IPCC press release of 9 August 2021. Source for 1.09 °C in 2011–2020 against 1850–1900 (very likely 0.95 to 1.20); the attribution for 2010–2019 (greenhouse gases 1.0 to 2.0, other human drivers 0.0 to −0.8, human total 1.07, likely 0.8 to 1.3, natural ±0.1, internal variability ±0.2, observed 1.06, very likely 0.88 to 1.21); ozone loss behind the lower stratosphere’s cooling from 1979 to the mid-1990s; ocean warming as 91% of the heating from 1971 to 2018; climate sensitivity (best estimate 3 °C, likely 2.5 to 4, very likely 2 to 5); sea-level rates of 1.3, 1.9 and 3.7 mm a year and the likely rise by 2100 by scenario; and the statements on extremes, deadlines, risk growing with warming, regional variability and low-likelihood outcomes. The press release gives the report’s more than 14,000 cited references. ipcc.ch

IPCC. Climate Change 2021: The Physical Science Basis, Working Group I, Chapter 2, Changing State of the Climate System (Gulev et al.). Source for the four surface temperature records the assessment used, which share data and are not fully independent, and for lower-stratosphere temperatures level since the mid-1990s in most datasets. nora.nerc.ac.uk (chapter PDF)

IPCC. Climate Change 2022: Impacts, Adaptation and Vulnerability, Working Group II Summary for Policymakers, statements B.1.3 and B.1.6. Source for the positive impacts on farm productivity in some high-latitude regions, and the positive economic effects in regions that gained from lower energy demand or comparative advantages in farm markets and tourism. ipcc.ch

NOAA Global Monitoring Laboratory. Mauna Loa annual mean CO₂, co2_annmean_mlo.txt (file of 9 October 2026); Scripps Institution of Oceanography, releases of June 2025 and June 2026. Sources for every annual mean from 1959 (315.98) to 2025 (427.35) in the chart and its table, Scripps’s measurements in the file up to April 1974, the readings at Maunakea from December 2022 to July 2023, Keeling’s first reading of 313 ppm on 29 March 1958, and NOAA’s independent record since 1974. gml.noaa.gov

NASA. NASA Analysis Shows Unexpected Amount of Sea Level Rise in 2024, 13 March 2025. Source for the five satellites since 1993, the 2024 rate of 0.59 cm a year against an expected 0.43, and the more-than-doubling of the rate since 1993. nasa.gov

NASA. NASA Analysis Shows La Niña Limited Sea Level Rise in 2025, 29 January 2026. Source for the 2025 rise of 0.08 cm against a long-term expected rate of 0.44 cm a year. nasa.gov

NASA Sea Level Change Portal. Rate of Sea Level Rise Doubled over 30 Years, New Study Shows, 25 February 2025. Source for the rate of rise of about 2.1 mm a year in 1993 and about 4.5 in 2023. sealevel.nasa.gov

World Meteorological Organization. WMO confirms 2025 was one of warmest years on record, 14 January 2026; WMO confirms 2024 as warmest year on record at about 1.55 °C above pre-industrial level, January 2025; Berkeley Earth, Global Temperature Report for 2025. Sources for the eleven warmest years being 2015 to 2025 on all eight datasets the WMO uses, the datasets built from stations, ships and buoys and the two reanalyses; 2024 at 1.55 ± 0.13 on six datasets; and Berkeley’s 2025 at 1.44 ± 0.09, about 0.08 °C below 2024 and 0.03 below 2023. wmo.int

Pan, Cheng et al. Ocean Heat Content Sets Another Record in 2025. Advances in Atmospheric Sciences, 2026. Source for the upper-2,000 m ocean heat content rising about 23 ± 8 zettajoules in 2025 over 2024 on the IAP analysis, the continued gain also shown by CIGAR-RT and Copernicus Marine, the record in each of the nine years 2017 to 2025 on the IAP and CIGAR-RT analyses, and ocean heat content being far less sensitive than the surface temperature to short-term swings, “one of the most robust indicators of long-term climate change”. michaelmann.net (paper PDF)

NSIDC. Arctic sea ice minimum ties for tenth lowest, 23 September 2026. Source for the nearly 48-year satellite record, the 4.60 million square kilometre minimum on 12 September 2026, tied with 2008, 2010 and 2025 for tenth lowest, the last 20 years as the 20 lowest, the decline of 11.8% a decade in the minimum from 1979 to 2026 relative to the 1981–2010 average, and no significant decline over the past two decades. nsidc.org

World Glacier Monitoring Service, Global Glacier State; M. Pelto, Global Alpine Glacier 2025 State of Climate Report (August 2026), the NCAR Climate Data Guide’s page on WGMS observations, and NOAA Climate.gov, Climate change: mountain glaciers (May 2025). Sources for the network of about 60 reference glaciers with at least 30 years of data, their 38th consecutive year of loss, four years in a row above 1 m w.e., the global averages of −1.23 (2023, the most negative), −1.04 (2024) and −1.09 (2025), eight of the ten most negative years after 2010 through 2024, losses growing each decade, and the reference network’s decade averages from State of the Climate in 2019, as Climate.gov reports them (−171 mm a year in the 1980s, −460 in the 1990s, −500 in the 2000s, −889 in the 2010s). wgms.ch

Berkeley Earth. Global Temperature Report for 2024 (January 2025) and Global Temperature Report for 2023; Copernicus Climate Change Service, Global Climate Highlights 2024. Sources for Berkeley’s 1.62 ± 0.06 °C for 2024 and 1.54 for 2023, both above 1.5 on its analysis, and its short-term swings driven mainly by internal variation such as El Niño and La Niña; Copernicus’s 1.60 for 2024, the WMO’s consolidated 1.55 ± 0.13, and the 1.46 to 1.62 spread of the centres’ own 2024 figures, which Copernicus attributes to each centre’s own 1850–1900 estimate. berkeleyearth.org

NOAA Global Monitoring Laboratory. CO₂ at NOAA’s Mauna Loa Observatory reaches new milestone: Tops 400 ppm, 10 May 2013; NOAA Climate.gov, Climate change: atmospheric carbon dioxide, 21 May 2025. Sources for CO₂ varying between about 180 ppm in ice ages and 280 ppm in interglacials over the last 800,000 years, never above 300 ppm in that record, a pre-industrial level of about 280 ppm, and the rate of increase over the past 60 years being 100 to 200 times the rate at the end of the last ice age. gml.noaa.gov

Hausfather, Drake, Abbott and Schmidt. Evaluating the performance of past climate model projections. Geophysical Research Letters, 2020, and co-author Gavin Schmidt’s summary at RealClimate. Source for the 17 model projections published between 1970 and 2001, 14 of them statistically indistinguishable from the warming that followed once errors in their projected forcings were allowed for. realclimate.org

Boykoff and Boykoff. Balance as bias: global warming and the US prestige press. Global Environmental Change 14, 2004; McAllister et al. Balance as bias, resolute on the retreat? Updates & analyses of newspaper coverage in the United States, United Kingdom, New Zealand, Australia and Canada over the past 15 years. Environmental Research Letters 16, 2021. Sources for the 636 articles of 1988 to 2002 and the 340 among them on the human contribution (52.7% balanced, 35.3% emphasising the human role, 6.2% emphasising doubt, 5.9% the human role only), and for the 4,856 articles sampled from 17 papers in five countries, 2005 to 2019, of which 2,662 addressed the causes: 90% accurate, 2 overstating the human role, 263 giving contrarian views equal weight, or denying the warming or that people mainly cause it. scholar.colorado.edu (McAllister et al.)

NASA Science. Sea Level, Earth Indicator, latest measurement September 2026. Source for the satellite record’s rise of 109.8 ± 4.0 mm since 1993. science.nasa.gov

NASA Goddard Institute for Space Studies. GISTEMP v4, Global Land-Ocean Temperature Index (GLB.Ts+dSST), annual means relative to 1951–1980, with data to September 2026. Source for every value in the temperature chart and its table. data.giss.nasa.gov

Scafetta, Willson, Lee and Wu. Modeling Quiet Solar Luminosity Variability from TSI Satellite Measurements and Proxy Models during 1980–2018. Remote Sensing, 2019; NASA Science, Is the Sun causing global warming? Sources for the satellite record of total solar irradiance since 1978 and its instruments, the 1989 to 1991 gap that separates the ACRIM and PMOD composites, ACRIM’s rise to 2000 and decline since, PMOD’s decline throughout, NASA’s reading of no upward trend, and the expectation that a brighter sun would warm every layer of the atmosphere, the stratosphere included. ntrs.nasa.gov

Harries, Brindley, Sagoo and Bantges. Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997. Nature 410, 2001. Source for the changes in the outgoing infrared between the 1970 and 1997 satellite spectra in the bands of carbon dioxide, methane, ozone and chlorofluorocarbons, direct evidence of a stronger greenhouse effect. doi.org/10.1038/35066553

NASA. Temperatures Rising: NASA Confirms 2024 Warmest Year on Record, 10 January 2025. Source for 2024 at 1.28 °C above NASA’s 1951–1980 baseline and about 1.47 above 1850–1900. nasa.gov

NOAA National Centers for Environmental Information. Assessing the Global Climate in 2024, January 2025. Source for 2024 at 1.46 °C above the 1850–1900 average, the warmest year in NOAA’s record from 1850. ncei.noaa.gov

IPCC AR6 WGI, Figure 2.11 data, Centre for Environmental Data Analysis (curated on behalf of the IPCC Data Distribution Centre). Source for the four global surface temperature datasets the assessment used: HadCRUT5, NOAAGlobalTemp-Interim, Berkeley Earth and Kadow et al. catalogue.ceda.ac.uk

Otosaka et al. Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020 (IMBIE). Earth System Science Data 15, 2023. Source for the three techniques, the 21.0 ± 1.9 mm contribution to sea level, the loss rising from 105 to 372 billion tonnes a year, the Antarctic loss mostly from West Antarctica and less from the Peninsula, East Antarctica close to balance and the most uncertain part, the spread of the techniques’ estimates four times wider in Antarctica than in Greenland, and their disagreement on East Antarctica’s sign. essd.copernicus.org

NOAA Global Monitoring Laboratory. The Data: What 13C Tells Us; Keeling et al. Atmospheric evidence for a global secular increase in carbon isotopic discrimination of land photosynthesis. PNAS, 2017. Sources for fossil fuels being ancient plant and animal material, poor in carbon-13 and with no carbon-14, the atmosphere’s carbon-13 signature falling from about −6.5 to about −8 parts per thousand, the Suess effect, and the decline measured directly since 1978 and in ice cores since the industrial revolution. gml.noaa.gov

Science History Institute. Future Calculations, Distillations magazine. Source for Fourier’s calculation of 1824, Tyndall’s laboratory measurements of 1859 at the Royal Institution (oxygen, nitrogen and hydrogen transparent to infrared; water vapour, carbon dioxide and methane absorbing it) and Arrhenius’s doubling calculation, published in 1896. sciencehistory.org

Wickham, Rohde, Muller et al. Influence of Urban Heating on the Global Temperature Land Average using Rural Sites Identified from MODIS Classifications. Geoinformatics & Geostatistics: An Overview 1(2), 2013 (Berkeley Earth). Source for the 36,869 sites, the 15,594 rural sites distant from urban areas, the difference over 1950 to 2010 of −0.10 ± 0.24 °C a century, consistent with no urban heating effect, and urban areas making up 0.5% of the land area. berkeleyearth.org (paper PDF)

Santer et al. Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences 110, 2013. Source for the satellite record’s tropospheric warming and stratospheric cooling since the late 1970s, a pattern that natural variability, solar changes included, cannot produce as climate models simulate it. pubmed.ncbi.nlm.nih.gov

Nordhaus. The Stern Review on the Economics of Climate Change. NBER Working Paper 12741, 2006, and A Review of the Stern Review on the Economics of Climate Change, Journal of Economic Literature 45, 2007; Barrage and Nordhaus. Policies, projections, and the social cost of carbon: Results from the DICE-2023 model. Proceedings of the National Academy of Sciences 121, 2024; Keen, Lenton et al. Economists’ erroneous estimates of damages from climate change, 2021 (arXiv preprint). Sources for the climate-policy ramp, the Stern Review’s social discount rate of 0.1% a year against DICE’s then starting rate of 3%, the dependence of the Review’s conclusions on that rate, the 2023 version’s 1% loss of output at 3 °C from tipping points, Nordhaus’s justification, as Keen and colleagues quote it, for leaving tipping points out of damage estimates, and their reading of the survey he cited. nber.org

Lynas, Houlton and Perry. Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature. Environmental Research Letters 16, 2021; Cook et al. Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters 8, 2013. Sources for the sample of 3,000 papers from 88,125, the four sceptical papers, the 99.85% consensus on the 2,718 climate papers in the sample and the conclusion, with high statistical confidence, that it exceeds 99%, and Cook’s 97% of the 1991 to 2011 abstracts that took a position. doi.org/10.1088/1748-9326/ac2966

Cite this article TruthBased.org. “Is Climate Change Real and Human-Caused?” Updated October 2026. https://www.truthbased.org/is-climate-change-real-and-human-caused