Midwestern Rains Putting a Damper on Summer? It Gets Worse with Climate Change

, senior climate scientist | July 23, 2015, 4:09 pm EDT
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This summer has been a remarkably wet one in the Midwest, punctuated by a few really big downpours. The increase in heavy precipitation has disrupted farming, increased flooding, and threatened cultural landmarks. Recent science tells us that extreme rainfall will become more common in the Midwest if we continue to pump more greenhouse gases into the atmosphere.

Extreme downpours

Here in Chicago, rain has been so common that it has become a running joke between me and my wife. “It’s raining again,” she says. “Oh good,” I say. “It will break our 12-hour drought.”

We weren’t laughing, however, when a strong storm blew through a few weeks ago. A tornado warning threatened our neighborhood, and flooding in our basement damaged some irreplaceable family pictures we had stored down there.

That storm contributed to what was the wettest June on record for three states – Illinois, Indiana, and Ohio – with precipitation levels above average for much of the Midwest. And July has shown no signs of slowing down.

Map of US showing ranking of statewide precipitation for June 2015

Illinois, Indiana and Ohio just experienced their wettest June on record, and much of the Midwest was wetter than normal. Shades of green show higher-than-average precipitation; shades of orange show drier-than-average precipitation. Numbers indicate the ranking of June 2015 relative to other years in the historical record, ranging from the driest year (rank of 1) to the wettest year (rank of 121). Source: NOAA

Soggy fields lead to late planting and poor crops

We often think about drought as the biggest threat to farmers, but wet conditions can also have a damaging impact. Heavy and frequent rains have kept farmers from planting their fields this summer, or have drastically reduced the yield of crops already in the ground. In central Missouri, for example, acres planted in corn and soybeans are far below normal for this time of year, due to wet conditions. And wheat harvests have been hit hard, dealing a double whammy to farmers: yields on each acre are far below normal, and the poor quality of the grain is fetching low prices for whatever wheat they manage to glean from the fields.

Trend: heavy rains are becoming more frequent and intense in the Midwest

For the Midwest, the conditions we’re seeing this summer are part of a longer trend: heavy rain events have become more common over several decades, with a trend toward larger events since the 1980s. The heaviest rain events have also dropped more water than in the past – the most extreme Midwestern storms in 2000-2012 dropped more than 30% more water than the most extreme events in 1901-1960. So if you think storms are happening more often and they’re getting more powerful than they used to be, you’re right.

It’s an indication that something weird is going on, like when baseball players suddenly started hitting a lot more home runs. In this case, it’s a sign of a climate system on steroids, and it’s pumping a lot more water into storm systems.

Chart showing increase in amount of precipitation in the heaviest Midwestern storms

In recent decades, the heaviest storms of the year have been dropping much more precipitation than in previous decades. The bars indicate the percent changes in the annual amount of precipitation falling in very heavy events, defined as the heaviest 1% of all daily events from 1901 to 2012. The far right bar is for 2001-2012. Changes are compared to the 1901-1960 average. Source: NOAA NCDC / CICS-NC

Cultural heritage at risk

My flooded basement put my personal heritage at risk when my family photos got soaked. The same thing is happening on a much larger scale with our cultural heritage. In 2008, floodwaters devastated several cities in Iowa, including extensive damage in historic downtown Cedar Rapids. Many compared those floods to the much more extensive floods of 1993, which damaged towns across the Midwest. The floods that year were so severe and widespread that ten years later, FEMA compiled a retrospective look at the lessons learned from the disastrous flooding of 1993. Those lessons called for better floodplain planning and management, greater emphasis on flood insurance, and flood mitigation efforts to “end the desperate cycle of repetitive flood losses.” Those lessons may become even more important in the future, as precipitation events become more extreme.

Map of Midwestern states, showing projected increases in days with heavy precipitation

Heavy precipitation events will become more common if heat-trapping emissions continue to increase. The map shows projected changes in the number of days with very heavy precipitation (top 2% of all rainfalls each year) for the middle of the current century (2041-2070) relative to the end of the last century (1971-2000) across the Midwest under continued emissions (A2 scenario). The highest part of the range implies that heavy precipitation days would become at least 20% more frequent under this scenario. Source: National Climate Assessment

With climate change, it will get worse

The trends toward heavier, more frequent storms in the Midwest, and the damage that they cause, are consistent with what we’re seeing globally. A recent global study found that the warming climate led to 12% more record-breaking rainfall events than expected in the period 1981-2010, a significant increase over the time period from 1901 to 1980. The Midwest is one of the regions where heavy precipitation is projected to increase and heavy storms will become more frequent (see map below) if heat-trapping emissions continue to grow. Prudence would suggest that we begin planning for this today, even as we seek ways to slow the pace of climate change.

Vulnerability doesn’t have to mean that we will lose the things we love             

A detailed documentary by the University of Iowa explains how the floods of 2008 threatened much of the university campus, but thanks to the incredible efforts of thousands of volunteers, university employees, the National Guard, and others, the damage was limited and the most important assets were saved. This kind of effort exemplifies communities at their best, coming together in the face of adversity. The places we love are worth saving, and most of us would gladly lend a hand to help protect them.

But if these risks are allowed to increase, there will come a point when repeated storms, crop damage, and flooding outstrip our capacity to respond. People will have to face hard questions about what is worth saving, and what will have to be abandoned. Will this be the year that farms are sold off and converted to a wildlife refuge? Will this be the flood that makes an historic church unusable? Will flooding finally force us to sever cultural landmarks like the Farnsworth House from their historical context? These are real, irreplaceable, and disruptive losses for the communities where they occur. While it’s true that we live in a world of constant change, it’s heart-wrenching to think that these losses might have been avoidable with a little more foresight. By using better foresight today, we can safeguard our heritage for the future.

Future losses aren’t a foregone conclusion: we can take action to protect ourselves

I recovered most of my soggy family photos and moved the most valuable items high off my basement floor. The governor of Iowa called in the National Guard and other resources to protect the University’s most valuable assets. From our own individual homes to the planning of our cities and watersheds, we can learn the lessons, take more precautions, and make better preparations for the future.

At the same time, we face limits to how much we can protect ourselves – affected communities will need outside assistance, while the rest of us begin to tackle the root of the problem. We can support steps that diminish the pace of climate change by reducing the activities that add greenhouse gases to the atmosphere. The federal Clean Power Plan is a step in the right direction, but it won’t be enough on its own. We will need the U.S. to do more to shift its support away from fossil fuels and into emissions-reducing technologies, if we are all going to reap the benefits of global action on climate change.

As a commentator said about steroid use in baseball: “It was good fun while we were all ignorant. Now that we’re not, we should all be able to agree with the following sentiment: Let’s not go through all that again.” It’s an apt sentiment for the climate, as well. Summer storms can be good fun, but we should all be able to agree that we don’t want to jeopardize our heritage and put our kids and grandkids at greater risk. Let’s move our climate past the steroid era.

Posted in: Global Warming

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