New biotic pump paper: How forests manage aerial rivers | Stormy ...
The biotic pump concept clarifies why the moist aerial rivers flow readily from ocean to land when the latter gives home to a large forest — and why they are reluctant to do so when the forest is absent. The dormant winter forest loses this war to the ocean, such that precipitation over the Atlantic Ocean in winter, despite the oceanic evaporation is minimal, rises threefold compared to summer months. While it is increasingly common to blame global change for any regional water cycle disruption, the biotic pump evidence suggests that the burden of responsibility rather rests with the regional land use practices. Properties of the aerial rivers that ensure the “run-in” of water vapor inland to compensate for the gravitational “run-off” of liquid water from land to the ocean are of direct relevance for the regional water availability. Compared to our previous studies , in the new paper we used a global (rather than land only) precipitation database that allows one to compare precipitation patterns on land to those over the adjacent ocean. A conflict ( rarely appreciated or discussed ) exists between the modern commercial value of a forest and the forest’s ability to regulate the regional water cycle and to be self-sustainable: these parameters cannot be maximized simultaneously. Apart from the tropical rainforests, we analyzed precipitation distribution across world’s longest (>7,000 km) forest belt, the Eurasian boreal forest. The data describe how the active summer forest wins the water “tug-of-war” with the Atlantic Ocean. Indeed, in summer the forest steals most moisture inland and depletes the oceanic precipitation. Water cycle on land owes itself to the atmospheric moisture transport from the ocean. Analyzed for comparison, the unforested Australia is unable to draw moisture far inland in either wet or dry season, i. e. , irrespective of moisture availability over the neighboring ocean. On large areas on both sides of the Atlantic Ocean, temperate and boreal forests are intensely harvested for timber and biofuel. We extended our previous approach to analyze seasonal (rather than annual only) changes in the spatial precipitation patterns in world’s major forest regions.
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