How global warming is making Earth's climate more volatile
Scientists know that human-amplified climate change is increasing the frequency and intensity of many extreme weather events, but our changing climate could also be making wild weather swings more common and more extreme, according to new research published in Nature Reviews Earth & Environment and the Fifth National Climate Assessment.
For example, moving from devastating drought to record-breaking precipitation, or vice versa.
Parts of the world, like the southwestern U.S., historically experience highly variable weather and climate conditions, typically shifting from periods of very dry to very wet weather. However, in recent years, the rapid succession of extreme droughts, wildfires and floods has significantly impacted these regions, prompting scientists to look closely at how global warming affects climate variability.
The new research, which involved UCLA and UC Agriculture and Natural Resources, further investigated this variability, focusing specifically on hydroclimate volatility. Hydroclimate volatility is sudden, large and/or frequent transitions between arid and very wet conditions.
Researchers found that this volatility, also known as "hydroclimate whiplash," has become more frequent and will increase significantly as global temperatures rise.
The analysis found that since the mid-20th century, inter-annual hydroclimate volatility has increased by 8% to 31% over land areas, meaning more frequent shifts from dry to wet conditions in recent decades.
"This increase in hydroclimate volatility likely underpins a good portion of the societal perception that the impacts from climate change are accelerating," Daniel Swain, lead researcher and climate scientist with UCLA and UC Agriculture and Natural Resources, said in a statement.
To better illustrate their findings, the authors formally introduced the analogy of an "expanding atmospheric sponge," saying that the underlying physical processes driving the increase in volatility can be compared to using a kitchen sponge.
With each degree of global temperature rise, the hypothetical sponge becomes 7% larger, and, therefore, can hold more water. -- just like a larger kitchen sponge can soak up more water from the countertop compared to a smaller one. And when you wring out the bigger sponge, more water will pour out. A larger sponge will also require more water to become fully saturated.
A warmer atmosphere will also want to soak up more water vapor to achieve this through processes like evaporation, which can enhance dry conditions. These changes in atmospheric water vapor capacity will not only increase the chances of moving from very dry to very wet conditions, but it could fuel droughts and more extreme rainfall.
And as hydroclimate volatility continues to increase, more rapid swings between extreme weather events will amplify many of the associated hazards and potentially require changes to how we manage them.
-ABC News meteorologist Dan Peck