The paper tests one claim: that the carbon dioxide added since about 1850 came from fossil fuels we burned, and that it is the main cause of the warming measured since. The evidence supports it.
Carbon dioxide traps heat
Laboratory measurements since 1859 show that carbon dioxide absorbs the heat the Earth gives off. Adding more raises the height from which the planet loses heat to space. Higher means colder, colder air sheds less heat, and so the surface warms.
The extra carbon dioxide is ours
Carbon dioxide has risen from 278 parts per million in 1750 to about 429 today, higher than at any time in the 800,000 years recorded in Antarctic ice. Four separate tests trace the rise to fossil fuels: it contains no radiocarbon, it carries the chemical signature of ancient plants, oxygen is falling as burning requires, and the air has gained about half of what we are recorded as emitting.
The warming is the greenhouse kind
Extra sunlight would heat the whole atmosphere. Instead, the upper atmosphere is cooling while the lower atmosphere warms, as greenhouse physics predicts. Satellites also measure less heat escaping at carbon dioxide’s wavelengths, and the Sun’s output has been flat or falling since 1980.
What is still uncertain
How much warming each doubling of carbon dioxide brings (best estimate 3 °C, likely between 2.5 and 4 °C), the effect of clouds and air pollution, and why 2023 to 2025 were so hot. These are questions of how much and how fast, not whether.
Where the sceptics were right
Some criticisms had real merit. The famous “hockey stick” graph used a flawed statistical method, a 1988 forecast ran too warm, and the “Climategate” inquiries found scientists had resisted scrutiny. None of them overturns the conclusion, which rests on independent measurements.