Deep Ocean Impact From Climate Change 7x Greater by 2050 Than Today

Glass sponge found in the deep ocean   Photo: NOAA

A new study warns that climate change “velocity” in the deep ocean — the rate at which species’ range shifts in order to remain at their preferred temperature — is greater than at the surface even if we mitigate climate change, and particularly at depths below 600  and 3000 feet.   Surface warming is not expected to change nearly as much as the warming at deeper layers in the ocean, causing different velocities in different layers of the ocean.

Why This Matters:  The differences in water temperature increases at different depths in the water column could cause major disruptions in food webs as species that rely on each other for survival will have to adapt at different velocities, thus having major impacts on the distribution and abundance of ocean wildlife.  The overall impacts could be catastrophic because marine life in the deep ocean will be threatened increasingly through the end of the century due to warming regardless of our actions now.  Which makes it all the more important that globally we protect special areas in the ocean from other threats like mining and overfishing.  And we must anticipate species shifts before creating marine parks in the high seas so they actually can protect critical species and habitat.  

Glass Sponge Reefs, For Example

A different study found, similarly, that glass sponges have reduced skeletal strength and filter-feeding capacity due to warming ocean temperatures and acidification.  Glass sponge reefs are unique to the Pacific Northwest, and they play an essential role in  by filtering microbes and cycling nutrients through food chains, as well as for many fish and invertebrates, including rockfish, spot prawns, herring, halibut and sharks.  One of the study’s authors explains the significance of these reefs as “‘living dinosaurs’ thought to have been extinct for 40 million years before they were re-discovered in B.C. in 1986,” but now we know that their “sheer size and tremendous filtration capacity put them at the heart of a lush and productive underwater system.”  The reefs are giant — they can grow to 60 feet in height and are built by larval sponges settling atop the fused dead skeletons of previous generations — and they look like giant glass crystals.  But they are still a bit of a mystery — scientists know little about how these  will react to warming waters.

Oceans Have Layers

The researchers looked at the velocity of climate change at the various levels in the water column from the surface to the deep ocean, knowing that the velocity would be different at different levels.  What they found was that the rate of change varies greatly at different depths with the greatest velocity (7x the rate of change occurring today) found from 200m to 1km down – where the velocity is twice as fast as at the surface (3.5x the rate of change of today).   At the deepest levels the rate of change is 3x the rate of today.  But the impact of these changes on species may also vary since the deep ocean has a more stable temperature, even a tiny increase in temperature will have a huge impact on species, putting deep ocean species at great riks than those that live near the surface.

To Go Deeper: (lol a deep ocean pun) check out this interview with Vera Metcalf, Director of the Eskimo Walrus Commission, on indigenous knowledge and climate change in Alaska, among other things.  Also, tune into Capitol Hill Ocean Week, where a plenary panel will dive deeply into the ocean and climate change.

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