How do scientists determine whether climate change is driving extreme weather events like the floods, heat waves and droughts that we’re experiencing today? To find out about the science of attribution, Mongabay’s Kristine Sabillo recently interviewed environmental statistician Clair Barnes of World Weather Attribution (WWA), a global network of researchers that has been analyzing the role of climate change on today’s extreme weather.
The idea behind WWA, Barnes said, “was to look at high-impact weather events and to use the latest science to say something while the conversation is still going on.”
WWA works with partners like the Red Cross Red Crescent Climate Centre that monitor various emergency and disaster alerts channels and issues what it calls a “trigger” when a disaster has major humanitarian consequences. This can be a heat wave setting temperature records in a region, or a flood killing or displacing a certain number or proportion of the population.
Once WWA researchers decided on an event to study further, they work with local experts who understand the meteorological and geographical processes behind that event. A rapid analysis can take from a few days to up to a few weeks to finish.
Barnes said they use observational weather data and statistical and climate models to understand the role of climate change in the event.
Consider flooding in a river basin due to heavy rains over three days: The researchers use multiple weather data sets to examine how the maximum three-day rainfall period for that season has changed in that area over the past several years. A statistical model then tells them how the change in rainfall is related to the change in global mean temperature over the years. The latter, scientists have established, has risen mainly due to human-triggered greenhouse gas emissions. Using the models, the researchers then calculate how likely such heavy rain and flooding is in today’s climate compared to pre-industrial times, when temperatures were much cooler.
The researchers further use different climate models to see how much climate change, rather than other factors such as deforestation, influenced the flooding event.
But there are data challenges, Barnes said. While some regions like Europe have good availability of both observed weather data and climate models, others, like parts of Africa, don’t.
Still, it’s important to do the rapid studies and get the reports out quickly, Barnes said, “not only to say actually it was climate change, but sometimes to say: we’re not seeing evidence that climate change was what caused these terrible impacts. Maybe it’s that the infrastructure wasn’t maintained, or it was something that we could have avoided in another way.”
Barnes added that while other meteorological agencies around the world are doing similar attribution studies, WWA will continue to analyze weather events, especially highlighting regions that are underrepresented.
Read the full interview here.
Banner image: Rescuers evacuate people from a flooded hospital following landslides and flash flooding in India’s northeast state of Manipur. (AP Photo/Donald Sairem).
