SSP Climate Scenario Comparator

SSP Scenario

Compare all four at once

Model Parameters

Climate sensitivity ECS 3.0 °C

Ocean heat uptake κ 0.70 W/m²/K

Mitigation pace τ 35 yr

Playhead year 2020

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Radiative forcing F(t)

2.20 W/m²

Surface ΔT

0.00 °C

Deep-ocean ΔT (thermal lag)

0.00 °C

How it works

Each SSP-x.y name is literally its target: the total anthropogenic radiative forcing (W/m², relative to pre-industrial) that pathway reaches by 2100. Forcing is driven toward that target with an exponential approach set by the mitigation-pace slider τ:

F(t) = F₀ + (F_target − F₀) · (1 − e^(−(t−2020)/τ))

Temperature response uses the two-layer energy-balance model behind most simplified climate emulators (e.g. Held et al. 2010): a fast surface/upper-ocean box (T₁) exchanges heat with a slow deep-ocean box (T₂), which is why warming lags forcing for decades.

C₁ dT₁/dt = F(t) − λT₁ − κ(T₁−T₂)
C₂ dT₂/dt = κ(T₁−T₂)
λ = F₂ₓ / ECS   (F₂ₓ ≈ 3.8 W/m² per CO₂ doubling)

ECS — equilibrium climate sensitivity: equilibrium warming per CO₂ doubling. Higher ECS means a smaller λ, so the same forcing produces more warming.
κ — ocean heat uptake efficiency. A larger κ pulls more heat into the deep ocean, damping and delaying surface warming (and storing energy for later release).
τ — how many years it takes forcing to close most of the gap to its 2100 target; slower mitigation means the same endpoint is reached with a sharper, later ramp.

Bars along the timeline are colour- and height-coded by surface ΔT for each 5-year step; the glowing marker tracks the playhead year, and the line above the bars traces the smooth ΔT(t) curve the two-box model produces.

SSP1-2.6 SSP2-4.5 SSP3-7.0 SSP5-8.5

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