The retirement of RCP8.5 has been described as both a scientific milestone and a potential source of policy complacency. Critically examine.

Q. The retirement of RCP8.5 has been described as both a scientific milestone and a potential source of policy complacency. Critically examine. (15 marks, 250-350 words)

RCP8.5 — the high-forcing pathway (8.5 W/m² by 2100) that IPCC's AR6 assessed as yielding 3.3°C–5.7°C of warming [1] — has been retired as implausible by modellers ahead of AR7 [2]. The decision is scientifically defensible, but its policy signalling cuts both ways.

As a scientific milestone - Evidence over assumption: collapsing solar costs and record renewable additions, led by China, make a fossil-intensive 8.5 W/m² world unrealistic; scenarios now reflect observed cost curves and enacted policy. - Course correction: RCP8.5 was built as a stress test, yet was routinely reported as "business as usual"; AR6 had already placed it at the low-likelihood high end [1]. - Better architecture: seven new scenarios embed socio-economic narratives alongside physics, giving AR7 a more usable risk range [2]. - Wider ownership: Indian participation in the modelling exercise (IISc's Prof. G. Bala) reflects broader representation in earth-system science [5].

Why complacency is a real risk - Only the tail is gone: current policies still point to roughly 2.8°C by 2100 [3], far above the Paris goals of 1.5°C and well below 2°C; the new worst case (~3.5°C) remains catastrophic. - Thresholds persist: such warming still risks ice-sheet loss, permafrost thaw and monsoon disruption — directly threatening India's coasts, water security and farm incomes. - Conditional, not permanent: implausibility rests on continued renewable scale-up; policy reversal or slowed deployment could revive high-emission trajectories. - Signalling danger: "worst case ruled out" headlines may dilute ambition precisely when AR7 is to inform the next NDC cycle [2]. - India's record argues otherwise: 50% non-fossil installed capacity, achieved ahead of the 2030 NDC target [4], shows that action — not reassurance — moves outcomes.

Retiring RCP8.5 is best read as vindication of climate policy, not exoneration from it: the danger zone has narrowed, not closed. The realistic response is to ratchet NDCs, scale climate finance and strengthen adaptation, so that scenario realism becomes a spur to action on SDG-13 rather than a licence for delay.

(~325 words)

Sources: 1. IPCC AR6 WG-I, Summary for Policymakers (2021) — SSP5-8.5/RCP8.5 forcing level and 3.3–5.7°C projected warming; its low-likelihood status 2. IPCC News Comment on Scenarios (May 2026) — retirement of the highest-emission scenario and new scenario set feeding AR7 3. UNEP, Emissions Gap Report 2025 — current-policies warming trajectory of about 2.8°C by 2100 4. PIB, India's Updated Nationally Determined Contribution (Aug 2022) — 50% non-fossil installed electricity capacity target for 2030 5. "Scientists rule out worst-case climate scenario, with caution" — The Hindu, 7 June 2026 (link not machine-verifiable) — Indian participation via IISc's Centre for Atmospheric and Oceanic Sciences