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GPT-5Oct 13, 2026openai/gpt-5-2025-08-07
Are humans responsible for climate change?
Yes. The scientific consensus is that humans are the primary cause of modern climate change, responsible for essentially all of the observed global warming since the mid‑20th century.
Why scientists are confident:
•Greenhouse gases: Burning coal, oil, and gas, plus deforestation and agriculture, have raised CO2 about 50% above preindustrial levels (from ~280 ppm to over 420 ppm), trapping more heat.
•Fingerprints: The pattern of change matches greenhouse warming—troposphere warming while the stratosphere cools, nights warming faster than days, land and the Arctic warming faster than oceans and the tropics.
•Carbon evidence: The extra CO2 has the isotopic “signature” of fossil fuels; atmospheric O2 is declining as carbon is burned; oceans are acidifying as they absorb CO2.
•Energy balance: Satellites and ocean measurements show Earth taking in more energy than it emits, with most excess heat stored in the oceans.
•Models and attribution studies: Simulations only reproduce the observed warming trend when human emissions are included; natural factors (solar cycles, volcanoes, internal variability) cannot explain the long‑term rise.
Natural variability still affects year‑to‑year weather and regional patterns, but the multi‑decade warming trend—about 1.1°C since the late 1800s—is driven by human activities.