"With an uncertainty of 900%, weather attribution specialists stand ready to contribute to the conversation about the urgent need for climate action.
Is climate change to blame for extreme weather events?
Attribution science says yes, for some – here’s how it works
August 25, 2021
Xubin Zeng
Professor of Atmospheric Sciences and Director of the Climate Dynamics and Hydrometeorolgy Center, University of Arizona
Extreme rainfall and flooding left paths of destruction through communities around the world this summer.
The latest was in Tennessee, where preliminary data shows a record-shattering 17 inches of rain fell in 24 hours, turning creeks into rivers that flooded hundreds of homes and killed at least 18 people.
A lot of people are asking: Was it climate change?
Answering that question isn’t so simple.
There has always been extreme weather, but human-caused global warming can increase extreme weather’s frequency and severity.
For example, research shows that human activities such as burning fossil fuels are unequivocally warming the planet, and we know from basic physics that warm air can hold more moisture.
A decade ago, scientists weren’t able to confidently connect any individual weather event to climate change, even though the broader climate change trends were clear.
Today, attribution studies can show whether extreme events were affected by climate change and whether they can be explained by natural variability alone.
With rapid advances from research and increasing computing power, extreme event attribution has become a burgeoning new branch of climate science.
The latest attribution study, released Aug. 23, 2021, looked at the rainfall from the European storm that killed more than 220 people when floods swept through Germany, Belgium, Luxembourg and the Netherlands in July 2021.
A team of climate scientists with the group World Weather Attribution analyzed the record-breaking storm, dubbed Bernd, focusing on two of the most severely affected areas.
Their analysis found that human-induced climate change made a storm of that severity between 1.2 and 9 times more likely than it would have been in a world 1.2 degrees Celsius (2.1 F) cooler.
The planet has warmed just over 1 C since the industrial era began.
How can anyone say with a straight face that attribution science is adding value to the conversation, when the best they can achieve is an uncertainty of 900%, and a bottom limit of no change in severity whatsoever?
The bottom limit of 1.2 times worse seems indistinguishable from business as usual, or even a slight reduction in the severity of weather, with an uncertainty of that magnitude.
I have no problem with people working to understand how CO2, weather and climate change interact.
But in my opinion a branch of scientific analysis which apparently cannot distinguish between an unfolding catastrophe and business as usual
is way too immature to add any value to the public discussion about climate policy."