NDC Ratchet Mechanism Simulator

The Paris Agreement doesn't set national emissions targets from above — it runs on a repeating 5-year loop of self-set pledges (Nationally Determined Contributions) that, by treaty design, can only ratchet upward in ambition, followed by a Global Stocktake that measures the gap between what's pledged and what a 1.5°C carbon budget actually requires. This simulator renders twelve illustrative negotiating blocs as a live 3D emissions field: run each stocktake cycle to watch ambition ratchet, emissions respond (net of an implementation gap and business-as-usual growth), and projected warming update through a simplified cumulative-emissions climate response — the same mechanism that makes the "ambition gap" the number climate diplomats watch most closely.