Abstract
Atmospheric circulation is a fundamental component of Earth’s climate system, transporting energy poleward to partially offset the latitudinal imbalance in insolation. Changes in the latitudinal distribution of insolation thus force variations in atmospheric circulation, in turn altering regional hydroclimates. Here we demonstrate that regional hydroclimates controlled by the Northern Hemisphere mid-latitude storm tracks and the African and South American Monsoons changed synchronously during the last 10 kyrs. We argue that these regional hydroclimate variations are connected and reflect the adjustment of the atmospheric poleward energy transport to the evolving differential heating of the Northern and Southern Hemispheres. These results indicate that changes in latitudinal insolation gradients and associated variations in latitudinal temperature gradients exert important control on atmospheric circulation and regional hydroclimates. Since the current episode of global warming strongly affects latitudinal temperature gradients through Arctic amplification, our results can inform projections of likely inter-hemispheric precipitation changes in the future.
Highlights
Atmospheric circulation is a fundamental component of Earth’s climate system, transporting energy poleward to partially offset the latitudinal imbalance in insolation
Because of the relatively constant Atlantic meridional overturning circulation during the Holocene[28], the observed inter-hemispheric precipitation changes can only reasonably be explained by insolation variations
The Northern Hemisphere mid-latitude precipitation change since 10 kyr BP is controlled by the strength of midlatitude storm tracks, which are in turn forced by the latitudinal temperature gradient between the low-latitudes and the highlatitudes[3]
Summary
Atmospheric circulation is a fundamental component of Earth’s climate system, transporting energy poleward to partially offset the latitudinal imbalance in insolation. We demonstrate that regional hydroclimates controlled by the Northern Hemisphere mid-latitude storm tracks and the African and South American Monsoons changed synchronously during the last 10 kyrs We argue that these regional hydroclimate variations are connected and reflect the adjustment of the atmospheric poleward energy transport to the evolving differential heating of the Northern and Southern Hemispheres. Since latitudinal temperature gradients are currently decreasing due to Arctic warming[16], it is important to test the hypothesis that patterns of tropical and extratropical precipitation are linked consistently to latitudinal temperature gradients during the Holocene If this hypothesis is proven to be robust, it can contribute to the development of an improved energy-budget framework for tropical atmospheric circulation and regional monsoon systems[17]. We develop a conceptual framework to explain the synchroneity of these interhemispheric precipitation responses by variations in latitudinal insolation gradients, and in turn latitudinal temperature gradients, that changed substantially during the Holocene[3,4,18]
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