The stripes kind of look like those old packs of Fruit Stripe bubble gum. Each stripe represents a year. The colors, shaded from cool navy to scarlet, indicate annual average temperatures.
Together, the stripes reveal patterns of warming trends across the globe over the last 100-plus years.
Climate Scientist Ed Hawkins created the graphics to start conversations about the warming world and the risks climate change poses in different regions.
To that end, I spoke with Kentucky State Climatologist Stuart Foster about Kentucky’s stripes, what they mean and how the changes they imply will impact the state’s future.
What’s Up With Kentucky’s Stripes?
Kentucky has seen about a 1.5 degree increase in annual average temperatures since the 1970's, but Kentucky’s stripes meander from blue to red and back again without showing the definitive warming trends seen in global averages.
From a climate perspective, Kentucky is similar to other states located in the Southeast U.S. Both have experienced periods of warming and cooling. So it’s not just Kentucky, it’s really the Southeast U.S. that has been something of a “cool island” or an anomaly.
“Instead of a staircase, or a ramp or an incline, in terms of increasing temperatures. We’ve been more of a rollercoaster,” Foster said.
As for why, it’s not really clear, he said. One theory is that the southeast of the U.S. might be impacted by cyclical changes in ocean temperatures. Others speculate that changing agricultural and land-use patterns may be a factor in the Southeast staying relatively cool.
Still, the temperatures do show a consistent pattern of warming, particularly over the last five decades, Foster said.
Can We Draw Historical Parallels?
Kentucky is seeing temperatures similar to what they were at the first half of the 20th century. That also happened to be a time when Kentucky’s weather was pretty wild.
From the 1930’s through the 1950's, Kentucky experienced a higher frequency of droughts and heatwaves. And in the same period, Louisville experienced the Great Flood of 1937 that inundated two-thirds of the city.
Weather over the last decade has seen similar parallels in terms of temperatures, but it's also a lot wetter.
“In contrast while overall the average temperature is similar, we’re in a much wetter period," Foster said. "In fact, the last decade or so is the wettest such period on record in Kentucky going back to the late 1800's.”
Foster pointed to extreme rains in 2010, which were followed by a drought. Then in spring in 2011, flooding along the Ohio River gave way to a drought the following year in the western part of the state.
2018 was the wettest year on record in the state, and this year is shaping up to be another soggy one. While it can seem counter-intuitive, heavy storms and precipitation are consistent with a warming climate. That’s because warmer air can hold more moisture, making for bigger storms.
“We could indeed have both increased risk of flooding and at the same time, increased risk of low-flow conditions where we have heatwaves and droughts that develop,” Foster said.
Should We Consider The Extremes?
Foster pointed out the map is based on annual average temperatures. That’s great for getting the big picture, but tends to gloss over the nuances in any given year.
And really, it’s the extremes that matter, he said. It's the small increases in temperature over time that raise the likelihood of extremes.
“But when it comes to impacts, it’s not the change in the average that matters, it’s the variability and the occurrence of these extremes,” Foster said.
Farmers are already dealing with these realities every day, he said. There were counties in southwestern Kentucky that saw 12 to 15 inches of rain in February alone. That weather forced farmers throughout the region to put off planting their crops, though most in Kentucky have been able to get them in the ground now.
In Kentucky, the changing climate will increase the prevalence of pests, disease rates, allergies and heat-related illnesses. Extreme weather events can impact tourism, transportation and energy prices, among other parts of the economy.
But Foster also sees a silver lining for Kentucky. The state’s abundance of fresh water will be a benefit relative to other states impacted by climate change.
“As temperatures warm and population grows, and water becomes a more water valuable resource,” Foster said. “Kentucky stands to be at an advantageous position.”
