New analysis shows that rising global temperatures have caused at least twice as much freshwater to shift from warm regions towards the Earth’s poles than previously thought. This is because the water cycle intensifies.
Research published in the journal shows that climate change has increased the global water cycle by as much as 7.4%, compared to previous modelling estimates of 2% – 4%. Nature suggests.
The water cycle describes how water moves around Earth. It evaporates, rises into atmosphere, cools, condenses and falls to the surface.
Dr Taimoor Sohail, University of New South Wales’ lead author of the study, stated that when we think about the water cycle, we tend to see it as an unchanging process that is constantly filling and replenishing our dams and lakes and our water sources.
Scientists know that rising global temperatures are increasing the global water cycle. This means that dry subtropical areas will become drier as freshwater moves towards more wet regions.
The sixth assessment report of the Intergovernmental Panel on Climate Changes was released in August. It concluded that climate change would cause long-term changes in the water cycle. This will lead to stronger droughts and more extreme rainfall events.
Sohail stated that freshwater volume had increased by a lot more than previously suggested by climate models.
He said that the IPCC’s dire predictions could be even more severe.
The scientists estimate that between 46,000 and 77,000 cubic kilometers of freshwater were shifted from warmer areas between 1970 and 2014.
We are seeing higher water cycle intensity than we expected. This means that we need to accelerate our efforts towards net zero emissions.
The researchers used ocean saltiness as a proxy to rainfall.
Sohail stated that the ocean is more salty in certain places than in others. When rain falls on the ocean it tends taints the water, making it less salty. Where net evaporation is present, salt is left behind.
Researchers had to account for water mixing due to ocean currents.
Sohail stated that they developed a new method to track how the ocean moves with reference for freshening and salinification. It’s like a rain gauge, which is always in motion.
Dr Richard Matear (chief research scientist at CSIRO Climate Science Centre), was not part of the research. He said that the study showed that existing climate models have underestimated the potential effects of climate change on water cycles.
He said that there has been a dramatic increase in our ability to monitor and record the ocean.
Observational datasets [like those used in the study]The time is right to reexamine how global warming might be affecting the climate system and the possible implications for important systems like the hydrological cycles.