After pulling data from 1.6 million salinity profiles and data from the international Argo Program - a massive fleet of small oceanic robotic probes that gather information used by 50 research and operational agencies from 26 countries - scientists have found that the ocean has changed salinity levels over the past 50 years. The areas of the ocean that get the most rainfall are less salty, while the areas that get the least is getting more salty, revealing that our water cycle is getting more defined. The study, co-authored by CSIRO scientists Paul Durack and Dr Susan Wijffels, also confirms simulations by the IPCC that showed global warming impacting our water cycle. Those predictions of an intensified water cycle are playing out. Planet Save points us to the study, and according to CSIRO, the research finds a strong connection between "salinity changes at the surface driven by ocean warming and changes in the ocean subsurface which follow the trajectories along which surface water travels into the ocean interior." Because the changes in salinity are happening deeper into the ocean - farther than areas normally impacted by average rainfall - the scientists see this as a clear indication of broader, warming-driven changes.
"This is further confirmation from the global ocean that the Earth's water cycle has accelerated," says Mr Durack - a PhD student at the joint CSIRO/University of Tasmania, Quantitative Marine Science program. "These broad-scale patterns of change are qualitatively consistent with simulations reported by the Intergovernmental Panel on Climate Change (IPCC)."
The new observations will set a precedence for watching changes in global rainfall and the impact of warming on the earth's systems. Not only is ocean salinity affected, but water systems world-wide - dryer regions will get dryer and areas that receive higher levels of rainfall will get even more.
"Observations of rainfall and evaporation over the oceans in the 20th century are very scarce. These new estimates of ocean salinity changes provide a rigorous benchmark to better validate global climate models and start to narrow the wide uncertainties associated with water cycle changes and oceanic processes both in the past and the future - we can use ocean salinity changes as a rain-gauge," Mr Durack said.
The ocean's salinity levels have helped scientists understand warming in the past, including how major currents that regulate ocean temperature could shift with a change in salinity. And with changed currents comes changed weather patterns everywhere. Water cycles are a key area to watch as our planet changes due to warming and other human activity such as increased urban infrastructure and harsher agricultural practices. Changing the composition of the planet means altering not only where water falls, but also its ability to return to the water table. And that means a change in water supplies as well.
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