UNEP: 1.5°C Limit Will Be Overshot, New Path Unveiled

UNVEILS OVERSHOOT PATHWAY AS 1.5°C LIMIT NEARS

Why in the News ?

The UN Environment Programme (UNEP) has outlined an “overshoot, peak and decline” pathway, acknowledging that temporarily crossing the 1.5°C warming threshold is increasingly unavoidable. The strategy aims to minimise the magnitude and duration of overshoot and restore temperatures below 1.5°C by 2100.

UNEP’s Overshoot, Peak and Decline Pathway

•     Inevitable overshoot: UNEP projects that global warming could cross 1.5°C above pre-industrial levels within the next few years, making a temporary breach increasingly unavoidable.
•     Peak containment: Even complete implementation of existing national climate plans and net-zero targets could result in peak warming of around 1.8°C.
•     Current trajectory: Under present policies, global temperatures could rise by about 2.6°C by 2100, indicating a substantial gap between climate commitments and actual emission reductions.
•     Three-stage strategy: The proposed pathway seeks to minimise overshoot, keep temperatures above 1.5°C for the shortest possible period, and subsequently reduce warming below the threshold by 2100.
•     Last-resort approach: UNEP stresses that overshoot is neither desirable nor acceptable as a preferred pathway, but represents the best remaining option if rapid emission reductions are not achieved.

Ecological Costs and Need for Rapid Mitigation

•     Compounding impacts: Prolonged warming beyond 1.5°C can accelerate sea-level rise, coral reef degradation and glacier loss, increasing risks to ecosystems and human societies.
•     Food security: Climate change can substantially reduce global agricultural productivity, particularly where adaptation measures remain inadequate.
•     Tipping-point risks: Higher temperatures increase the possibility of destabilising the Greenland and West Antarctic ice sheets, Amazon ecosystems and Atlantic Meridional Overturning Circulation.
•     Removal challenge: Continued high emissions make subsequent temperature reduction increasingly difficult because larger quantities of atmospheric CO₂ would need to be removed.
•     Methane action: Rapid reductions in methane emissions can provide relatively immediate climate benefits, making methane control an important component of the short-term mitigation strategy.

 Key points : Paris Agreement and Climate Thresholds

•     Paris Agreement: Adopted in 2015, it aims to keep global warming well below 2°C above pre-industrial levels while pursuing efforts to limit warming to 1.5°C.
•     Carbon budget: The concept refers to the limited amount of cumulative CO₂ emissions that can occur while retaining a particular probability of staying below a temperature threshold.
•     Climate tipping points: These are critical thresholds beyond which changes may become self-reinforcing or difficult to reverse, including risks involving major ice sheets, ocean circulation and ecosystems.
•     Carbon dioxide removal: Nature-based removals, such as reforestation, and technological approaches can help remove CO₂ from the atmosphere, but cannot substitute for deep emission reductions.
•     Methane importance: Methane (CH₄) is a potent greenhouse gas with a relatively short atmospheric lifetime; reducing methane emissions can therefore slow near-term warming significantly.