Is it man-made? Follow the fingerprint.
Scientists don't settle this by vote or by authority. They settle it the way a detective does — by giving the natural suspects alibis, and matching the physical evidence to the culprit.
The natural drivers of past climate change — the Earth's orbit, the Sun, volcanoes — each have documented alibis for the warming since the mid-20th century. And the extra carbon dioxide flooding the air carries two fingerprints that point only to burning fossil fuels: a chemical isotope signature, and a specific pattern of warming below and cooling above. This page grades each piece against the primary agency record.
What this page is about
Climate scientists call the method “fingerprinting.” Like a detective, they rule out the innocent suspects and match physical evidence to the culprit. The natural drivers that moved climate in the past each have an alibi for the current warming: the Earth's orbit is nudging us toward slow cooling, not warming; the Sun's output has been flat or slightly down since satellites began measuring it in 1978; and volcanoes emit a small fraction of the carbon dioxide humans do.
Meanwhile, the extra CO₂ itself is marked. Its carbon-isotope makeup shows it came from ancient plant matter — fossil fuels — not from oceans or volcanoes. And the atmosphere is warming in the lower layer while cooling in the upper layer, which is what a greenhouse-gas blanket does and what a brighter Sun cannot. Every pillar here grades FACT against a primary source from NASA, NOAA, the USGS, or the Royal Society.
Books that go deeper on this story. Links are Amazon affiliate searches — buying through them supports the work at no cost to you.
The same investigation, restaged one beat at a time. Step through it here, or present it fullscreen.
Is it man-made? Follow the fingerprint.
Not settled by vote or authority — settled like a crime. The natural suspects (orbit, Sun, volcanoes) have alibis, and the extra CO2 carries the chemical and physical fingerprints of burning fossil fuels.
The natural drivers all have alibis
If the warming were natural, one of the usual drivers would have to be doing it. Each has a documented alibi for the period since the mid-20th century.
| Suspect | If it were guilty… | The alibi (measured) |
|---|---|---|
| Earth's orbit | Slow warming over many millennia | Orbital forcing points to slow cooling; we should be inching toward the next glacial |
| The Sun | Rising solar output | Satellite record since 1978: output flat to slightly down while temperatures rose |
| Volcanoes | Huge CO₂ releases | Emit less than ~2% of human CO₂; humans emit 60+ times more each year |
| The Sun (again) | Whole atmosphere warms evenly | Lower atmosphere warms while upper atmosphere cools — a greenhouse signature, not a solar one |
Sources: NASA (Milankovitch cycles and solar irradiance); NOAA and USGS (volcanic vs human CO₂); Royal Society / U.S. National Academy of Sciences (the stratospheric-cooling fingerprint). Full links in each claim below.
The record, claim by claim
Volcanoes emit far less CO2 than humans — under about 2%, with human emissions 60 or more times greater each year.
FACTA common skeptic claim is that volcanoes out-emit human activity. The measured record is the opposite. The USGS puts global volcanic CO2 at roughly a quarter of a gigaton a year; NOAA states that human activities emit 60 or more times that amount. Human fossil-fuel emissions were about 40 gigatons in recent years — over 100 times volcanic output. Large eruptions can briefly match human emission rates for a few hours, but are far too rare and short-lived to rival the annual human total.
The Sun is not the cause: its measured output has been flat to slightly down since 1978, while temperatures rose.
FACTIf a brightening Sun were driving the warming, solar output would be climbing. It isn't. Total solar irradiance has been measured continuously from space since 1978, and the record shows it flat or slightly declining across recent decades even as global temperatures climbed. A warming Earth under a steady-to-dimming Sun cannot be explained by the Sun.
Earth's orbit points to slow cooling, not warming: absent human influence we would be inching toward the next glacial period.
FACTThe Earth's slow orbital cycles — eccentricity, axial tilt, and precession, together called Milankovitch cycles — drive the ice-age rhythm over tens of thousands of years. Over the past several thousand years these cycles have been on a slow cooling trend, and NASA notes that on their own they would be nudging Earth toward the next glacial period, not warming it. The rapid warming of the last century runs opposite to what the orbit predicts, which is why orbital cycles cannot explain it.
The extra CO2 carries a fossil-fuel isotope signature: atmospheric carbon is getting isotopically lighter, exactly as burning ancient plant matter would make it.
FACTCarbon comes in different weights (isotopes). Plants preferentially take up the lighter carbon-12, so the fossil fuels made from ancient plants are rich in carbon-12 and contain essentially no radioactive carbon-14 (it has long since decayed). As we burn them, the atmosphere's carbon is getting lighter — the share of carbon-13 is falling, and radiocarbon is being diluted (the Suess effect). That is the precise signature of plant-derived fossil carbon, not of CO2 released from oceans or volcanoes. Note the careful wording: it is the proportion of the heavier isotope that is falling, not rising.
The atmosphere is warming below and cooling above — a greenhouse fingerprint the Sun cannot leave.
FACTIf the Sun were the cause, the whole atmosphere would tend to warm together. Instead, the lower atmosphere (the troposphere) is warming while the upper atmosphere (the stratosphere) is cooling. That split is the distinctive signature of greenhouse-gas warming: the gases trap outgoing heat near the surface, leaving less to warm the layers above. This pattern is documented across the satellite temperature record and is one of the clearest ways to tell greenhouse warming from solar warming.
- Royal Society / U.S. National Academy of Sciences — 'Climate Change: Evidence & Causes' (stratospheric cooling as a greenhouse fingerprint)
- IPCC Sixth Assessment Report, Working Group I (2021), Chapter 3 — human influence on the atmosphere (stratospheric cooling)
CO2 is now higher and rising faster than at any point in the 800,000-year ice-core record.
FACTAir bubbles trapped in Antarctic ice cores preserve the atmosphere's composition back about 800,000 years. Across that entire span, CO2 stayed within a band of roughly 170 to 300 parts per million. It is now above 420 ppm — well outside the natural range of the last eight ice-age cycles — and it has risen far faster than at any natural transition, on the order of a hundred times the speed of the increases that ended past ice ages. That is what 'unprecedented' means here: outside the natural range, and rising about a hundred times faster.
Where the evidence is strong, and where it stops
- Attribution is not an opinion poll. The case that humans caused the current warming rests on converging physical measurements — isotopes, solar output, orbital forcing, the warming-below/cooling-above pattern — each of which points the same way. That is why it grades FACT, not because a majority of scientists say so.
- “The climate always changed” is true and beside the point. It did, and the natural drivers that changed it are exactly the suspects ruled out here. That past change had natural causes is not evidence that the present change does; the fingerprints are what settle it.
- The real uncertainty is elsewhere. Scientists genuinely debate climate sensitivity (how much warming a given amount of CO₂ ultimately produces) and the size and timing of specific regional impacts. Those are open questions. Whether humans are the cause is not one of them, and honest writing keeps the two apart.
- We swapped the sources. The popular version of this argument often cites explainer videos. Every claim here is re-anchored to a primary agency source — NASA, NOAA, the USGS, the Royal Society — because on this topic the sourcing is the argument.
A settled question, kept open on purpose
On the narrow question this page asks — is the current warming man-made — the science has been settled for years, by evidence that does not depend on trusting anyone. Yet the public still hears it as a live debate. That gap between what is known and what is believed is not an accident; it is the product of a decades-long effort to manufacture doubt, run with the same method the tobacco industry used. Sorting the real scientific questions from the manufactured ones is the work of The Climate Question hub — and this page is its foundation: before we argue about costs or solutions, we establish what is actually known.
Questions worth taking seriously
Hasn't the climate always changed naturally?
Yes — driven by the orbit, the Sun, and volcanoes, among others. Those are exactly the suspects this page rules out for the current warming. The fact that past changes were natural tells you nothing about the cause of this one; the isotopes, the flat Sun, and the warming-below/cooling-above pattern are what identify the cause, and they point to fossil fuels.
Couldn't it just be the Sun?
No. Total solar irradiance has been measured from space since 1978 and has been flat to slightly declining while temperatures rose. And if the Sun were the cause, the whole atmosphere would warm together; instead the upper atmosphere is cooling. A brighter Sun cannot produce that pattern; more greenhouse gas can.
How do we know the extra CO2 is from us and not the oceans or volcanoes?
Its isotopes. Fossil fuels come from ancient plants, so they're rich in light carbon-12 and contain no carbon-14. As we burn them, the atmosphere's carbon gets isotopically lighter and its radiocarbon is diluted — a signature that matches plant-derived fossil carbon, not the carbon released by oceans or volcanoes. Volcanoes also emit under 2% of what humans do, so they can't account for the rise.
If you are named on this page
If you are named on this page, or are a party materially affected by the claims made here, and you wish to respond, correct the record, or add context, use the Contact page. Responses are published verbatim alongside the original claim, with the sender identified and the date of receipt. The channel stays open for the life of the page.
This site aggregates and grades a record that other outlets and primary sources have already put on the record. Every FACT-graded claim above is sourced to court filings, government reports, sworn whistleblower disclosures, published investigative journalism, or named-source statements. The citations are the accountability mechanism; this section is how you get on the record too.
The record
- Royal Society & U.S. National Academy of Sciences — Climate Change: Evidence & Causes (the basics)
- NOAA Climate.gov — Which emits more CO₂: volcanoes or human activities? (humans 60+ times volcanic)
- USGS — Gerlach (2011), Volcanic versus anthropogenic carbon dioxide
- NASA Goddard — Solar Irradiance (satellite record since 1978)
- NOAA NCEI — Total Solar Irradiance Climate Data Record
- NASA — Milankovitch (Orbital) Cycles and Their Role in Earth's Climate
- NASA — Why Milankovitch Cycles Can't Explain Earth's Current Warming
- NOAA Climate.gov — Climate Change: Atmospheric Carbon Dioxide (isotopes; levels vs the ice-core record)
- NASA — Climate Change: Evidence (ice cores, the 800,000-year record)
- IPCC Sixth Assessment Report, Working Group I (2021), Chapter 3 — human influence on the atmosphere