UNEP Report on Limiting Climate Overshoot Beyond 1.5°C
Why in the news
UNEP released its Limiting Overshoot report (subtitle: navigating exceedance of 1.5°C and pathways towards return), asking how the world could drop back below the limit after crossing it for a while.
Key facts
- Climate overshoot: temperature goes past 1.5°C for a while, peaks, then declines. Stages: exceedance, plateau or peak, decline, stabilization.
- Warming from human activity is about 1.4°C and growing roughly 0.25°C per decade.
- WMO sees a 75% likelihood of the 2026-2030 average topping 1.5°C.
- Only about 130 GtCO₂ of carbon budget is left for a coin-flip chance of holding 1.5°C; at present emissions it may be used up in around 3 years.
- Existing policies lead towards about 2.6°C by 2100; full NDC and net-zero delivery would still peak near 1.8°C.
Cost of delay
- Five more years of heavy emissions add roughly 0.1°C to the peak.
- Reversing it needs about 220 GtCO₂ removed from the air.
Risks flagged
| Area | Risk |
|---|---|
| Tipping points | Greenland and West Antarctica ice melt, weaker AMOC, Amazon dieback |
| Glaciers | Over 25% of mountain glacier mass may vanish by 2100 |
| Sea level | Around 40 cm more by 2300 for each century above 1.5°C |
| Food | Production may fall by as much as 14% by 2050 if adaptation is weak |
| Coral reefs | Repeated heavy bleaching may overwhelm them |
Concerns
- Debt stress from rebuilding costs.
- DACCS and BECCS removal is resource-hungry; nature-based removal can saturate.
- Maladaptation, island states like Tuvalu and Kiribati, humid heat.
Way forward
- Pair mitigation with adaptation; scale renewables and phase down fossil fuels.
- Cut methane fast; strengthen MRV for removal projects, which only supplement emission cuts.
- Resilient infrastructure and more Loss and Damage finance.
Exam angle
- Issuer: UNEP. Terms: overshoot, carbon budget, DACCS, BECCS, MRV.