Context: UNEP’s Limiting Overshoot report projects that the 1.5°C warming limit will likely be temporarily breached in the coming years and outlines a pathway to return below it by 2100.
- Paris Agreement (2015): Seeks to limit global average temperature rise to well below 2°C, while pursuing efforts to limit it to 1.5°C, above pre-industrial levels.
- Overshoot: Temporary warming above 1.5°C, followed by a decline below the threshold by 2100.
- UNEP projections:
- All NDCs + net-zero targets fully implemented → peak warming ~1.8°C.
- Current policies → ~2.6°C by 2100 (range: 1.9–3.6°C).
- Major risks of overshoot: Sea-level rise, coral reef collapse, glacier loss, reduced food production and increased risk of irreversible tipping points.
- Carbon removal: Scaling up nature-based carbon removals, particularly reforestation, would be necessary alongside emission cuts.
- Methane: Responsible for about 0.5°C of warming; reducing methane emissions can slow near-term warming significantly.
- Carbon-removal challenge: Every additional 5 years of high emissions ≈ +0.1°C peak warming; reversing 0.1°C later may require removing about 220 billion tonnes of CO₂.
- COP30, Belém (Brazil), 2025: “Global Mutirão (collective effort)” decision acknowledged the likelihood of a temporary 1.5°C overshoot.
- Prelims Link: The 1.5°C/2°C targets are temperature goals relative to pre-industrial levels, not absolute global temperature limits.
