Too much of a good thing: the CO2 story

The CO2 in this picture is dramatized at ~1 billion times its actual size. Note: real CO2 doesn’t have eyes.

Scientists are trained to prefer being correct over being clear, and humor is discouraged in research journals, so you might imagine you’ve just stumbled onto the most boring imaginable blog outside of a live-tweeting of continental drift.  I’ll be trying to forget my training for the moment, however.  In truth, this is a wonderful chance to cast off the jargon, the equations, and the theories, and just try to convey some of my passion—a passion I share with most every Earth scientist I’ve met—for this glorious damp breathing rock we have the great fortune to be stuck to.*

But first, a confession… my role on this cruise is to do some brutal and uncalled-for things to carbon dioxide (CO₂) molecules in the seawater we’ll be pulling aboard.  I’ll be flushing them out of hiding with acids, driving them into a chemical soup designed to trap them, and then electrocuting them… all in the name of measuring how many of them are there.  I’m not without a heart however, and the least I can do for these unfortunate molecules is to tell their story.  As it turns out, their story is the story of life on Earth because these molecules do several things to keep our planet a pleasant place for life:

First, almost all known life continues because it uses some of the energy that is gained when sugars are metabolized (let’s say burned) into CO₂.  Those sugars were made from CO₂ in the first place, with the extra energy needed to turn them into sugars coming from sunlight or chemicals seeping from the Earth’s crust.  This is reason enough to like the molecule in my book.

CO₂ also keeps Earth from becoming just another oversized piece of frozen space debris.  Earth’s temperature makes the planet glow with an invisible ‘infrared’ light that CO₂ can absorb.  When CO₂ absorbs this light the light’s energy warms the atmosphere instead of being lost to space.  Next time you swim in the ocean instead of standing on it, thank CO₂.

Don’t try this at home… unless you live on a pier.

The last thing CO₂ does for us, and the thing we’ll be talking about the most in this blog, is regulating the chemistry of the oceans.  When it is dissolved in water, CO₂ reacts with the water to form an acid.  Now, seawater is already a complex chemical stew composed of salts and minerals washed off from land.  These chemicals have built up over many thousands of years as seawater evaporates, rains out over land, picks up more chemicals, and flows back into the ocean, again and again.  Without CO₂ the ocean would be really basic, which is the opposite of acidic.  Even with the acids from CO₂, seawater is still slightly basic compared to what comes out of your sink.

Hopefully you can now agree that CO₂ is a natural and fascinating piece of what makes Earth Earth.  The molecule is constantly dancing between the air we breathe, the oceans we swim in, and the plants and animals we eat to live… we owe the molecule a great deal.  Actually, we are the molecule in a way.

So, why have we turned on it?  Why is CO₂ suddenly the villain?  Why am I torturing this poor majestic molecule late at night in a metal box on the back of a ship lurching its way up the West Coast of North America??

CO2 doesn’t have horns, halos, teeth, or evil mustaches either. To be clear, it just has one carbon and two oxygen atoms.

Well, too much of anything can be dangerous, and CO₂ is no exception.  As you’re likely aware, starting with the invention of fire, we humans have been finding clever ways to make our lives better while adding more CO₂ to the atmosphere.  We’re burning fossil fuels for energy, making buildings out of cement (this also releases CO₂) and burning wood for warmth.  These activities have put CO₂ pretty far outside of the natural balances that we’ve had for the last several thousand years.  Already CO₂ is building up in the atmosphere, warming our planet and its oceans, and further drying out parched places while flooding wet places with rain that used to fall as snow.  Warming oceans hold less oxygen, and may start threatening the ability of some critters to breathe. Critically for this research cruise, CO₂ is building up in our oceans and souring the chemical stew that sea critters evolved to thrive in, and it is doing this faster than evolution can keep up.

So, CO₂ isn’t bad, it’s just out of balance.  I’m hopeful that we humans are clever and disciplined enough to find ways to continue to improve our lives without driving CO₂ too much further out of balance.  Even if we are that clever however, we’ll need to know how the CO₂ already added is affecting Earth’s life and climate, and that’s what we’re here to learn.  My role will be to carefully measure how much CO₂ is in the seawater to put the measurements of the other biologists and chemists into perspective.

* I’m assuming nobody is reading this from space, but, if you are reading this from space, please please send pictures.

Written by: Dr. Brendan Carter