Tropical Surprises

Abstract
Knowledge of decadal fluctuations in Earth9s climate is important for understanding how carbon dioxide emissions may change Earth9s climate. In his Perspective, Hartmann highlights the reports by Wielicki et al. and Chen et al., who have observed changes in the tropical energy budget over the 1990s. Changes in circulation and cloud patterns appear to drive this change, but the underlying cause is unknown. The reports highlight our limited knowledge of decadal fluctuations in climate.