Abstract
The apparent accumulation of carbon on land necessary to balance the global carbon budget has perplexed scientists since the first carbon budgets were constructed more than 40 years ago. The magnitude of the sink over the decade 2006–2015 averaged 3.1 ± 0.9 PgC/year, but neither the factors causing it nor its location are known. Here, based on results from a recent analysis by Baccini et al. ( ), we estimate that about a third (1.0 PgC/year) of the residual sink is in the tropics, and about two‐thirds is outside the tropics (2.1 PgC/year).