Study: Decline in frost days will negatively impact ecosystem

The average number of frost days in the Czech Republic, that is days when the minimum daily temperature falls below freezing point, has gradually been falling, according to newly-released data by the Czech Academy of Sciences. Experts warn that this could have a lasting impact on the ecosystem.

Since the early 1960s, the average number of frost days in the Czech Republic has dropped by 4.7 every decade. While between 1961 and 1970 there were an average of 126.5 frost days each year, between 2011 and 2020 there were only 99.8. This decade saw the fastest decline, with 11 frost days fewer than in the previous one.

Just as frost days are decreasing, so are icy days, when the temperature doesn’t rise above zero for a whole day. That decline is even more pronounced, says Pavel Zahradníček of the Institute of Global Change Research of the Czech Academy of Sciences:

“The drop in the number of icy days is even higher. In the 1960s we observed about 47 icy days per year but in the last decade it was only 23 days. That is a drop by 50 percent and it is a really significant change of the climatic index.”

Pavel Zahradníček says the current temperature trends and data are not surprising, as they are in line with 15-year-old predictions. However, they are closer to the pessimistic scenarios.

Photo: Štěpánka Budková,  Radio Prague International

The estimates are based on the amount of carbon dioxide emissions in the atmosphere, with the pessimistic estimate working on the assumption that emissions will not be regulated in the future, while the medium estimate is based on the assumption that emissions will be regulated but not strictly limited.

In the Czech Republic, temperatures have been increasing throughout the whole year, but in the winter and summer, the changes are more pronounced than during the other seasons.

The decline in frost days can have a lasting impact not only on the country’s ecosystem, but also on the economy or water supplies, says Mr Zahradníček:

“Frost days are very important for the Central European climate and landscape. With the decreasing number of frost days, we also see fewer days with snowfall and snow cover.

"And snow cover and snowfall are very important for saturating the groundwater reserves. That was one of the reasons that caused the droughts in 2015 or 2020.”

Warmer winters with fewer frost days also have a negative impact on vegetation and soil, says Mr Zahradníček, namely on fruit growers in warmer regions of the country.
The earlier end of winter and the onset of spring wakes up the trees earlier, but the risk of April frosts remains the same.

While there is currently a 25 per cent chance of frost damage to flowering trees in South Moravia, by the end of the century it could move up to 60 per cent, which is once in two years.