Impact on Demand – Number of Snowfall Days
Salt is used for de-icing, mainly to melt existing snow and ice, or to melt remaining snow and ice after snow-removal operations. Salt is also used as anti-icing agent. It is then proactively applied to driving or walking surfaces before expected precipitation of snow or rain and temperatures at or below O°C. Use of de-icing salt is limited to temperatures above -12 °C. Anti-icing helps prevent snow and ice from bonding to the pavement. Three parameters are important for the forecast of road-salt use:
- Change of the number of snowfall events with a change in climate
- Change of the number of days with temperatures below 0°C with change of climate.
- Change of the number of days with temperatures below -12°C with change of climate.
Other than might be expected, the number of snowfall events does not decrease simply in line with higher average temperatures. The map below shows the change towards more (blue) or less (red) frequent snowfall events.
Key points of the EPA study cited above are:
- Total snowfall has decreased in many parts of the USA since widespread observations became available in 1930, with 57 percent of stations showing a decline.
- Among all of the stations shown, the average change is a decrease of 0.19 percent per year. In addition to changing the overall rate of precipitation, climate change can lead to changes in the type of precipitation. One reason for the decline in total snowfall is because more winter precipitation is falling in the form of rain instead of snow. Nearly 80 percent of the stations across the contiguous 48 states have experienced a decrease in the proportion of precipitation falling as snow.
- Snowfall trends vary by region. The Pacific Northwest has seen a decline in both total snowfall and the proportion of precipitation falling as snow. Parts of the Midwest have also experienced a decrease, particularly in terms of the snow-to-precipitation ratio. A few regions have seen modest increases, including some areas near the Great Lakes that now receive more snow than in the past.
Snowfall events in the Southern US, where snowfall had not been observed normally, leads to over-proportional additional salt consumption. Authorities need to build de-icing infrastructure and create stocks of salt. Winter service needs to be quick, and thorough to avoid traffic breakdown and accidents with motorists that are not used to snow.
A study for Sweden, shows that snowfall related salt consumption is predicted to decrease in all parts of the country.
Figures: Left, map of investigated Swedish climate zones. Right, Salt use change in Gothenburg, Stockholm, and Sundsvall in the 21st century. Temperature-related maintenance is marked by solid lines, and snow-related maintenance is marked by dashed lines.
The increasing salt consumption for the Sundsvall region is temperature related and will be discussed in the next chapter of this blog. Overall, consumption of de-icing salt is expected to decrease with climate change.
In his recent thesis work: “Disentangling Drivers and Patterns of European Climate Change”, R. A. Brogli, describes the effects of climate change for all of Europe. According to the study, projected future precipitation changes in Europe exhibit a split pattern with increasing precipitation in the north and decreasing precipitation in the south year-round. Accordingly, de-icing salt consumption in the Southern part of Europe, and particularly in higher altitudes along the alps can be expected to decline with increasing temperatures and lower precipitation. The Northern part of Europe the situation is probably well characterized by the example of Sweden. Higher precipitation does for most regions not translate into higher snowfall frequency.
 Brogli R.A., “Disentangling Drivers and Patterns of European Climate Change”, DISS. ETH NO. 26388, Zürich, 2019.
 Arvidsson A.K. Blomquist G., Oeberg G., “Impact of Climate Change on Use of Anti—Icing and De-Icing Salt in Sweden”. TRB International Conference on Winter Maintenance and Surface Transportation Weather. 30 April – 3 May. Coralville, Iowa, USA 3-10, 2012.