Climate Change, Climate Modes, and Climate Impacts

Variability of the atmospheric and oceanic circulations in the earth system gives rise to an array of naturally occurring dynamical modes. Instead of being spatially independent or spatially uniform, climate variability in different parts of the globe is orchestrated by one or a combination of several climate modes, and global changes take place with a distinctive spatial pattern resembling that of the modes-related climate anomalies. Climate impact on the dynamics of terrestrial and marine biosphere also demonstrates clear signals for the mode effects. In this review, we view modes as an important attribute of climate variability, changes, and impact and emphasize the emerging concept that future climate changes may be manifest as changes in the leading modes of the climate system. The focus of this review is on three of the leading modes: the North Atlantic Oscillation, the El Niño-Southern Oscillation, and the Pacific Decadal Oscillation.