Problems have solutions; dilemmas have consequences! The reality of climate change can’t be avoided but the consequences for humans and other life forms can be made worse by our decisions. There is a difference between solving problems and living with consequences. Solving problems means we can try to fix what is wrong. Living with consequences means we must face the reality of our situation. The reality of climate change is already impacting the hydrologic cycle—increased precipitation, evapotranspiration, runoff, and river flow— but we can make our situation worse.
This year we are witnessing another Great Flood event unfolding along the Mississippi River and the cost of damage won’t be known for many months. Spring flooding along river basins is common as the snow melts and spring rain runs off frozen ground. Unfortunately this springs flooding came at a very bad time for Missouri and Iowa farmers forced to store much of their soybeans harvested last fall due to Trump’s tariffs and China’s decision not to buy US soybeans. Political decisions have made the consequences of a flood disaster even worse for Nebraska and Iowa farmers, many of whom say it will put them out of business.
There is an intersection between politics, economics, and climate change where the decisions in one area affect outcomes in others. Political decisions such as denying climate change, cutting taxes, or supporting the fossil fuel industry can make the consequences of climate change much worse. Economic growth is causing damage to the environment, loss of species diversity, and worsening of the human condition. Business-as-usual profit seeking at any cost is likely to make adaptation much harder than it needs to be for most of the world’s people.
The basic science of climate change is straightforward; as the atmosphere fills with greenhouse gases it becomes warmer. The heat in the atmosphere warms the oceans and melts ice. A warmer ocean evaporates more easily and a warmer atmosphere holds more moisture. A warmer arctic means ice melts more quickly. Scientists predict many changes to weather patterns, but when and how these changes unfold is difficult to predict because some changes will feed back into other changes that are not predictable.
Reporters often ask scientists if a particular abnormal weather event is due to climate change, and inevitably the scientists equivocate. It’s not that they don’t understand the connection, they equivocate because proving the connection requires long term records and identifiable patterns. Neither is true any longer. Weather is what we experience each day. Climate is the average weather over time. Weather extremes are breaking records and our climate is becoming increasingly chaotic. For example, scientists correlated some spring flood events with strong El Nino events; however, this springs flooding is driven by something other than a strong El Nino.
Scientists now recognize that climate change in the arctic is amplified from the loss of snow and ice warming northern arctic regions much faster than the lower latitudes. This arctic amplification is in turn causing a weakening of the Jet Stream, the fast moving current of air that divides the colder northern air from warmer southern air. The weakening of the Jet Stream is causing it to meander resulting in warm, moist air pushing farther northward and or cold arctic air patterns farther south. Severe weather occurs along the frontal boundary between cold and warm fronts.
Frigid cold artic air invaded the US last January as the Jet Stream plunged southward creating record breaking temperatures (in some places more than 50 degrees below normal.) The Jet Stream has made temperatures this winter fluctuate between abnormally cold and abnormally warm bringing periods of heavy snow, frozen ground, and rain across the Northern Great Plains and Midwestern US. Then March 10 Winter Storm Ulmer brought heavy snow and rain across the northern plains and Midwest. The pressure on old levee systems was too much and hundreds failed along the Missouri River, with some breaches causing catastrophic flooding in Nebraska and Iowa.
The Jet Stream is dipping much more than previously. The Weather Channel published a figure showing the dominant weather pattern from June – July 1993 that caused severe flooding that year. They identified “an unusually strong Jet dip” in the Jet Stream. Compare the figure from 1993 with another posted recently by the Weather Channel showing a much deeper plunge in the Jet Stream that is bringing storms and flash flooding across the US this week. What is interesting is how much deeper the Jet Stream is plunging compared to 1993, yet there was no mention of an “unusually strong jet dip”. Have we grown accustomed to seeing the jet stream plunge with deeper troughs and higher ridges? Is this the new norm?
Mississippi River Basin
The Mississippi River and its tributaries drains more than half of the continental US. It is divided into several large drainage basins including the Missouri River, the Upper Mississippi, the Ohio River, and Arkansas River basins. All of the soil is saturated in these drainage basins and most of the rivers are flooding. The division between the upper and lower Mississippi River occurs at Cairo, IL where the Ohio River joins the Mississippi and the volume of water from this merging is substantial.
There have been several “Great Floods” on the Mississippi River going back several 100 years of record keeping. One of the most destructive flood events occurred in 1927 and it resulted in substantial efforts by the US government to build control structures along the Mississippi river. The Mississippi River basin covers roughly 3.2 million km2 and is home to a more than $100 billion per year agricultural economy. Given the importance of this basin in terms of environmental processes, natural resources, and economics, it is important to understand how these factors may be affected by climate variability.
The US Army Corp of Engineers was given the mission of taming the Mississippi River after the devastating Great Flood of 1927. They built hundreds of miles of levees, outlets, and several important spillways to control flood water and prevent cities and towns along the river from being flooded. Changes in precipitation and runoff are increasing the need to open the spillways and more frequently damaging the levee system. There is danger that some parts of the flood control system could fail catastrophically.
The last two highest Mississippi floods occurred in 1993 and 2011. This year’s flood has many similarities to both. In the fall of 1992 and 2018 we had an above normal amount of precipitation and higher than normal snow fall during the winter. The last 12 months have been the wettest in US history going back to the 1850’s when we began keeping records. The wetter and snowier conditions across the northern plains and Midwest saturate soils and rain runs off instead of infiltrating. Runoff fills rivers and reservoirs forcing the US Army Corp of Engineers (USACE) to open the gates on dams to relieve pressure, exacerbating flooding.
Two principal spillways, the Bonnet Carre and the Morganza, were built to protect New Orleans. The Bonnet Carre Spillway was completed in 1931 and is comprised of 350 bays which are blocked by large wooden pins that are removed by a crane diverting water to the gulf through Lake Pontchartrain. When the spillway was opened in 1973 it was only the fourth time in its history that it was used and it was the first time the Morganza Spillway was opened. The Bonnet Carre spillway has only been needed 14 times in history and seven of these openings have taken place within the last ten years, four within the last three years, twice this year alone. The Bonnet Carre Spillway was fully opened for a record 75 days, from April 7th through June 14th, 1973. This year the USACE has had to open the Bonnet Carre Spillway twice, something that has never had to be done.
A similar situation occurred in 1993 when June flooding forced the USACE to open spillways. Rivers were still swollen from fall and winter precipitation and then in May and June the Jet Stream dipped, bringing warm humid air northward out of the gulf and a “parade of thunder storms” across the Midwest. This is exactly what we are seeing this May with precipitation well above normal.
Water continues to drain from the still flooded Missouri and upper Mississippi River basins. We are seeing one of the largest volumes of water to flow down the river since the 1927 flood. There are more than 350 rivers in various flood stage across the Mississippi River Basin.
The National Weather Service issued a warning in March 2019 that flooding will likely continue well into the summer and could be much worse in the event of any major storms. Similar to 2011 late spring storms are adding runoff to a system already full. This week we are witnessing a major storm event producing 8 to 10” of rainfall across the Arkansas River basin, a tributary of the Mississippi River basin. We are also seeing something that has not occurred before and could make this e situation even worse. This week the first named Atlantic storm of the 2019 season is occurring two weeks before the official start of the Atlantic hurricane season.
These signs point toward changes in water discharge to the Mississippi River confirming what scientists have predicted. In a warming world we will see more frequent storms with heavier rainfall. Flooding will become more common threatening levees, dikes, outlets, and spillways built to contain the mighty Mississippi River. How long before our control systems fail and results in a Great Flood event never before seen? How would such a flood event affect the people who live along this great river system, the third largest drainage basin in the world? How will this affect the US economy and its dependence on the Mississippi River for commercial transportation?
What is the long-term solution? Much of the damage in Nebraska was caused when more than 200 levees were breached. The USACE has warned that levees need upgrading and repair but few but the largest cities can afford the cost. The Mississippi River is a vital part of US commercial transportation. Flooding this spring has shut down traffic along the river, flood waters have spread out across farmland preventing spring planting and forcing many small farmers out of business. The Great flood of 2019 is still unfolding and we have yet to see the full extent of the damage. The Mississippi River basin and its tributaries are running full and there is little room for extra rain or storm surge.
It is hard to imagine what the impact would be of another Hurricane Katrina or Harvey. What would happen if the surrounding states had to absorb millions of refugees whose homes no longer exist? How many times can families or communities rebuild after storms and floods? If we cut taxes how long will the government be able to provide disaster relief to rebuild in the same location when it means the same disaster might strike again next year?
Collapse happens when a system is pushed beyond its ability to recover. It isn’t a question of ‘if’ a category 5 hurricane will hit a major city it’s a question of ‘when’. As the saying goes “What can go wrong will go wrong”…it’s simply a matter of time. The near misses won’t continue forever. The perfect storm of events (a major spring flood on the Mississippi and storm surge from a hurricane) could become the next “Great” storm that will destroy New Orleans. Or the Mississippi River could simply change its course and abandon the channel near New Orleans.
We don’t have the luxury of time to debate green deals or make long range plans to upgrade flood control systems. The time for adaptation has long passed. We can no longer solve problems, we must face the consequences. The best thing to do is to move away from the coasts and away from river flood plains. Let the flood spread out across millions of acres enriching farm land as it did for eons. Let the coasts rebuild salt marshes and wetlands that buffer hurricanes and storm surge. Yes, it will mean that some years farmers can’t plant early or at all. It will mean abandoning levees and removing structures resulting in perhaps trillions of dollars in lost real estate value, but the alternative will be worse. A catastrophic flood or hurricane will kill hundreds of thousands of people in a matter of hours.
The decisions we make today will determine how severe the impact of climate change will be. We can’t continue wasting resources fighting a losing battle to hold back the flood waters, rebuilding again and again in the same flood prone areas. It’s time to admit defeat and retreat to higher ground. The consequences of waiting too long to address rising greenhouse gases are now unfolding and the pace is increasing. This is the reality that is already here.