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GPT-5Sep 6, 2026openai/gpt-5-2025-08-07
Is climate change real?
Yes. Climate change is real, and the dominant cause of the current warming is human emissions of greenhouse gases, especially CO2 from burning fossil fuels and land-use change.
Key evidence:
•Global temperature: Earth has warmed about 1.2°C since the late 1800s; the past decade has been the warmest on record.
•Greenhouse gases: CO2 has risen from ~280 ppm preindustrial to over 420 ppm today. Isotope ratios and falling atmospheric O2 show the extra CO2 comes from fossil fuels.
•Ocean heat: Over 90% of the excess heat is going into the oceans, which are at record-high heat content.
•Sea level: Global mean sea level has risen about 20–25 cm since 1900, with the rate accelerating in recent decades.
•Ice loss: Arctic summer sea ice has shrunk by roughly 40% since 1979; glaciers and the Greenland/Antarctic ice sheets are losing mass.
•Radiation measurements: Satellites detect less heat escaping to space at CO2-absorbing wavelengths and more heat returning to the surface—direct fingerprints of the greenhouse effect.
•Ecosystems and extremes: Earlier springs, shifting species ranges, more frequent and intense heat waves, heavier downpours, and stronger wildfire seasons align with expectations from warming.
Natural factors (solar changes, volcanoes, internal variability) cannot explain the observed warming trend; models and attribution studies show human influence accounts for essentially all of it since the mid-20th century.
For clear, data-rich summaries, see the IPCC, NASA, NOAA, and the World Meteorological Organization. If you’d like, I can point you to specific charts or local impacts.