As of this writing, Typhoon “Ompong” (international name Mangkhut) is affecting millions of people in northern Luzon. In addition to those directly affected, millions more are being exposed to hazards such as flooding and landslides as Ompong enhances the effects of the Southwest Monsoon (Habagat). Meanwhile, on the other side of the world, Hurricane Florence is raging across parts of the eastern United States, forcing millions to evacuate.
In the coming days, as we assess the impacts of these two storms in their respective affected areas, a couple of questions will repeatedly come up. First, how much of these storms’ damages are a result of human-caused climate change? Second, how can understanding climate change help us better prepare for the effects of future storms and other extreme weather events?
What we have now come to realize is that the more refined our answers to these questions get, the clearer it becomes that these two issues are best addressed together instead of separately.
The first question is what climate scientists call the question of attribution. That is, how much of a storm’s effect can we attribute to climate change?
As recently as decades ago, scientists have been very hesitant to attribute the impacts of a particular storm to climate change. Previously, the most that scientists said was that for any given year, the likelihood of a very strong storm forming is increased because of climate change.
This statement is backed by at least two lines of evidence.
First, one of the fundamental rules of atmospheric thermodynamics predicts that as the oceans get warmer, there will be more energy and moisture in the air. This in turn means that developing storms will be more intense and have more water to suck in.
“Just as summer heat waves on land are greatly increased in frequency and intensity by even modest overall warming, so too are these ocean heat waves becoming more frequent and more extreme as the oceans continue to warm,” Michael Mann, director of the Earth System Science Center, told The Guardian. “All else being equal, warmer oceans mean more energy to intensify tropical storms and hurricanes,” says Mann.
Second, several studies suggest that very strong storms are occurring more frequently, a trend that will probably continue into the future. In other words, we must brace ourselves for more super typhoons.
Recently, however, an increasing number of climate scientists have suggested that we might be able to trace certain aspects of individual storms to climate change. In one pioneering study, Kevin Reed and his colleagues at Stony Brook University in New York argued that up to 50 percent of the rainfall due to Hurricane Florence might be traced to warmer temperatures caused by human activities. Reed’s team did this by simulating the behavior of Hurricane Florence first with human-caused global warming, and then without it. Their simulations showed that the storm is stronger (and also 80 km wider) because of global warming.
The study by Reed’s team comes on the heels of several pioneering studies published last year showing that three of the extreme weather events in 2016 were outside the bounds of natural variability and were therefore due to climate change.
One such event was the heat wave that hit South and Southeast Asia in April 2016. According to the studies, while heat waves hit the said region from time to time, some of them quite extreme, the 2016 event was beyond the natural range and can therefore be attributed to human-caused climate change.
As is usually the case in science, the scientific community is initially cautious in quickly embracing this new approach of attributing individual extreme weather events to climate change.
However, an increasing number of scientists are joining the effort to change this by improving the science of attributing extreme weather conditions to climate change. Such improvements will have many benefits, including helping local governments and communities better prepare for future events that are beyond the bounds of the previous normal and encouraging climate scientists to localize the methods that have worked elsewhere.
As the science of attribution of extreme weather condition is still being debated and refined, some have argued that preparing for future storms cannot, and does not need to, wait for improvements in the science. After all, we already know that the sea level is rising because of global warming. This sea level rise makes the storm surge of even normal storms much worse.
Furthermore, many have argued that the only thing we need to know to prepare is how bad things can get, and we already know that the worst will only get worse. This means our preparation should involve everything, from laws that enable government agencies, local governments, and communities to prepare for the strongest storms to come, to systems in place to help those affected by disasters.
Lastly, we can use scenarios backed by sound science not only to prepare for the worst that is to come but also to help us fight in avoiding them in the first place.
Pecier Decierdo is the resident physicist and astronomer of The Mind Museum.