Table 3.

Policy context of common future climate scenarios (Meinshausen et al., 2020; Chen et al., 2021). Scenarios are named by Shared Socioeconomic Pathway (SSPs) and radiative forcing level in 2100, approximating Representative Concentration Pathways (RCPs; W m⁻²).

Scenario	Policy relevance, including global warming levels (GWL) relative to the pre-industrial and corresponding 90% confidence intervals, as assessed by the IPCC Sixth Assessment Report (IPCC, 2021)
SSP1-1.9	A 1.5°C world: an equitable world with sustainable development achieves net zero greenhouse-gas emissions by mid-century and maintains net negative emissions for several decades thereafter. This stabilises global temperatures at 1.4°C (1.0–1.8°C) GWL. Minimal overshoot beyond 1.5 °C is in line with the stretch goal of the Paris Agreement.
SSP1-2.6	A 2°C world: an equitable world with sustainable development achieves net zero emissions around 2075 and maintains net negative emissions for several decades thereafter. Temperatures remain below the target set by the Paris Agreement, being restricted to 1.8 °C (1.3–2.4°C) GWL.
SSP2-4.5	Approximates current climate policies: a world implementing current climate policies and following current trends of slow reduction in consumption and energy use, sees emissions rising until around 2050, before declining to net zero by 2100. Temperatures exceed the Paris Agreement, reaching 2.7°C (2.1–3.5°C) by 2100 and stabilising thereafter. Current nationally determined contributions (NDCs) for 2030 achieve a slightly lower GWL of 2.4°C (1.8–3.4°C) (Hausfather and Moore, 2022).
SSP3-7.0	Approximates a scenario under which no new climate policy is implemented: a world retreating from globalisation to focus on domestic issues deprioritises the environment, resulting in slow economic growth and a doubling of emissions by 2100. Warming reaches 3.6°C (2.8–4.6°C) GWL by 2100 and continues thereafter.
SSP5-8.5	An extreme counterfactual: a world focusing on capitalism, open markets and consumption results in rapid economic growth. Emissions double by 2050 and triple by the end of the century. Warming reaches 4.4°C (3.3–5.7°C) by 2100 and continues thereafter.