Climate Matters: Connecting climate change to extreme storms
Hurricane Helene brought historic and extensive flooding to the Southeast and parts of Appalachia, as trillions of gallons of water fell in a few short days. Just over a week later, Hurricane Milton rapidly became one of the strongest Atlantic hurricanes in recent history over record-warm Gulf waters. While these rare events resulted from several coinciding features such as natural weather variation and topography, climate change likely also played a role. Exploring these extreme events and their causes is important for forecasting future storms and determining what (or who) is responsible for the damage left behind.
Attributing extreme weather events to climate change is a pioneering field of research with varying levels of confidence depending on what is being studied. Temperature anomalies like heat waves or cold snaps are much easier to investigate than precipitation or specific storms. Temperature records have been more consistently maintained at thousands of sites worldwide for centuries, while precipitation recording is fewer and further between. Many climate models are also based on large-scale grid boxes where data is averaged over large areas. Precipitation amounts can vary drastically over short distances and can be overlooked by these coarse grids.
There are several methods of investigating extreme weather events to determine their causes. In rapid attribution studies, researchers can use models to simulate different versions of the atmosphere or compare events statistically to historical data. These methods are unfortunately undercut by the natural variation of weather every day, so solid connections are still difficult to make.
Several rapid attribution studies have been released on Hurricane Helene and its impacts. Researchers at Lawerence Berkeley National Laboratory in California say that climate change increased rain amounts from Helene by upwards of 50% and estimate that this rainfall was made 20 times more likely because of the effects of climate change. Michael Wehner, a senior scientist at the Lawerence Berkeley Lab, says these results are preliminary but corroborated by other studies. "When you look at this with different methodologies and different data sets done by different people, and they all come up with similar answers, our confidence in our attribution statement about how climate change impacted this event is increased." Dr. Wehner pointed to another report from ClimaMeter that assesses that rainfall is 20% heavier over the Southeast United States from storms like Hurricane Helene.
Dr. Wehner says that research on climate change attribution has also uncovered some surprises. "The surprising thing that we learned, with Hurricane Harvey, is that the number was so big." Michael says past studies of hurricanes have led to more confidence in more impacts from climate change. "There's somewhere, you know, usually greater than 20% increase in precipitation because of the climate change we've experienced mostly in our lifetimes."
As extreme weather attribution becomes a more grounded field it may have wide-reaching implications for who has to pay up after a disaster. If researchers can determine that certain weather events were made more severe by climate change, those responsible for that change could be met with litigation. Uncovering the influences of climate change will also improve weather forecasting as meteorologists learn more about what is driving specific changes in the environment.
