Finally, after establishing a historical baseline, the team used air and water temperature-based models to predict the frequency of future summer kills.
The outcomes were sobering. The models predicted a six-fold increase in the frequency of fish mortality events by 2100 based on local water temperature projections, while local air temperature projections predicted a 34-fold increase. Importantly, these forecasts were based on temperature projections from the most severe climate change scenario, which was the only one with the data needed for these analyses.
“If there are eight summer kills now, the models suggest we could have about 41 per year based on water temperature estimates or about 182 per year based on air temperature estimates,” Tye explained.
“We believe the water temperature model’s predictions are more realistic, whereas the air temperature model’s predictions indicate that we need to better understand how and why regional air and water temperature estimates differ over time in order to predict how many mortality events may occur.”
Nonetheless, their models show strong correlations between rising temperatures and the frequency of ecological disasters.
Despite the fact that the study used data from temperate northern lakes, Tye believes it is relevant to Arkansas. “One of the paper’s findings is that similar temperature deviations affect all types of fish, such that a regional heatwave could lead to the deaths of both cold- and warm-water fish,” he said.
“Specifically, climate change is more than gradually increasing temperatures because it also increases temperature variation, as we saw for much of this summer,” he said. “As a result, our findings suggest that these rapid temperature changes affect a wide range of fish, regardless of their thermal tolerance.”
“This work is important because it demonstrates the feasibility of using readily available data to predict fish die-offs,” Siepielski added.
“As with many other examples of how climate change is harming wild animal populations, this research shows that temperature extremes can be especially harmful.”
“The project’s large scale, with thousands of lakes and over a million air and temperature data points, is especially impressive,” Siepielski added. “Lakes outside the study area, including those in Arkansas and surrounding areas, are unlikely to be immune to the increasing frequency of these events.”