Tyler,
I am in Oklahoma. Here climate change means flood or drought, little else. Our state is probably best known for being dead center of the "dust bowl" of the 1930s. We are also right in the middle of "tornado alley", right behind our neighbor Kansas in frequency and severity of supercell storms and tornados. Safe to say that "Sooners" as we are called are quite accustomed to severe weather events. The question for Oklahoma is how global warming and climate change effects our already extreme weather and maybe just as importantly our groundwater supplies.
The science predicts that climate change trends for us means rain-free periods will lengthen, but individual rainfall events will become more intense.[1] We know Oklahoma is already subject to extremes of weather, but the trends say it is getting worse, not better.[2][3]
According to the National Climate Assessment the last drought that just ended last year was both hotter and drier for Oklahoma than a similar period of the 1930s Dust Bowl. In 2012 we set the all time record for number of days over 100 degrees in a single year.[4] And what about floods? May 2015 set the record in recorded history for the wettest month in Oklahoma. Most of this rainfall occurring as part of supercell storms producing damaging EF5 tornados, hail and flooding.[5] So it seems our already extreme weather is getting even more extreme.
Sounds bad right? Well it might even be worse than it seems. To understand why we need to look at the water cycle and aquifer stocks and flows. Our aquifer basins are in a constant state of flux as inflow from groundwater seepage can fill them and we pump out water for human and agricultural uses. The largest aquifer in Oklahoma, the Ogallala is down 150 feet from historic levels. Some of the shallower aquifers are up a small amount, being somewhat replenished by these heavy rainfall events. However, taking all the aquifers into consideration the net flux overall is down. More is being pumped from the wells than is being replaced by groundwater seepage.
Since both usage (outflow) and climate (inflow) are controlling factors to aquifer levels (stocks), let's look at how climate change is affecting these fluxes, which in turn affects the basin total stocks of water.
So how does climate change to global warming affect the water cycle of Oklahoma? Droughts are pretty straight forward. Less water seepage into the aquifers and more farmers pumping larger amounts out of the ground to irrigate fields. Maybe less known is the effect severe storms has. Even though a lot of water falls as rain, it is less effective than gradual rainfall over a longer period of time. Less soaks into the ground and more runs off and creates floods. Also since this happens in a short time frame, before the water can soak far, the sun is back out causing evaporation.[1]
I believe this increased variability to extremes, hotter drier droughts and more severe storms, is primarily why overall our groundwater stocks are dropping. Less and less water is infiltrating to replenish our already overburdened aquifers. Climate change is already affecting us in Oklahoma in many ways, and trend is only getting worse.
I suspect most the earth has a similar story to tell. The effects of climate change different in each area, but already here, and ever so slowly increasing year by year. I investigated the impacts of my area, so that when I meet a person like that, I would be prepared to explain it in a way that gets their attention? Once I have their attention, I also mention what I personally am doing to mitigate it. (You guessed it, permaculture) They might think it is a good idea and try it too?
1) Dr. Ken Crawford and Gary McManus, STATEMENT ON CLIMATE CHANGE AND ITS IMPLICATIONS FOR OKLAHOMA, Oklahoma Climatological Survey,
https://www.ok.gov/conservation/documents/climate-statement-ocs.pdf
2) Climate change in Oklahoma,
http://www.southernclimate.org/documents/climatechange_oklahoma.pdf
3) JOE WERTZ, Drier, Hotter, More Extreme Weather: How Climate Change is Already Affecting Oklahoma,
https://stateimpact.npr.org/oklahoma/2014/05/08/drier-hotter-more-extreme-weather-how-climate-change-is-already-affecting-oklahoma/
4) National Climate Assessment, Great Plains, U.S. Global Change Research Program 2014,
http://nca2014.globalchange.gov/report/regions/great-plains
5) Chris Dolce, Nick Wiltgen, Jonathan Erdman, Texas and Oklahoma Set All-Time Record Wet Month; Other May Rain Records Shattered in Arkansas, Nebraska, The Weather Channel Jun 1 2015,
https://weather.com/forecast/regional/news/plains-rain-flood-threat-wettest-may-ranking