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Is climate change real? Ask a fish

By Sandy Branscomb, Guest Columnist • Apr 7, 2019 at 8:00 AM

Floods in the Midwest? Yes. Unprecedented wildfires in California? Yes. Melting glaciers? Yes. A 10-year warming trend in Johnson City? Yes.

That’s right. Temperatures in Northeast Tennessee are going up, too.

Before I retired from my position as a technical writer for a local software firm, I obtained an M.S. in marine biology and worked in several marine labs as a zoologist.

I have a small pond, one with goldfish, dragonflies, water striders, the occasional bullfrog. I have been monitoring its temperature every week for the last 10 years. The pond has supported fish, bullfrogs, tadpoles, and various invertebrates, including dragonfly larvae, water striders, copepods, and other microscopic organisms. It has had no chemical additives.

It has attracted raccoons, herons (both blue and green), predators on some of my unfortunate fish. It is a well-balanced ecological system. Although the fish have happily swum under 2-3 inches of ice in winter, it will be interesting to see if they survive increasing temperatures in the future.

Temperatures above 80 degrees begin to stress the fish. My pond got above 80 degrees 24 times from 2016 to 2018. Last year in July it reached 88 degrees and in August 86 degrees. Before 2016, it got as high as 81 degrees only twice, once in 2010, once in 2012.

The accompanying graph shows my measurements from January 2009 through today. Of course, the up-and-down plot reflects the seasonal temperature changes. Note how the past summer was far hotter than previous summers.

Look at the trend indicated by the straight line. It has an upward slope. No, it’s not a steep slope, but it is real, going up, and it's statistically significant. The probability of this line’s upward trend occurring by chance alone is only 5 in 10,000. In other words, my pond has been getting warmer over the last 10 years. Johnson City has been getting warmer.

So when you hear of unprecedented heat waves in Japan, Britain and the rest of Europe, out-of-control wildfires in Australia, rising sea levels in New Orleans, Miami, and Norfolk, Virginia, know that world-wide warming is real, and that it's affecting Johnson City, and you, too.

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