by Matt Owens December 26, 2012
After the Arctic sea ice surprise of 2012, this question isn't so ridiculous: could we be seeing the initial stages of a major ecological/weather shift over North America? One where the Southwest and Midwest regions turn so arid that farming, ranching, and even human habitation is no longer practical?
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The causes of the drought are clear by looking at the temperature and precipitation trends. Wichita Kansas, right in the middle of the afflicted area:
Both charts depict a 5 year period ending December 20th, 2012. The top chart shows maximum and minimum daily temperature averages, on a 30 day moving average basis (in other words, each data point on the line is the past 30 days averaged). The bottom chart is precipitation on a 90 day moving average basis.
Temperature has clearly been rising in the summers especially. More erratic, but still noticeable warming has been seen during the winters. The first 12 month period on the chart (Dec. 20th 2007 - Dec. 20th 2008) is almost exactly the climatological average for Wichita (using 1981 to 2010 as the basis), so the trend over the past years is clearly a big one, with the 30 day moving average summer high nearly 7.5°C higher by 2011 and continuing into 2012. The rise of daily low temperatures has also been trending upwards, but less so, at around 2.5°C.
Precipitation stands out for both its steady decline year-over-year, and for the breakup of the typical seasonal patterns in 2011 and continuing through 2012. Typically (again, using 1981 to 2010 as baseline) precipitation drops to below one mm/day average in January and reaches a peak of over 4 mm/day in summer; so the starting point of the past 5 year trend is actually above average for rainfall, but drops well below in early 2011.
The difference between summer and winter has also been leveled. The extra winter water has not been put to good use however, because there has been less snow cover, and so evaporation has been higher.
And of course, higher temperatures typically lead to higher evaporation. Soil moisture, and therefore drought, is governed by a disarmingly simple equation:
(Precipitation) - (Runoff) - (Evapotranspiration) = (Soil Moisture)
Precipitation is easy to measure. Runoff is not as easy, but still feasible if enough river/stream gauges are in place and working. Evapotranspiration however is a combination of evaporation from the soil itself and transpiration (biological water vapor release) from plants, and is very challenging to estimate correctly (direct measurements for large areas are not practical at this time). Evapotranspiration is governed by the plant ecology and dynamic response to local dynamic conditions.
As complex as it is, evapotranspiration (ET) follows some basic rules of thumb: when temperatures rise, plants try to grow more. Thus, higher temperature means that the soil naturally looses more water and that the plants also release much more water vapor with increased growth rates. Plant communities are complex however, and shifting dominance of plant species within the community can change ET rates under given conditions. Plus, each plant species, and in some cases, subspecies, has a different rate of transpiration "programed into it."
And the rate of transpiration varies depending on the plant's growth stage too, so there are several lags (and thus feedbacks/interferences) built into the ET-soil system.
There are an estimated 300,000+ species of plants, and modeling the transpiration rate of just one species under just a few conditions takes a good deal of work and time.
Difficulties aside, we can see that drought is here in the U.S., and could be getting much worse in 2013.
In Washington D.C. we have seen similar trends as seen in the drought afflicted areas, but conditions have yet to breach critical levels:
The trends in the D.C. area, like those in Kansas, could be on the verge of a course change, back to normal conditions. But we know that global warming means that temperature trends like those of the past five years will continue, and that ultimately, there will be no return to normal. So it is more likely than not, that the last 5 year temperature trend will continue its march upwards.
The D.C. area temperature and precipitation is moderated by the ocean however. Temperatures are therefore expected to rise slower than for areas further inland. But they are rising nonetheless. And the drought is in fact creeping into Virginia from the south:
If the areas under D4 drought stay at those levels for long, they will only be able to produce decent crops with the help of irrigation. Without it, yield will be extremely low, to the point that harvesting the crops may not even be worth the effort. Under such conditions, whatever growth there is for the crops can be tilled back into the soil or cut and used for hay.
To give some perspective on today's situation, here is NOAA's computed Palmer Drought Index (PDI) map for the U.S.:
The PDI is a commonly used drought index, and shows much of the same trend as the U.S. drought monitor. In a 2010 study by the National Center for Atmospheric Research (NCAR), drought resulting from global warming was forecast to become worse than 2012'a extreme. As summarized by Joe Romm at ClimateProgress.org, the drought situation would be "brutal." Romm goes on to say that "feeding some 9 billion people by mid-century in the face of a rapidly worsening climate may well be the greatest challenge the human race has ever faced."
Here is a future PDI projection map from the NCAR study:
West of the Mississippi, nearly all of the U.S. in this projection is under drought conditions that would be as bad or much worse than they have been in 2012. And this map depicts the average conditions for a ten year period, so some years would be worse still. At these levels of drought, farming without irrigation would likely not even happen west of the Mississippi.
Also, note the very serious drought for Turkey and into the Romanian-Balkan region. 2012 has been, and continues to be very bad for that region. But the conditions projected on this map would be so bad, that a mass emigration could ensue. Ground water could be used to replace dried up reservoirs for many areas of the region - but only for a short while and only in select areas with non-polluted water sources.
The demand put on the aquifers would quickly outstrip supply at such extreme levels of drought. And power supplies would also suffer (and they already are today) as hydroelectric plants would cease working. In fact, fossil fuel power plants need water supplies for cooling, although they can be upgraded to use water more efficiently.
And, the projection from the NCAR study for further down the climate road is even worse:
Here, the U.S. would see basically desert conditions emerge west of the Mississippi to the Rockies. Georgia and into Florida and points west would become arid - right on the edge, or possibly tipping into desert. There would still be an area of the Ohio Valley where irrigated farming might stand a decent chance of maintaining high yields - so long as groundwater supplies lasted.
As an alternate to groundwater would be the Great Lakes, but the levels of those bodies have already been dropping seriously in 2012. Almost no snow and ice cover has formed on the Great Lakes for the past several years, which is very unusual and also leads to high evaporation from the warm water into the cold winter air. As global warming continues, ice forming on any of the Great Lakes over winter - if it actually ever happens again - could become the exception.
So the multi-decade outlook is very bad, but there are still some uncertainties. Those uncertainties however, are not equally distributed. And they mostly involve other very bad things happening which might offset the drought conditions. Those things generally involve a destabilization of the climate, meaning higher weather volatility, i.e. not a good situation for growing crops.
In the near-term, the outlook is also not good:
The U.S. drought is forecast to likely continue and/or worsen west of the Mississippi to the Rockies from now until at least March, 2013. This forecast has its own uncertainties built into it, and with weather patterns breaking rules regularly these days, there is perhaps some room for optimism if you're livelihood depends on a good growing season in the effected area. Ultimately of course, everyone suffers when crops fail - food prices and energy prices rise. A correlation between food price spikes and increases in civil unrest/revolution has also been observed. Perhaps the most famous instance was the French Revolution, but the Arab Spring events also occurred after spikes in food prices.
If the drought conditions do worsen for the U.S., then the soil will become progressively drier, and require much more water before it returns to a condition suitable for growing crops again. And forests and uncultivated areas also suffer too. Trees and plant communities will start to die-off in massive areas if the drought continues for too long. How long exactly has yet to be fully quantified, and researchers are just now starting to tackle that question.
However, forests in the Southwest have already seen large die-offs that are approaching the "mass die-off" level.
No surveys of tree die-off events have yet been completed for the U.S. as far as I know. So we can't say how exceptional the observed events are. But, knowing that the droughts, rising temperatures, and changing weather patterns are all stressing the plants, we can deduce that this is very likely the beginning of an exponential trend in plant die-offs.
Trees are especially vulnerable because they take many years or decades to grow and thus when local conditions move outside (and stay outside) the tree's tolerance limits, it becomes just a matter of time until they die.
In the Amazon rain forest, there have been a number of recent droughts, and now researchers are saying that they've uncovered a significant increase in tree mortality in the drought-effected region (an area twice the size of California). This comes on the heels of another study this month that shows the world's oldest trees are dying-0ff at unnaturally high rates.
If this does turn out to be the beginning of a global plant die-off, it could mean a reduction in forested areas and an increase in desert areas. Sudden die-offs of even just one species in a given ecosystem can sometimes lead to major shifts for the whole system, so effects would be different for each area depending on which plants go first. And not all plants would die. In fact, cosmopolitan species (ones who have global or nearly-global distribution) would stand to do the best. Generally these are fast-growing plants, often thought of as weeds. They can be found colonizing disrupted land, i.e. a mound of excavated dirt at a construction site. So the diversity of plants makes the picture complex again.
What I can say is that in general, global ecosystems could be shifted to more semi-arid types of plant communities. Scrub-land vegetation, in other words. Scraggly bushes, grasses, and a few stunted trees.
If climate change is stopped or slowed to the point that weather and temperature stays fairly constant on regional scales, then the trend towards scrub-land dominance could reverse back to something else. But, if a stability is restored with carbon dioxide levels still elevated, then what that "something else" might be is an open question.
This could be the start of a massive change to the plant communities around the world, with major die-offs possibly already in the initial stages where climate-change-stress weakens them to the point that future perturbations will tip the scales. For agriculture in the U.S., drought conditions are the primary focus, and are likely to worsen in 2013. The best of our knowledge indicates that even if drought conditions do alleviate in 2013 or later, they will return with a vengeance. For those living in the Midwest, Southwest, and Southeast of the U.S., as well as those living in the Balkans, Western Turkey, and Southern Europe, a serious consideration should be undertaken about the possibility of loosing reliable water supplies. Many people may suffer serious financial losses from the radiating impacts of serious, prolonged, and worsening drought. Many others may be forced to emigrate from their states or countries.
Other significant impacts could be felt as early as 2013 if the drought worsens. Civil unrest and civil war could overtake several more countries as a result of sudden sharp rises of food prices. Global economic systems could suffer declines too as a result of drought; when the crops fail, the result is an actual destruction of wealth and assets in the form of food which radiates out to the economy - people forced to pay more for food (and increasingly bio-fuel) have less to spend on everything else and thus the value of other assets falls while the costs of production remain the same or rise. This reduces profit margins and inhibits wage increases, hiring, promotions, and new business start-ups.
In other parts of the world, climate change is expected to increase precipitation, and thus far, that trend has been corroborated. Unfortunately, those areas are mostly open ocean, tundra, or nearly tundra.
Contrary to some superficial presumptions, exemplified by the pompous Exxon-Mobil CEO Rex Tillerson, industrial farming will not suddenly become feasible in northern Canada or northern Russia. At some point, when climate stabilizes, farming might be better at those extreme latitudes than it is today, but the sun will still only shine so much and the soil there still has a lot to be desired.
And what's more, climate change is projected to increase the rate of rainfall during increasingly intense storms. This effect has already been observed over the UK. Residents of the D.C. area are already familiar with evening thunderstorms that bring brief but intense downpours. Driving on the beltway in such a storm is quite the adventure! But the derecho of 2012 was in my opinion easily 10 times worse than typical storms - and it stretched across several states and swept all the way from the Midwest to the Atlantic coast. If such intense derecho storms become commonplace, we will all be scrambling to "harden our assets." Such intense and brief rainfall durations contribute large amounts to the record of precipitation, but the runoff is so high that the soil actually doesn't benefit as much as it would for less intense precipitation. Soil actually gets washed away instead. This pollutes the river and coastal waters with excessive nutrients and leads to algae explosions which contribute to dead-zone formation and fish/shellfish die-offs.
The picture isn't too pretty, but there it is. If there is any doubt in your mind that climate change is vastly under-estimated, vastly under-prepared for, and vastly under-studied by our current society, I would love to hear your reasoning.
That is, unless you're pompous like Rex Tillerson. Such people know nothing beyond superficial trivialities about the many complex fields involved, but nevertheless feel confident that they are somehow gifted with a deeper and truer knowledge of the subject just by virtue of the fact that they can construct complete sentences using key words and phrases. Or maybe I'm wrong about Mr. Tillerson - maybe he blows off his day job as CEO of Exxon-Mobil, one of the world's largest companies, and spends his time at the office secretly researching climate science. Maybe he's been doing this for years and actually secretly went back to college and got a secret degree in ecology or environmental science.
Or maybe I'm right, and Mr. Tillerson is an engineering major who graduated in 1975 from the University of Texas at a time when climate change was still a highly speculative affair among the general scientific community. And maybe he was hired by Exxon the same year he graduated from undergraduate school and has spent his entire career working there.
Maybe, Mr. Tillerson is like an extreme example of a lot of Americans - he has a vested financial interest in believing fossil fuels not potently toxic to our global ecosystem and climate. Americans have for many decades now been investing their money in oil stocks, bonds, and other equities. Indeed some of the biggest and most fantastic returns have come from a lucky purchase of bonds or stock of some no-name oil venture that struck a big-one. A real gusher. That was the old days, and now its mostly middle class aging baby-boomers who have stock in oil, gas, and utility companies. Such investments are seen as safe-places to store hard-earned money; because, after-all "there will always be a need for fuel, right?" So goes the reasoning anyway. And it's true, we want fuel. We need it. We have for ages. Since the time we first started using fire - which may have been one million years ago, or possibly longer. We have in fact, been a potent influence on climate and ecology for a long time now.
But now we know more. We now have uncovered hidden mechanics of nature and can see a glimpse of our future. We need to do something now, because this new view is just in time - maybe. There is no guarantee. If there is one thing I am certain of, it is that letting "things ride" is not the right choice when confronted with such a truth as climate change. The end for you and me is inevitable as mortal beings, but the way we live and die is hanging in the balance, and a hellish future is not anyone's idea of a good way to spend it. Even if the hell of climate change waits for 100 years, there could be ripple-effects that precede the worst. These will not just be from the climate, but also from the youngest people who have seen an ugly future of a seemingly pointless sentence for no known crime.
In some ways, I admit that I almost agree with the pompous Mr. Tillerson in the sole respect that we will try to adapt. Success is not guaranteed however. All things must come to an end. So with that in mind, the drought situation in the U.S. is put in a new light.
If conditions worsen, it could mean that drought estimations have been under-balled and climate change is harming global ecological stability much faster than expected. And then, there could be increased urgency to adopt solar and wind alternatives to fossil fuels. That is regardless of the true significance of the drought.
If conditions are relieved, then perhaps the worst possibility will unfold, which is that people forget and fossil fuel use continues without restraint until a global cataclysm cripples the global economy.