Freshening Up

Part of the Indian Ocean has been freshening up a bit. Water at its surface is getting less salty—a result of climate change. That could impact everything from the health of fisheries to the severity of winters in Europe.

Researchers combed through decades of records of the southeastern Indian Ocean, off the coast of Australia. They also looked at changes in global winds and ocean currents over the same period. They found that the ocean’s top 600 feet or so has become much less salty since 1960. The change was like adding more than half the water of Lake Tahoe to the region every year.

The “freshening” is driven by changes in winds and ocean currents. More water is being pushed into the region from the Indo-Pacific Freshwater Pool—a huge area with especially low salinity. And the trend is expected to continue in the years ahead.

Currents carry the warmer, lighter fresh water from the Indian Ocean into the Atlantic. It flows past western Europe, keeping the climate mild. But changes in the amount and location of the fresh water could alter the currents that carry it.

The freshwater layer can block water from the deep ocean from reaching the surface. Deeper waters hold more nutrients, which feed the tiny surface organisms that form the base of the marine food web. That could change fisheries and cause other difficulties.

So “freshening up” could be a problem for life both in and around the Indian Ocean, and far beyond.

The post Freshening Up appeared first on Marine Science Institute. The University of Texas at Austin..