“The risk of wind damage increases in most of the country,” says Ashbin Jaison.
That bad weather comes with a cost is no news, neither that everything becomes more expensive in the future. But how do you put a price on such a development?
In his recent PhD from the Geophysical Institute at the University of Bergen, and the Bjerknes Centre, Ashbin Jaison has done just that.
His analysis indicates that changes in climate and population could, in the worst case, triple the cost of bad weather compared to today.
Reckoning with risk
According to the Norwegian Natural Perils Pool, compensations of about 12 billion Norwegian kroner were paid after storms during the years 1980–2020, adjusted to 2015 value. Storms like Dagmar, Nina and Ole have a significant impact on the statistics, and wind damage was behind more than half of all insurance claims after natural disasters.
Ashbin Jaison’s calculations are based on these historical data, taking into account changing climate and population patterns. Strong winds cause more damage in densely populated areas than in mountain regions where no one lives.
First, he and his colleagues compared insurance payouts after storms with peak wind speeds. This allowed them to quantify the wind related damage in all Norwegian municipalities.
This strong wind over that many people – this much money paid out.
Then they extended this relationship to future climate and population figures.
Although the findings indicate that the strongest winds may become even stronger, there is considerable uncertainty associated with future weather, and thus also with the damage projections.
How we will build our houses and what we will fill them with, is hard to predict.
“We may also have more things to be damaged,” says Ashbin Jaison.
Heat waves and storms get worse
Ten to fifteen years ago, scientists were rarely willing to say that a certain winter storm or a heat wave was caused by climate change. Today, research into such question – event attribution studies – is an acknowledged research field.
“Attribution has developed a lot,” says Frauke Feser, a meteorologist at the Institute for Coastal Systems at Helmholtz-Zentrum Hereon, in Germany.
Today, researchers specializing in links between extreme weather and climate change, may comment on weather events almost before they have passed. Often, the conclusion is that bad weather would also have occurred in a preindustrial climate, but that climate change made the situation worse.
Frauke Feser and her colleagues have investigated how specific storms and heat waves in the past would appear in a future, warmer climate, or in a world without anthropogenic climate change.
She has specialized in a method where large-scale weather patterns occur roughly as they did, while temperatures and winds close to the ground develop as if the same situation had occurred in a warmer climate.
This way, one can assess the effect of future climate change on a specific event. Conversely, one can let the same weather system develop in a cooler climate than the present and estimate how climate change affected the situation.
Stronger winter storms
In February 2022 Germany and surrounding countries were hit by three winter storms. The first, Ylenia, shattered the windows of a ferry in the port of Hamburg. Together with her colleagues, Frauke Feser found that all three storms would have been stronger if they had occurred in a warmer world.
Using a similar method, her team found that the heat wave in Europe in the summer of 2022, was on average 1,25 degrees warmer than it would have been without the observed climate change.
That event was among the most extreme heat waves over the last two thousand years. In some locations climate change made temperatures 5,7 degrees higher.
Frauke Feser emphasizes that the winter storms attacking from the Atlantic Ocean vary greatly from decade to decade. From the 1960s till 1990 an increase in wind speed was observed, but today the values are back to average.
«No long-term change has been observed in recent decades,” she says.
Forecasting colors
Today wind warnings are sent out with yellow, orange and red flags to indicate danger. The system is based on wind speed, not on its impact. Only after the damage is done, can insurance companies release their reports.
In the future, Ashbin Jaison imagines that banks and insurance companies will be warned of expensive storms.
To go from meters per second to kroner, is difficult, but in collaboration with stakeholders, he hopes to see such a change.
“A traffic light system for risk,” he says. “Forecasts of wind damage.”