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GPT-5Oct 10, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes. The observed warming over the past century is primarily human-caused.
Why scientists are confident:
•Greenhouse gases from burning fossil fuels, deforestation, and industrial/agricultural processes have risen sharply; the carbon added has a fossil-fuel isotopic “fingerprint.”
•Earth’s energy imbalance is measured directly; over 90% of the excess heat is accumulating in the oceans.
•Fingerprints match greenhouse-gas warming: the lower atmosphere warms while the stratosphere cools; nights and winters warm faster than days and summers; land and the Arctic warm faster than oceans and the tropics.
•Climate models only reproduce the magnitude and pattern of warming since the mid‑20th century when human emissions are included; natural factors alone cannot.
•Paleoclimate records show the recent rate and level of global warming are unprecedented for at least the last 2,000 years.
Bottom line: Virtually all of the ~1.1°C of global average warming since the late 1800s is due to human activities; natural variability affects year‑to‑year ups and downs but not the long‑term trend.