James Hansen

Global temperature (vs 1880-1920) will stay above +1.5°C at end-2024 and fall at most slightly below +1.5°C in 2025.

“global temperature will remain above +1.5 °C at the end of 2024 and, at most, barely fall below +1.5 °C in 2025.”

Said on

3 February 2025 · Hansen et al., "Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed?", Environment: Science and Policy for Sustainable Development 67:1, published online 3 Feb 2025

Source

Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed? · Environment: Science and Policy for Sustainable Development (Taylor & Francis)

Should come true

2025

How sure they sounded

will (no hedge)

Categories

Climate

Importance

3 of 5 · Test of his ship-aerosol acceleration hypothesis, contested within climate science.

Outcome

Accurate Happened 31 December 2025.

Re-checked on Hansen's own 1880-1920 baseline (GISS-based analysis): 2024 was the record at about +1.57°C, and 2025 came in at +1.47°C, about 0.03°C below +1.5°C, i.e. only barely below as he forecast. The earlier Copernicus (1850-1900) figure gave the same picture, so the score stands.

Evidence:

• https://jimehansen.substack.com/p/global-temperature-in-2025-2026-2027
• https://data.giss.nasa.gov/gistemp/