Thursday, November 30, 2017

Vanishing Lakes

An article in the New York Times this week highlighted the gradual disappearance of the Great Salt Lake.  While one might suspect global warming is the cause, the article points out that the diversion of inflow for irrigation and other human activities is the primary culprit.

No doubt, climate change has long played a role in both the formation and disappearance of lakes.  During the cold, wet climate of the Pleistocene, massive lakes covered most of the Great Basin (see Lake Bonneville and Lake Lahontan) while glaciers scoured out lake basins across the northern half of North America (the Great Lakes and Finger Lakes offer prime examples).  As the climate warmed during the Holocene (now augmented by human activity), the Great Basin lakes shriveled in size, waxing and waning in response to the mountain snowpack and human consumption; how future global warming will affect the snowpack remains uncertain but the pressure of a burgeoning human population will clearly be a problem.

Lakes have long been transient features of Earth's landscape, forming in the wake of floods, landslides, glacial erosion, volcanism and tectonic rifting.  Their disappearance may result from diminished inflow, increased evaporation, catastrophic drainage (e.g. from earthquakes) or the gradual deposition of sediments that fill in their basin; the later is a common problem in man-made lakes and reservoirs where dredging is eventually required.