Welcome to another edition of “What’s the Deal?” the blog that usually stays hydrated in some form or another.
In this week’s post, we’ll discuss the ongoing 4 year drought that has severely affected the western United States and what the short term and long term implications of the drought are.
We’ll also look into the discussions about why the drought is occurring and what may happen in the future in the region along with the implications of a warmer world on this region and others like it.
The Current: “Unprecedented 21st Century Drought Risk”
On Wednesday April 1, California Governor Jerry Brown announced an executive order imposing strict water usage limits on Californians, a 25 percent reduction on the state’s 400 local water supply agencies, with some cities facing a 35% reduction.
Brown appropriately made the announcement while standing on what usually had been several feet of snow pack, but with the extreme drought conditions was bare grass and dirt:
“The idea of your nice little green lawn getting watered every day, those days are past.” – Governor Jerry Brown
The executive order controversially does not pertain to owners of large farms, easily the biggest users of water in California, but farmers will have to issue comprehensive reports on water usage. Imposing fines on overuse of water by individuals and businesses will be a difficult task and perhaps a widespread one. Officials are hopeful Californians will voluntarily curb their usage, but a similar voluntary effort in the past ran dry quickly.
Was Brown’s executive order necessary? What kind of water issues is the state and the West facing?
With 178 gallons of water being used per person / day, the usage problem in CA seems to be easily visible.
The bigger problem simply is the lack of precipitation in a long term drought that is affecting a population area of over 52 million people.
Consistently drier and warmer weather for the past 3-plus years in much of the West and Southwest U.S. has led to significant decreases in lake levels, river flows, mountain snow pack, underground aquifers, and more.
Over the past 3 years, 60% of Western states have seen at least abnormally dry conditions with 20% of the West being in extreme to exceptional drought. The following charts and graphs below show precipitation levels, mountain snow pack and moisture percentiles.
Figure 1: Standardized Precipitation -Evapotranspiration Index – basically, precipitation minus water loss to temp/dryness for Februaries in Nevada.
As you can see, the past 3 years is all in the deep red – far lower than any point in the last century.
Figure 2: % of Normal Precipitation.
Much of California here is well below 70% of normal precipitation averages.
Figure 3: Mountain Snowpack, March 2015.
While some of the Rocky Mountains in Montana, Wyoming, and Colorado are experiencing normal – above average snow pack conditions, the Cascades and Sierra Nevadas are facing extreme snowpack shortages and reduced levels.
This is a huge issue because annual snowfall and snowpack in the mountains provides much of the ground water and surface water for the large population residing in California and Nevada.
Figure 4: Total Current Moisture Percentile 2015
Once again the values here show extreme conditions in California that are likely to increase in severity as warmer months arrive and the decreased snowpack does not accommodate the groundwater and surface water need.
The Scope and Impact of the Problem
The figures don’t just show drought conditions in the West, but show extreme conditions that pose a severe threat to the water availability for citizens of the region.
With lack of water comes other serious conditions such as huge sink holes, building collapses, large economic impacts on different industries (such as ski resorts), and most importantly the impact on the agrarian sector. California’s Central Valley provides an enormous amount of food; nearly half of the nation’s fruit and vegetables come from California and much more is exported overseas.
With farmers being exempt from the water restrictions as of now, crop output should be on par as previous years and consumers shouldn’t see too big of a hit in the produce department at the store, but at a big cost. Large farms are pumping huge amounts of groundwater from wells that are drilled – depleting a resource that was always sensitive even before the drought. The withdrawals are far exceeding the replenishment and are starting to lead to serious problems. In some places the water table has dropped by 50 feet in the past few years. Permanent damage to the underground water storage capabilities (aquifer storage in sand and clay) may be the biggest issue in addition to sink holes, damages to smaller farms, and damage to roads and bridges.
So we’ve outlined the problem in detail (more detail than perhaps you wished), now let’s examine the historical record and reasons behind the exceptional drought.
“Mother Nature didn’t intend for 40 million people to live here”
The historical data on droughts in the U.S. since 1900 suggest that Western states will certainly see higher levels of precipitation at some point and that the drought will eventually break. But the historical data also shows something else: this current drought is unprecedented in its severity and longevity.
What about in the future? Will this be a one time drought that westerners can adjust to like other situations? Or is something more sinister at work?
The projections for the future climate out West are relatively bleak, primarily as a result of global warming from higher greenhouse gas levels. Using historical data gleaned from tree ring samples to create climate models from the past 2000 years, researchers applied 17 different climate models which used soil moisture measurements and the Palmer index for net precipitation in conjunction with 2 different CO2 emissions projections.
The tree ring data gives researchers an idea of growing conditions for the tree during that particular year. Larger / fatter ring = better growing year with higher precipitation levels. Skinny ring = drier year with less precipitation. This is similar to the way scientists gain climate information from ice core rings: thicker ring: better snow levels/lower temperatures, skinny ring: warmer conditions, less snow.
The results from the study were the same: Higher risk of drought with higher global temperatures.
“The results … are extremely unfavorable for the continuation of agricultural and water resource management as they are currently practiced in the Great Plains and southwestern United States,” David Stahle
The higher risk of drought correlates with global warming as higher temperatures lead to a drying out across the West and significantly reduce snowpack in the mountains. This, according to climate models, could lead to droughts that last 2 – 3 decades – making current agricultural and populations in the West unsustainable. Notable from the research is the 2nd climate scenario in which human populations are able to curb emissions. In this second scenario, drought risk is still present, but far less severe.
So what we can say from this study and others like it are that the drought is severe now, but the worst is yet to come.
Conclusion: Much ado about nothing?
One striking example of the lack of water in the West that is easily seen is the case of the Colorado River and Rio Grande and how they have been reduced to a trickle because of overuse and dry conditions. It is likely that these rivers and the water sources they create (Lake Mead, etc…) will no longer be adequate for even supplementing water supplies – a huge deal for the large population centers that depend on them for drinking water and for agriculture which depends on them for crop production.
So is this drought in the U.S. a result of climate change?
It is very difficult to pinpoint a weather related disaster such as a drought or hurricane as a result of a long term climactic event such as human induced climate change. This is because climate change is a phenomenon that occurs over a longer period of time while a single drought is a short term weather related event. So we cannot say for sure that this drought is the direct result of climate change.
We can say, however, that the chances of drought have increased given the conditions yielded by climate change: drier weather patterns from an increase in global temps. But is only asking “Did climate change cause this drought” the real question to ask?
Perhaps another question to ask is should people continue their business as usual in areas experiencing extreme drought? and what are the effects for everyone else?
If states in the West are going through drier, warmer weather on a more consistent basis, then water will be a limited resource for everyone. Let’s take a look at what people will need to adjust to:
As Governor Brown quipped, no more nice little green lawns for everyone, and the 25% reduction will hit many everyday things for individuals and businesses. The goals for water reduction may be easier to hit for the cities as technology, water reclamation, and even desalination plants (a controversial project). What will be most difficult is for agriculture. The biggest users of water is from agriculture and there will need to be an adjustment to a situation where even groundwater is no longer a backup option for water.
As discussed earlier, with so much of our food being grown in the area and the significant stress put on aquifers by pumping, the ability to retain precipitation when it does fall will have significantly diminished, leaving less groundwater to pump. When that does happen, the ability to be a huge source of food for the U.S. and the world will be unsustainable.
In a snapshot, the big picture of a lack of water in the West brings us back to those rivers.
The rivers are a good starting point because it is rivers that are a determinant of water for a majority of the world’s population. Whether it is the Sacramento River, the Colorado River, the Rio Grande, or the Indus, the Bramaputra, or the Yangtze, rivers are the lifeblood for so much of humanity, that significant changes in water levels could be a matter of life or death.
The facts on clean water availability for the world’s population is well known, but less known is availability of water at all for people and agriculture in dry or arid regions. The huge populations of South Asia dependent on sufficient water flow on tributaries from the Himalayan Mountains are in a tenuous situation. Without sufficient rainfall or mountain/glacial snowmelt farmers and citizens alike could be without a significant source of water.
This tenuous situation is compounded by climate change as glaciers are melting in the Himalayas leaving less long term water storage in the form of ice. In this situation, access to water could be severely limited for some of the world’s largest population centers.
The impact on the U.S. will certainly be significant and the adaptations that will be required will be interesting to observe as they develop. Most importantly, perhaps they can provide a model for other parts of the world to follow if climate change leaves water resources dry.
Until the next water reduction mandate,
Your Faithful Historian,
Eric G. Prileson
Sources and Further Reads:
The Earth Institute at Columbia University. “Warming pushes Western U.S. toward driest period in 1,000 years: Unprecedented risk of drought in 21st century.” ScienceDaily. ScienceDaily, 12 February 2015.