In Minnesota, spring has long been known for rainy days and cherished rays of warm sun. This year, after the coldest winter in a generation, our thoughts turn more to umbrellas and sandbags. Any anticipation of summer has been put off by what seem like long stretches of increasingly heavy rain driven sideways by spring gales.
Last week our wet spring became something much more than just a delay of the summer we all deserve. Suddenly, stories of heavy rain consumed conversations on newscasts, water coolers and social media.
As with most weather events these days, the conversation eventually turns to the changing climate. The entrenched dig into their corners and those on the fence disengage, leaving just the loudest and most determined voices in the room. Both sides spout facts to support their contradicting arguments and eventually leave feeling more awful and discouraged than before. Perhaps science can provide some clarity where decades old culture wars and philosophical political battles have muddled the public discourse.
It is not your imagination; springtime in the Midwest has become much rainier over the last several decades. A number of recent studies have shown that heavy rain events are becoming more frequent throughout the warm-season here in the Upper Midwest, with the greatest change in the spring (April-June). On average, springtime heavy rain events have increased by nearly 10 percent since the 1960s. The newest generation of models suggest that this trend will likely continue into the future.
Given that global warming has very likely influenced local rainfall trends since the 1960s, is it fair to blame our recent record downpours on climate change? Perhaps an example from the boys of summer can guide us. Say a steroid-assisted baseball slugger has begun the season with an astounding 30 more home runs than any other year. He rolls into the All-Star Game at Target Field and launches a majestic shot into Target Plaza. There’s no way we can say that his All-Star Game homer was a direct result of the steroids, but we can confidently attribute his boosted seasonal total to them.
It is the same with climate change. We cannot say conclusively that global warming acts to intensify each individual storm, but we are increasingly confident that it has directly influenced the observed long-term increase in heavy rain events throughout the region. That is not to say that last week’s rains are not a result of climate change, but rather that it cannot be proven either way.
Even though we cannot conclusively attribute one event to climate change, we know that we are loading the dice in favor of these events becoming more likely. A single roll of the dice (i.e., weather) may not be affected, but after many rolls (i.e., climate) the loaded dice will be clearly apparent. When it comes to the intersection of global climate change and local weather, we ought to pay more attention to subtle, long-term changes in the weather rather than focusing on a single storm.
The scientific literature is full of studies and reports that document how heavy rainfall events are increasing. All of the best climate models show this trend continuing, maybe even accelerating, into the future. With such clear scientific agreement, it’s time we move past tired arguments and think anew about what we can do with the data we have.
So the next time the weather gets extreme — be it hot, cold, wet, or dry — let’s not retreat to our respective corners and debate the facts. Why try to debate if today’s weather is the result of climate change when the question is ambiguous by its very nature? Why not take a step back and ask whether the weather is consistent with long-term trends or a strange exception?
Sure, the answers to these questions may produce fewer fireworks around the water cooler or on Facebook, but at least they can move us closer to helping us decide how to respond.
Keith J. Harding is a native Minnesotan and an atmospheric scientist. He is a PhD candidate in Land and Atmospheric Sciences at the University of Minnesota in the Department of Soil, Water, and Climate.
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