The REgional Carbon Cycle Assessment and Processes (RECCAP) is an international effort to establish the mean carbon balance and change over the period 1990–2009 for all subcontinents and ocean basins. It is based on comparing and reconciling multiple bottom-up estimates, which include observations and model outputs, with the results of regional top-down atmospheric CO₂ inversions (and CH₄ and N₂O when possible).

This special issue presents the final synthesis papers for 14 RECCAP regional carbon budgets, 10 terrestrial regions (Africa, Arctic tundra, Australia, Europe, Russia, East Asia, South Asia, Southeast Asia, Central and South America, and North America) and 4 ocean regions (Atlantic and Arctic, Indian, Pacific, and Southern Ocean). In addition, 8 global syntheses support the regional budgets and their integration into the global picture.

RECCAP is an activity of the Global Carbon Project (http://www.globalcarbonproject.org/reccap), with two major sponsors: EU COCOS (Coordination Action on Carbon Observation Systems) and the US Carbon Cycle Science Program.