What does it mean that the ocean is getting darker?
Every day I get Google alerts on a number of topics related to the ocean and science. These often frustrate me as I see serious problems that it doesn’t seem as if the public in general is taking seriously.
Last week I mentioned a report that indicated we have only explored less than 0.001% of the deep ocean. We have no idea what is down there but we are happy to allow deep ocean mining.
A story crossed my desk this week that I find just as troubling even if the overall mean is a little less clear.
Research from the University of Plymouth revealed that the ocean is getting darker. In the last 20 years it has darkened by 20%.
To back up, water absorbs light. Divers know this as they see red disappear in relatively shallow water. And the colors of the spectrum disappear within maximum recreational diving depths. Blue light waves penetrate the deepest into the ocean. But past about 200 meters/656 feet of sea water, there is no light left.
Now, imagine what it's like outside on a bright clear day, a hazy day and then an overcast day. The sun is the same, but the amount of it hitting the ground is filtered out.
The same is true in the ocean. If surface waters are getting darker, what does that do to the creatures that live in the sea? I know what it means for the garden or flowers.
We rely on the ocean in so many different ways, most of us don’t even consider it. Does this change cause deeper ocean animals to come closer to the surface looking for food? Does that increase pressure for food sources — meaning the fish many cultures rely on for protein sources may struggle? There are so many unanswered questions.
The cause for this darkening could be any number of reasons, but it is a safe bet that many are manmade, like increased pollution, agricultural runoff causing algal blooms and development causing stormwater runoff, or even plastics in the ocean.
It feels like the ocean is warning us there is a problem, but we aren’t paying attention to the signs and symptoms of a problem.
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