The Climate Change Eggsperiment
This is your egg on climate change. Any questions?
World leaders are meeting this week at the UN Climate Change Conference in Durban, South Africa, in a continuing saga of geopolitics. Debate centers on the question of how best to reduce global greenhouse gas emissions. The gathering comes on the heels of an important report showing that what goes up also comes down. Carbon dioxide not only pollutes the air, it turns the oceans acidic. When that happens, corals and shellfish die. It’s happening right now to oyster larvae in the Pacific Northwest.
Scientists knew this would happen. But it’s happening faster than many expected.
Here’s what’s going on: the world’s oceans are absorbing about 30 percent of the carbon dioxide humanity pumps into the air. When CO2 mixes with water, it forms carbonic acid (think soda bubbles). Carbonic acid dissolves calcium carbonate, a critical component in the exoskeletons of shellfish—including those we love to eat: lobsters, clams, mussels, oysters. Too much acid in the ocean, and we can kiss goodbye those oyster hors d’oeuvres.
We can pretty much say adios to a vibrant underwater world. “It’s just basically a moonscape. Nothing is living there,” journalist Elizabeth Kolbert described acidic seawaters during an October lecture.
Acidity and its counterpart, basicity, are measured on a pH scale from 0 (highly acidic) to 14 (very basic). The pH level of household bleach is 12 or 13, pure water is a neutral 7, tomatoes an acidic 4, vinegar 3, lemon juice 2. (You can find a handy chart here) Soda water typically ranges from 3 to 4, although some varieties contain additives to help neutralize the sour taste.
For a long time, the pH level of seawater was about 8.16. But that number has dropped (turned more acidic) to about 8.05 in recent years.
I remember Kolbert mentioning that coral will dissolve in vinegar. With that in mind, I decided to conduct a little experiment—with a few tweaks. I plopped one chicken egg, two clams and two mussels each into separate jars. I filled the first jar with vinegar and the second jar with soda water, then covered both. My husband propped up a camera and set it to take a picture every minute, for hours and hours (until the battery died, he replaced it, and the cycle continued). Click, click, click, all through the day and night.
Why the eggs? Obviously, ordinarily, chicken eggs don’t end up in the sea. But they do contain thin shells high in calcium carbonate. I thought they might provide interesting visuals.
Things happened inside those jars—much more quickly and dramatically in the vinegar. Little bubbles covered that egg, which started to float. Bits and bobs of gunk came off the clams and mussels, and then a couple of them drifted upward. The eggshell cracked.
The two jars sat nearly 24 hours before I opened the jars and examined the contents. I had started with tight-lipped clams and mussels, but a day in acid caused the shells to open and the flesh inside to bubble. That happened in both jars. But the vinegary egg revealed the most palpable results.
It was a rubbery, quivering blob. I rinsed it in tap water, and the auburn color washed away. The egg no longer had a hard calcium shell; nothing but a membrane held it together. I poked my fingers into its side, reshaping the egg as though it were a lump of silly putty.
Now, granted, this experiment was conducted for fun (and visual entertainment) more than scientific purity. It happened in our kitchen, not in a lab. I’m a journalist, not a scientist. But the results revealed precisely what scientists say will happen to a shell when subjected to acid.
If only that gelatinous gob of an egg could board a plane, fly to Durban and speak for itself.
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