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GPT-5Sep 20, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes. Humans are the primary cause of the rapid warming observed since the mid‑20th century.
Why scientists are confident:
•Physics: Adding greenhouse gases (CO2, methane, nitrous oxide) reduces Earth’s heat loss to space, raising temperatures—this is well‑tested radiative physics.
•Fingerprints: The lower atmosphere warms while the stratosphere cools; nights and winters warm faster than days and summers; land warms faster than oceans—patterns expected from greenhouse gases, not from the Sun.
•Measurements: Atmospheric CO2 has risen by about 50% since preindustrial times, with an isotopic “fossil‑fuel” signature and a measured decline in atmospheric O2 from combustion.
•Energy imbalance: Satellites and ocean measurements show Earth taking in more energy than it emits; over 90% of the excess heat is accumulating in the oceans.
•Models: Climate models only reproduce the observed long‑term warming when human influences are included; natural factors alone (solar cycles, volcanoes) cannot explain it.
•Consensus: Major scientific assessments (e.g., the IPCC’s Sixth Assessment Report, 2021–2023) conclude it is “unequivocal” that human activities have warmed the atmosphere, ocean, and land.
Natural variability still affects year‑to‑year conditions, but the long‑term warming trend is driven by human emissions and land‑use change. If you’d like, I can point you to accessible summaries and primary sources.