Sixty years of data shows more hot days, fewer frosty days in Nova Scotia

The number of hot days in Nova Scotia is rising while frost is forming less, according to research by Dalhousie University students.

Samantha Rebitt and Cambrie Levy just finished their first year in the integrated science program at Dalhousie.

The two analyzed data collected from 1960 to 2020 at eight weather stations across the province. They compared the first three decades to the next three decades to understand how the climate has changed.

"We found that the hot temperatures were becoming more frequent," Rebitt told CBC Radio's Mainstreet on Tuesday.

There were 14 more days in the second time period when the temperature climbed above 25 C, she said.

The biggest change, Rebitt said, was that there were 15 fewer days with frost between 1990 and 2020 compared to the previous 30 years.

"That kind of shows a shift overall in the general temperatures," she said. "Not only are average temperatures changing but also extreme temperatures are changing which can have implications on society, of course."

The research also measured the agricultural growing season. There was a range of differences across different weather stations from two more days to 14.5 days.

Rebbit said an increase of more than 14 days to the growing season would have both good and bad effects in Nova Scotia.

"Obviously, with a longer climate, hopefully the more crops you can produce," she said. "But at the same time, this warmer climate may introduce different diseases or pests or other invasive species that could harm the crop you're hoping for."

Another factor that would affect agriculture in the province is precipitation. The changes in precipitation levels were mixed across Nova Scotia, Rebitt said. 

The research indicated stations that were showing decreases in precipitation were located further inland while stations showing increases were located closer to the coast.

"Perhaps, coastal exposure may indicate whether precipitation is increasing or decreasing," said Rebitt. "We don't actually have any statistical proof for this. It's just a trend we noticed."

"Our study was really intended to look at the early signs of climate change," said Manuel Helbig, an assistant professor in physics and atmosphere science who was also involved in the study.