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GPT-5Sep 8, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes
Yes. The overwhelming scientific consensus is that humans are the primary cause of the warming observed since the mid-20th century.
Key evidence:
•Greenhouse gases: CO2, methane, and nitrous oxide from burning fossil fuels, deforestation, and industry have risen to levels not seen in at least 800,000 years.
•Fingerprints of human influence: The pattern of warming (troposphere warming while the stratosphere cools, nights warming faster than days, land warming faster than oceans in the same regions, Arctic amplification) matches greenhouse gas forcing, not solar or volcanic changes.
•Isotopes and oxygen use: The carbon added to the air has a fossil-fuel isotopic signature, and measured declines in atmospheric oxygen match combustion.
•Energy imbalance: Satellites and ocean measurements show Earth taking in more energy than it emits; over 90% of the excess heat is in the oceans.
•Models and observations: Climate models only reproduce the observed warming trend when human emissions are included; natural factors alone cannot.
•Attribution studies: The IPCC concludes it is unequivocal that human influence has warmed the atmosphere, ocean, and land; best estimates attribute essentially all of the observed warming to human activities.
Natural factors (solar variability, volcanoes, internal variability) contribute to short-term ups and downs but cannot explain the long-term global warming trend. For authoritative summaries, see the IPCC Sixth Assessment Report and the U.S. National Climate Assessment.