The global water cycle plays an important part of our environment and daily lives but rising global temperatures have been making this system more extreme.
The changes in this cycle are causing water to move away from dry regions towards wet regions, causing droughts to worsen in parts of the globe, while intensifying rainfall and flooding in others.
Before now, changes to the cycle have been difficult to directly observe, with around 80 percent of global rainfall and evaporation occurring over the ocean.
A new UNSW study has used changing patterns of salt in the ocean to estimate how much ocean freshwater has moved from the equator to the poles since 1970. The results show that between two and four times more freshwater has moved than climate models expected which gives us insights about how the global water cycle is increasing as a whole.
“In warmer regions, evaporation removes fresh water from the ocean leaving salt behind, making the ocean saltier,” says co-author Jan Zika, an associate professor at UNSW.
“The water cycle takes that fresh water to colder regions where it falls as rain, diluting the ocean and making it less salty.”
In other words, the water cycle leaves a signature on the ocean salt pattern so researchers can trace how the cycle changes over time.
When Dr. Taimoor Sohail, lead author of the study, and the team compared their findings to 20 different climate models, they found that all the models had underestimated the actual change in warm-cold freshwater transfer.
Dr. Sohail thinks the findings could mean we’re underestimating the impacts of climate change on rainfall.
https://phys.org/news/2022-02-global-amplifying-cycleand-faster.html