Climate Change Surprise!

When I was growing up, I hated April fool’s day. I was the youngest of three, which meant that every joke would be at my expense and I was never quite old enough to exact adequate revenge. Every year I ended up covered in shaving cream, doused with water and sitting on whoopee cushions. Hot pepper gum and hand-buzzers were made for people like me. At the time, my brain was not developed enough to come up with a clever prank, so I swore that one day when my brothers least expected it, I would exact my revenge. Some day.

Years passed. Decades even. We became adults, moved on, got jobs, met for drinks. The little things of childhood seemed petty. When I turned 30, I knew that the time had come. I enlisted my brothers’ girlfriends as allies (clarification: two brothers, one girlfriend each). In the early morning on April 1st they snuck out of their rooms and coated all the door handles in the house with shaving cream. You may not think this was a significant enough revenge, but then you probably have never gotten a hand-full of shaving cream on a trip to the bathroom in the middle of the night. Trust me, at 2am there is nothing you want less. The transition is quick, from confusion to realization to rage.

The next morning I gleefully received several angry texts – revenge 25 years later is as sweet as it sounds. As you can guess, in my old age, I have developed a liking for surprises. And it’s this love of surprises that allows me to enjoy learning about climate change so much—climate change is full of surprises.

Take oceans—I’ve talked about the effect of climate change on oceans….the effect of acidification on sea animal’s senses, and their sex life… the effect of warming on kelp… increased carbon dioxide on sea anemones… altered pH on shelled organisms….what else could I possibly write about?? There can’t possibly be anything else.

Well, there’s one more thing….and that’s oxygen.

Surprised?

It turns out that ocean water holds less oxygen when it’s warmer. And though sea animals are able to breathe underwater, they are actually breathing the oxygen in the water. In addition, for some ocean ectotherms (animals whose body temperature changes with the environment), increasing the temperature increases their metabolism, requiring even more oxygen. So as less oxygen is available in the water, their need for it grows greater.

This is predicted to be a particular issue for the Antarctic clam, which is a popular model organism. When I say model organism, I don’t mean Tyra Banks or Kate Moss, I mean a model that is used to make connections and observations for other similar organisms (Tyra and Kate don’t really qualify here). Mice are a model organism, and so are fruit flies. They are easy to control, their life span and characteristics are well-understood, and they reproduce like it’s going out of style. They are a “model” in more way than one. So though I’m speaking of the Antarctic clam, the findings are not limited to this lowly clam, it is a model for other similar animals that like to live at the bottom of the ocean, feed larger more ferocious animals and slurp on sea scum.

So what is going to happen to these bottom dwellers? It turns out that older, larger clams are negatively impacted by lower oxygen levels in the water. Part of this has to do with older clams being more sedentary (yes, even older clams mellow with age), and part is due to other factors like the size of the gill surface for oxygen extraction (older animals have proportionally less). If you have less surface area for extracting oxygen, and there is less oxygen in the water…well, let’s just say it’s bad news, clam (1).

But so what? That could be a good thing, right? More room for the small, nubile clams. Out with the old, in with the new! But in this species the older, larger, lazy clams are the reproducing clams, so you are less likely to get the young and new without the old and large. Troubling for the clams. Troubling for us who care about ocean ecosystems.

So, climate change is more like a vengeful little sister than you had ever imagined. Just when you thought you knew everything about it, it turns out it is full of surprises.

Further Reading:
(1) Hypoxia impacts large adults first: consequences in a warming world.


Minda Berbeco has a PhD in Biology from Tufts University and is the Policy & Programs Director at the National Center for Science Education. She was considering playing a prank on her coworkers this year for April fool’s day by telling them she had been offered a job by the Heartland Institute, but then realized it just wouldn’t be that funny.

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