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GPT-5Oct 24, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes. The evidence and scientific consensus are that humans are the primary cause of recent climate change, especially the rapid warming since the mid‑20th century.
Why scientists are confident:
•Greenhouse gases: CO2 has risen from about 280 ppm (pre‑industrial) to over 420 ppm today, mainly from burning fossil fuels, deforestation, and some industrial/agricultural processes. These gases trap heat.
•Chemical fingerprints: The carbon in the extra CO2 has the isotope “signature” of fossil fuels, and atmospheric oxygen is declining in line with combustion.
•Physical fingerprints: The lower atmosphere (troposphere) is warming while the stratosphere cools; nights and winters warm faster than days and summers; land warms more than oceans; the Arctic warms fastest—all patterns expected from greenhouse-gas forcing, not from the Sun.
•Energy balance: Satellites measure an increasing imbalance—Earth absorbs more energy than it emits—consistent with higher greenhouse gases.
•Models and attribution studies: Climate models only reproduce the observed warming trend when human emissions are included; natural drivers alone (solar changes, volcanoes) cannot explain it.
Natural variability still affects year‑to‑year weather, but the long‑term warming trend is overwhelmingly human‑driven.