People quickly forget when it comes to ‘extreme weather events’. This was one of the main conclusions of the 2014 Great Plains Symposium in Lincoln, Nebraska in early April 2014. Forgetting about much more severe droughts of both a nearer and a more distant past, many politicians were quick to label the 2012-13 drought in the farming belt of US Mid-West as one of the worst in history and to blame climate change for it.
But as research presented at the symposium showed, drought is a normal part of the climate in the Great Plains. And in the past these droughts were much more severe than the most recent one; in today’s information age it should not be overly difficult to find information on an at-least-as severe drought in the region in the 1950s, and the even longer dry spell of the 1930s, known as the ‘Dust Bowl’ when more than 5,000 Americans died.
Looking even further back to ‘medieval mega-droughts’ (at research by Professor Sherilyn Fritz of the University of Nebraska-Lincoln), the Dust Bowl period was only slightly above the average degree of dryness of the last 2,000 years (you have to read the chart from right to left; the zero-point on the horizontal axis is for the year 1950).
800 years ago, during the Medieval warm period, significant parts of the Great Plains were a sand desert with wandering high dunes (100 metres and more) driven by the winds. (Paul Hanson, Associate Director of the School of natural Resources at University of Nebraska-Lincoln).
Plain dunes were also active during mega-droughts 2,500 years and 4,000 years ago.
With facts like these in mind, Martin Hoerling, research meteorologist, and his team of scientists in the US government’s National Oceanic and Atmospheric Administration (NOAA) took an in-depth-look at the last drought in a study published in 2013 “An Interpretation of the Origins of the 2012 Central Great Plains Drought”. They concluded that “neither ocean states nor human-induced climate change appeared to play significant roles in causing severe rainfall deficits over the major corn producing regions of central Great Plains” but “resulted mostly from natural variations in weather”. Since the study was contradicting earlier comments from very high-level politicians, the result of the NOAA study were quickly criticised as “needlessly confusing”.
So, what was special about the 2012 drought in the Great Plains? In a post on my personal blog from August 2012 I formulated the hypothesis that the recent drought had a more severe impact because of the massive overuse of fossil groundwater from the Ogallala aquifer, originally underlying some 35% of the Great Plains. Using its water for irrigation and municipal supply during decades of above-average humidity in the region (e.g., compared to the periods of prolonged drought several hundred years ago) has meanwhile reduced Ogallala freshwater availability by some 50%.
Interestingly enough, land values reflect access to Ogallala water; the premium (one form of measuring natural capital) was at some USD 30 billion in the early seventies; by 2002, after extraction of some 250 km3 of water, the premium had decreased to USD 12 billion. This values one cubic metre of extracted water at some US Cents 5-10.
Main speakers at the Nebraska symposium stressed one learning from history: there can be little doubt that decade-long droughts will happen again in the Great Plains, independently of human influence on climate.
Two conclusions from this, for further discussion here on LinkedIn:
- Once natural cycles bring back truly severe drought similar to the one during the Medieval warm period, water extracted from the underground aquifers during times of relative abundance of surface water will be painfully lacking once times get really tough again. The value of water in the Ogallala – if some is left – will be much higher than the few cents it is apparently worth today. We will have to create awareness for this important fact; it reflects something that goes far beyond financials.
- This might then lead people of the Great Plains to address water management (supply, use of ever scarcer water for what is really needed, efficiency of use) in a much more strategic and comprehensive manner. We must foster the understanding that addressing climate change alone – as important as it is in its own right – will not solve the huge water risk for a region that has become an important bread basket for the world, i.e. affecting also the social and economic pillar of sustainability. Strict and long-term oriented water management in this and many regions is no longer something “nice-to-have”.
Read the original article: Drought and groundwater in the Great Plains of… – LinkedIn
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