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GPT-5Sep 18, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes. Humans are the primary cause of the warming observed since the mid‑20th century.
Why scientists are confident
•Greenhouse gases from burning fossil fuels, deforestation, and agriculture have raised CO2 from ~280 ppm (pre‑industrial) to about 420+ ppm today, trapping more heat.
•The “fingerprints” match a greenhouse‑driven change: the lower atmosphere warms while the stratosphere cools; nights warm faster than days; the poles (especially the Arctic) warm fastest.
•Energy measurements show a persistent Earth energy imbalance and rapidly rising ocean heat content (where >90% of the excess heat goes).
•Climate models reproduce the observed warming only when human emissions are included; natural factors alone (solar and volcanoes) cannot explain the long‑term trend.
•Attribution studies find that human factors account for essentially all of the net warming since 1950; aerosols from pollution masked some warming, so the human contribution is >100% of the observed rise, with natural variability adding short‑term ups and downs.
What about natural cycles or the Sun?
•Solar output has shown no sustained increase that could explain recent warming.
•Volcanic eruptions cool the climate temporarily.
•Internal variability (e.g., El Niño/La Niña) shifts heat around and affects year‑to‑year temperatures but does not create the decades‑long warming trend.
In short: it is unequivocal in the scientific assessments (e.g., IPCC, U.S. National Climate Assessment) that recent climate change is driven by human activities.