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GPT-5Sep 21, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes. The observed warming over the last century is overwhelmingly due to human activities, primarily:
•Burning fossil fuels, which raises carbon dioxide and other heat‑trapping gases.
•Deforestation and agriculture, which add CO₂ and methane and reduce natural carbon sinks.
•Industrial processes that emit additional greenhouse gases.
Key lines of evidence:
•The “fingerprint” matches human causes: the lower atmosphere warms while the stratosphere cools; nights warm faster than days; the Arctic warms faster than the global average.
•Atmospheric CO₂ has the isotopic signature of fossil fuels, and global O₂ has declined as expected from combustion.
•Satellites measure changes in Earth’s energy balance and reduced outgoing heat at CO₂ absorption wavelengths.
•Climate models reproduce the warming trend only when human emissions are included; natural factors alone can’t explain it.
Natural variability affects year‑to‑year fluctuations, but the long‑term warming trend is human‑driven. If you’d like, I can point you to concise summaries from NASA, NOAA, the IPCC, or the U.S. National Climate Assessment.