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GPT-5Sep 17, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes
Yes. The evidence is overwhelming that recent global warming is primarily caused by human activities—mainly burning fossil fuels, deforestation, and certain agricultural practices.
Why scientists are confident:
•Greenhouse gases: CO2 has risen from ~280 ppm (pre‑industrial) to over 420 ppm today, almost entirely from fossil fuels and land-use change.
•Fingerprints: The lower atmosphere is warming while the stratosphere cools; nights and winters warm faster than days and summers; the oceans are accumulating most of the excess heat—patterns expected from greenhouse-gas forcing, not from the Sun or natural cycles.
•Isotopes and oxygen: The carbon added to the air bears the fossil-fuel isotope signature, and atmospheric oxygen declines in line with carbon combustion.
•Energy balance: Satellites measure less heat escaping to space at CO2/CH4 absorption wavelengths, matching laboratory physics.
•Attribution studies: Climate models only reproduce the observed warming trend when human emissions are included; natural factors alone can’t explain it.
•Scale of emissions: Humans emit ~36–40 billion tonnes of CO2 per year, far more than volcanoes, which contribute a small fraction by comparison.
If you’d like, I can share accessible sources (e.g., IPCC AR6, U.S. National Academies) or dive into any point in more detail.