The global water cycle – that is, the constant movement of freshwater between the clouds, land and the ocean – plays an important role in our daily lives. This delicate system transports water from the ocean to the land, helping to make our environment habitable and soil fertile.
But rising global temperatures have been making this system more extreme: water is moving away from dry regions towards wet regions, causing droughts to worsen in parts of the globe, while intensifying rainfall events and flooding in others. In other words, wet areas are getting wetter, and dry areas are getting drier.
Up until now, changes to the cycle have been difficult to directly observe, with around 80 per cent of global rainfall and evaporation happening over the ocean.
But a new UNSW-led study, published today in Nature, 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 findings show that between two and four times more freshwater has moved than climate models anticipated – giving us insights about how the global water cycle is amplifying as a whole.
“We already knew from previous work that the global water cycle was intensifying,” says lead author of the study Dr Taimoor Sohail, a mathematician and postdoctoral research associate at UNSW Science. “We just didn't know by how much.