CLIMATE-CHANGE RELATED DROUGHTS MIGHT DEFEAT SUSTAINABILITY EFFORTS (Invited Presentation)

A 2008 article identified “strategic surprises” as inevitable, “game-changing” events that challenge conventional wisdom. The strategic surprise with respect to groundwater is that in the face of climate-change related drought, humanity cannot rework the hydrologic cycle to provide for sustainability. In history, there are examples of seemingly innovative societies unable to conquer drought – the Garamantes of North Africa, the Mayans of Central America, and the Puebloan societies of southwestern North America. Another constraining factor is that we are past peak water. According to Gleick’s definitions, peak water involves the human appropriation of “ecological” and surface waters, and the draining of aquifers. Hydrogeologists have always regarded the vast quantities of stored groundwater as humanity’s hedge against the uncertainties of surface waters. Ironically, as that treasure has been squandered here in America, we have embraced the importation of surface water to provide sustainability. However, surface water in the western US is commonly allocated/over-allocated and going away. There are useful lessons from the groundwater story in the San Joaquin Valley. Timely action in the 1960s seemingly reversed the depletion of groundwater and halted widespread subsidence. The wild card for two decades has been drought’s impact on the availability of surface water. Mann and Gleick writing in PNAS in 2015 pointed out how the character of recent droughts in California has changed to reflect both an absence of water and drying magnified by increasing temperatures. The renewed drought (2019-2021) is also “very dry and very hot” with large reductions in imported surface water for irrigation available to the San Joaquin. Expectations, however, reflect business-as-usual thinking that the droughts will wane and that schemes to capture excess surface water flows and a 10% reduction in irrigated acres will rebalance groundwater utilization. However, tracking of 36 indicators of climate change paints a picture of marked environmental and ecological transitions reflecting drier and hotter conditions. In the absence of runoff, a sustainable groundwater system has minimal capacity to support irrigated agriculture.