Discuss the concept of 'overshoot, peak, and decline' as a climate mitigation pathway. What role can nature-based solutions play in limiting overshoot duration?

The Paris Agreement (2015) commits Parties to hold warming "well below 2°C" and pursue efforts to limit it to 1.5°C [1]. With that threshold now widely assessed as unavoidable to cross, the mitigation debate has shifted from preventing breach to managing it through an 'overshoot, peak, and decline' pathway.

The concept

• Overshoot — global mean temperature temporarily exceeds 1.5°C; UNEP's Limiting Overshoot report treats exceedance as a settled outcome rather than a risk [2].
• Peak — warming crests as deep emission cuts bite; even full implementation of current NDCs and net-zero pledges points to peak warming near 1.8°C [2].
• Decline — net-negative emissions pull temperatures back below 1.5°C, making overshoot temporary rather than permanent [2].
• The pathway is calibrated, not permissive: risks to people and nature rise with both the magnitude and the duration of exceedance [2].

Governance recognition

• COP30's "Global Mutirão" decision (Belém, 2025) is the first COP text to concede likely overshoot, with Parties resolving to limit its magnitude and duration [3].
• It operationalises this through the Global Implementation Accelerator and the Belém Mission to 1.5, both voluntary — reflecting continued reliance on non-binding NDC architecture [3].

Role of nature-based solutions (NBS)

• Carbon removal at scale: large-scale reforestation and afforestation supply the net-negative capacity that shortens the decline phase, since emission cuts alone are insufficient [2].
• Sink protection: halting deforestation guards existing stocks and reduces tipping-point risk in systems like the Amazon [2].
• Co-benefits: mangrove and wetland restoration delivers adaptation and livelihood gains alongside sequestration, aligning with the Mutirão call to close adaptation gaps [3].
• Limits: NBS removals are reversible to fire and drought and cannot substitute for mitigation.

Overshoot management is a second-best strategy forced by ambition deficits, yet it preserves the 1.5°C goal as a return target rather than abandoning it. Pairing rapid decarbonisation with credibly financed, safeguarded nature-based removals offers the most realistic route back below the threshold, advancing SDG 13 and SDG 15 together.