Intertidal beaches like this one are experiencing increased salinity due to global warming.

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Researchers working along the Delaware Bay have discovered a new side effect of global warming: saltier beaches. Ocean beaches naturally contain salt; it’s a byproduct of the tides withdrawing. Such beaches, which are submerged under high tide but exposed during low tide, are favored by a wide variety of animals and plants, like crabs and thee birds that feed upon them. But increased salinity of beaches can have a big impact on the organisms living there.

Tests of the nearshore seawater by the beaches found that it contained 25 grams of salt per liter of water, but that the beach itself contained anywhere from 60 to even 100g/L, which was unexpected. This kind of increased salinity can only be caused by evaporation, which itself is impacted by changes in temperature and humidity of the type caused by climate change. Evaporation has a significant impact on subsurface water and what is known as pore water—water trapped between grains of sediment on beaches. Normally, as the tide goes out, it takes some of this pore water with it, maintaining the normal salinity of the beaches, but pore water is becoming saltier as there is less of it.

The researchers have taught us some new things about beach salinity, and hopefully that will lead to further discoveries down the road. In the meantime, increased global temperatures will result in more evaporation, which in turn means saltier inland and coastal areas. Increased salinity on the beaches could lead to a number of organisms moving away to find less salty locations in which to live. Salt isn’t all that great for soil, at least not in large quantities, so this could have an impact on plants and animals inland as well.

What we can do about this issue is as yet unknown, but now that we know the problem exists, we can start learning more and working on way to address it.