By Andrew Freedman
5 October 2015
(Mashable) – The epic amount of rain that led to deadly, catastrophic flooding across large parts of South Carolina and North Carolina is an example of exactly the type of supercharged storm system climate scientists have been warning about for years as a likely consequence of global warming.
This storm, like others that have come before it — from a massive deluge that flooded Oklahoma City to a flooding event in Houston, both of which occurred earlier this year — are examples of how the atmosphere is behaving in new ways now that there's more water vapor and heat for weather systems to work with.
It's not that heavy downpours and floods didn't occur before manmade global warming became evident (for the record, they did). The issue now is that these events are even more severe than they otherwise would have been. And they are becoming more frequent in many areas.
Though there are significant limits on what climate scientists can say at this point about an event like the South Carolina floods, it's well-established that global warming has already led to a measurable increase in global atmospheric water vapor levels, and this moisture can be wrung out as heavier bursts of rain or snow.
It is also well-established in scientific literature that precipitation is increasingly falling in short, intense bursts rather than long-lasting, generally lighter events.
The risk for extreme precipitation events is increasing in many parts of the world.
One study, for example, showed that a 1-in-100 year winter-rainfall event in parts of the United Kingdom is already occurring more frequently, becoming a 1-in-80 year event.
This means that an event with a 1% chance of occurring each year now has a 1.25% risk of occurring in any particular winter, which translates to a 25% increase in risk, according to Oxford University scientists. [more]