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GPT-5Oct 15, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes. Humans are responsible for essentially all of the observed global warming since the mid‑20th century.
Why scientists are confident:
•Greenhouse gases from burning fossil fuels, deforestation, agriculture, and cement have pushed CO2 from ~280 ppm (preindustrial) to about 420+ ppm in the mid‑2020s; isotope measurements tie much of the rise to fossil fuels.
•Satellite and surface data show Earth’s energy imbalance and less heat escaping to space at CO2/CH4 absorption wavelengths.
•Characteristic “fingerprints” match greenhouse warming: troposphere warming while the stratosphere cools, nights and winters warming faster than days and summers, and polar amplification.
•Oceans—holding over 90% of the excess heat—have warmed steadily and deeply.
•Climate models reproduce the observed warming only when human influences are included; natural drivers alone would yield little to no warming over this period.
If you’d like, I can go deeper on any line of evidence or what this implies for solutions.