Cold temperature variability: An overlooked effect of climate change

A study led by Binghamton University has found that cold temperature variability is just as important as global warming for projecting the negative impacts of climate change. Cold temperatures are consequences of climate change that are often overlooked.

The research team investigated the effect of climate change on amphibian health, with an emphasis on their susceptibility to contaminants and parasites. Instead of focusing on the effect of rising temperatures, the researchers focused on the effect of cold and variable temperatures.

The analysis revealed that cold temperatures make amphibians more susceptible to road salt but less susceptible to parasites. Study co-author Jessica Hua explained that the findings highlight the importance of considering cold-temperature variability, and not just warming temperatures, when evaluating the impacts of global climate disruption.

“There is a lot of misconception that global climate change only refers to an increase in warming temperatures,” said Hua. “We feel that the research in this paper is important because it highlights that global climate change is more complex than just an increase in average temperature. In fact, global climate change is also predicted to increase the prevalence of extreme cold temperature events, as well as increase the amount of variation in temperature fluctuations.”

Study lead author Matthew Wersebe from the University of Oklahoma pointed out that many people overlook the impact of climate change on plants and animals.

“We all recognize that climate change is one of the most serious issues facing us today. However, as much as it is recognized as a serious concern for people, the impacts to animal and plant populations is much less front and center,” said Wersebe. “Along with this, many studies only consider warming, or changing patterns of water availability on natural systems, and not the impact of the variability in the short-term that is also expected with climate change. Studies like these are critical to understanding the full impacts of climate change.”

The researchers found that amphibians exposed to constant cold conditions as embryos were more susceptible to road salt contamination, but were able to recover with age. This is particularly relevant because the use of road salt will increase during extreme cold weather events.

Amphibians exposed to cold temperatures as embryos were also found to be smaller as they aged, and were slower to develop. This actually made them less of a target for parasites because their miniature size made them less attractive.

“We initially predicted that exposure to cold temperatures would be stressful to developing embryos. As a consequence, we expected that exposure to stressful conditions early in life would make amphibians less able to deal with other stressors later in life (i.e. parasites),” said Hua.

“We were also surprised because past studies have found that cooler temperatures can increase amphibian susceptibility to another parasite (the fungus, chytrid). In this case, the negative effects of the cooler temperatures on amphibians are driven by the fact that the fungus survived better in cooler temperatures.”

It is difficult to say whether the impact from the cold was harmful or helpful for the amphibians.

Wood frog embryos, Image Credit: Jessica Hua

“In some cases, exposure to cold temperatures was harmful. For instance: exposure to cold temperatures during the egg phase made young tadpoles more susceptible to road salt,” said Wersebe. “However, if we allowed these tadpoles to grow older, we found that exposure to cold temperatures during the egg stage no longer mattered for their susceptibility to road salt (i.e. older tadpoles were able to overcome the negative effect of embryonic exposure to cold).”

“Exposure to cold also made amphibians smaller – this is potentially harmful to amphibian populations because smaller amphibians have fewer offspring and this can over time potentially contribute to populations declines. Amphibian populations are declining globally, so considering the effects of cold temperatures may be important in understanding how to protect this imperiled group of animals.”

The study is published in the journal Ecology and Evolution.

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By Chrissy Sexton, Earth.com Staff Writer