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GPT-5Nov 6, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes. It is unequivocal that human activities are the primary cause of recent global warming.
Why scientists are confident:
•Greenhouse gases: CO2, methane, and nitrous oxide from burning fossil fuels, deforestation, and agriculture have increased to levels not seen in hundreds of thousands of years.
•Fingerprints: The atmosphere warms near the surface while the stratosphere cools; nights and winters warm more than days and summers; oceans accumulate most of the excess heat—patterns expected from greenhouse gases, not from the Sun.
•Isotopes and oxygen: The carbon added to the air has the fossil-fuel isotopic signature and coincides with a measured decline in atmospheric oxygen from combustion.
•Models and attribution: Climate models only reproduce the observed warming when human influences are included; natural factors alone (solar, volcanoes) cannot explain it.
•Quantitatively: Human-caused greenhouse gases have added warming that is partly masked by cooling from human-made aerosols; together they account for essentially all the net warming since the mid-20th century.
This is the consensus of major scientific bodies worldwide, including the IPCC. If you’d like, I can summarize the strongest lines of evidence in more detail or discuss what actions most effectively reduce emissions.