Every glowing pillar around the globe is a negotiating country. Roughly every five simulated years a "COP round" fires: each country files a Nationally Determined Contribution (NDC) — a pledged emissions cut proportional to the global ambition slider, scaled by that country's own resolve (fixed, randomly assigned at reset, mirroring how some economies negotiate deeper cuts than others). Whether a country then actually delivers that pledge is a coin flip weighted by the compliance rate slider — a pledge on paper (Paris-style, non-binding) does not automatically become a real reduction.
pledge_i = ambition · resolve_i
emissions_i(t+1) = emissions_i(t) · (1 − pledge_i) if complies (prob = compliance)
= emissions_i(t) · (1 + 0.02) if defects
ΔT ∝ Σ emissions_i(t) · dt (cumulative, never reverses)
- Global ambition — how deep the average pledged cut is each round; low values mimic weak, non-binding targets, high values mimic a strong ratchet mechanism.
- Compliance rate — the probability any given country actually follows through, distinguishing a legally binding treaty (Kyoto-style, high enforcement) from a voluntary pledge-and-review system (Paris-style) with no real penalty for missing it.
- Negotiating countries — the number of parties at the table; more parties make free-riding easier to spot but harder to coordinate.
- Pillar colour: green = emissions falling and near its pledge, yellow = partial progress, red = emissions still rising (defected or never pledged deeply). CO₂ puffs visibly rise from red pillars into the atmosphere shell, which tints from blue toward amber as the temperature anomaly climbs — because cumulative emissions keep warming even after a country turns green.
Real-world relevance: the 1992 UN Framework Convention on Climate Change set the goal, the 1997 Kyoto Protocol tried binding targets with weak enforcement, and the 2015 Paris Agreement replaced binding targets with voluntary NDCs reviewed and "ratcheted up" every five years — this sim's ambition/compliance split is exactly that trade-off between what gets promised and what gets delivered.