Carbon Dioxide and Climate Change for Dummies

This post may be a bit longer than usual, so get comfy.

Click here for an index of earlier posts that touch on some of this.

When I was at Physical Therapy a couple weeks ago (my body is a traitor that seems determined to pay me back in full for all of the past abuses I inflicted upon it), Paul (the awesome P.T. dude) was telling me about how he had been at a large family get-together and was asked why he thinks that climate change is real — they’d apparently partaken of the Kool-Aid, and didn’t believe any of it. Since he is a real scientist, they figured that his version might be worth a listen, and were hoping for a rationalization in simple words and concepts they could all understand.

Well, he didn’t have one, so while he was moving my arthritic hands and wrists into unnatural positions that neither God nor Darwin ever intended, he asked if I had an explanation he could use to convert his relatives into true believers. I mentioned that I was somewhat distracted at the moment (acute discomfort can do that to me), but that I’d try to craft one once my focus could find some traction.

That time has come, but before we jump in and try to decide together if — and/or why — the climate is actually changing, a bit of background and a short discussion of terminology and motives might be in order.

“Climate Change” was originally called “Global Warming” by nearly everyone. This was based upon the observation that the earth’s ambient surface temperature is indeed warming! Clever name to be sure, but some equally clever folks immediately latched onto the obvious flaw and offered the equally clever observation that the earth wasn’t warming everywhere. The pundits were quick to point out that there are still miles of ice over Antarctica and Greenland, and snow still falls in Washington D.C. (but not yet at Mar-a-Lago).

Sadly, it is all too common for fanatics (on all possible ends of a continuum) to use a single contrary point to discount an entire concept. This has surely been done to plate tectonic theory — the overriding structural framework that explains our planet’s physical reality. Sure, there are oodles and scads of locations on the globe that don’t seamlessly follow the accepted model (I submit Africa as a case in point), but the general concept remains valid. We just don’t have the wits to completely understand the subtleties of plate motions (refer to the 1st Law of GeoFantasy for the legal justification), and need to do more research.

In any event, the same blanket rejection of Global Warming was attempted, with the ultimate realization that a more accurate descriptor would be helpful. Enter “Climate Change,” because that is really what’s happening — we still have colder and warmer regions, just not necessarily in the same locations or to the same extremes as before.

But no matter what you want to call it, the controversy over climate change — and humanity’s possible involvement — continues to rage: morphing in an unbroken continuum from complete denial that the climate is changing at all; through those who say that the climate may be changing but that humans are having no impact whatsoever; to those who say it is changing and that we might be affecting the process to some limited degree (but not enough to sabotage our economy); to those who say that human technological advancements are completely at fault, the climate would be as it was a couple hundred years ago if only Edwin Drake hadn’t discovered oil in Titusville… and we are doomed. (That these positions — especially the extremes — often seem to be politically motivated is surely beyond the scope of this blog.)

Since I have no interest in either 1) spouting bogus support for any of these differing views or 2) offering up hysterical predictions for the future, I’ll concentrate on what I know and can endorse: the science (based, as always, on what the earth — surely an impartial observer without any partisan agenda — can tell us). The good news is that the underlying fundamental roots and causes are simple.

The science of climate change hinges on the physical and chemical concept that atmospheric carbon dioxide is a greenhouse gas, and does the same thing to the earth that a car’s windows do to the temperature inside the vehicle. We all know the danger of leaving your dog (or baby) locked in your vehicle on a hot August afternoon, even for a quick run into the store, and a negligent driver can surely face legal consequences for even a momentary lapse.

Looking at the above graphic that compares atmospheric CO₂ levels with the extent of glacial ice, it is difficult to deny that the amount of carbon dioxide in the atmosphere has an impact on the surface temperatures found on the earth. It’s an unambiguous one-to-one relationship: when CO₂ levels fall, the climate cools and the glaciers advance; and when CO₂ levels increase, the climate warms and the ice retreats. (Click here for an earlier post for an introduction to glacial science.)

Also of note is the rate of change. Carbon dioxide may be added into the atmosphere over a relatively brief span of years (for whatever reason — large-scale volcanic activity immediately comes to mind), but it takes much longer for it to be removed (again, for whatever reason, but it’s not hard for me to imagine that plant life can only scrub it out of the air so fast — more on this in a bit).

But whatever the causes, look at how quickly the CO₂ levels can skyrocket; warming the climate and causing the ice to melt, and returning the water that was locked up in the cryosphere back to the ocean — anyone living near the beach during these transitions would likely have to put on his or her boogie shoes and head inland to keep in front of the rising sea level. (Click here for an earlier post linking glacial retreat to planet-wide fluctuations in sea level and the drowning of the coastlines.)

Take a closer look at the CO₂ graph in the image. The blue line indicates the historic trend over the past 400,000 years (these values are not made up, but derived from ice cores drilled into the Antarctic ice cap). The red line at the far right shows how CO₂ levels have increased since the Industrial Revolution began pumping carbon into the atmosphere; beginning at approximately 280 parts per million (ppm), but soaring to over 400 ppm after only a couple hundred years of industrialization.

There is one additional tidbit to be gleaned from these graphs: changes in the climate are nothing new; again as evidenced by the advance and retreat of glaciers, and apparently linked to the percentage of carbon dioxide in the atmosphere. This linkage had been established since long before humans began affecting the surface biosphere — indeed, the rock record indicates that what is euphemistically called an “icehouse earth” has been a regularly-occurring climatic adjustment going back hundreds of millions to billions of years.

There are those — many of them a lot smarter than me — who try to blame the burning of petroleum for the increase of CO₂ in the atmosphere (and therefore the changing climate), so let’s take a modest step back in time…

Sherman, set the Wayback Machine for 360,000,000 years ago, and set us down in West Virginia during what paleontologists call the Carboniferous Period on the Relative Geologic Time Scale. The Carboniferous lasted for approximately 60,000,000 years, and is broadly broken into two separate epochs: the Mississippian and Pennsylvanian (you can thank Titusville and Colonel Drake for this one).

The earth’s climate, not to mention the flora and fauna, were quite a bit different. It was hotter and wetter than what we see today, and there was a lot more carbon dioxide in the atmosphere — about 8X greater than current levels at the beginning of the Mississippian. (But CO₂ levels had dropped to about what we see today by the end of the Pennsylvanian. After 60,000,000 years of photosynthesis much of the carbon had been scrubbed, an ice age had begun, and glaciers were again advancing across the planet.)

Anyway, these climatic parameters contributed to the luxuriant plant growth that marked this blink of Earthtime. As such, the Carboniferous was a time when a lot of plants lived and died… leaving them to do whatever it is that plant remains do after they stop pulling carbon out of the atmosphere to make their cells.

Ahhh… death and (maybe) decay. When there is abundant oxygen in the atmosphere, most life forms — plants and otherwise — decompose (oxygen is a highly reactive element), but the elevated CO₂ during the Carboniferous limited the available free oxygen, and therefore the decomposition of the plant remains. As such, the organic plant residue didn’t decay like it does today, but began to build up on, and ultimately in, the ground. This essentially moved the carbon from the atmosphere into the rocks of the earth’s crust (expect a post on the Carbon Cycle at some point).

Thanks to the widespread bogs, fens, and wetlands that developed in so many portions of the globe (lots of water and plants will do that), the coal deposits that define the Carboniferous began forming almost immediately (giving the period its name). Coal is easy: all it takes is a swamp, some overlying sedimentary layers, and a bit of Earthtime to lithify the gunge and turn it into a layered sedimentary rock.

But the petroleum reservoirs took longer. The conversion of organic residue into oil is a much more complicated process, and required many millions of years for the dead plants to accumulate and mix in with the sediments (either terrestrial or marine will do), get buried under additional sediments which raised the heat and pressure, slowly change into oil, and then migrate into porous rock layers that can occur at depth in the crust.

So now we have all that carbon, separated from the oxygen in the atmosphere and stored in the rocks of the earth’s crust. But… carbon and oxygen absolutely love each other (imagine a little heart carved into a tree that says “Carbon loves Oxygen” on the inside), and they will enthusiastically renew their affair if they get a chance. Put them anywhere close (like in the carburetor of your car), add a few calories of heat, and it’s all but done. Hey presto: C + O₂ = CO₂!

The short version is that the earth took sixty million years to scrub carbon from the atmosphere and hide it in the ground as coal and oil, and now here we are: returning it back to the atmosphere as quickly as we can burn it to power our cars and generate electricity.

And as we add the CO₂ back into the atmosphere (already ramping up from about 280 ppm at the onset of the Industrial Revolution to the 415 ppm measured today), the greenhouse effect forces the surface temperatures to rise. To quote Mr. Miyagi: “Nature rule, Daniel-san, not mine.”

To my way of thinking, if we follow the science it is simple and unarguable: as the burning of fossil fuels converts the carbon in the coal and oil into carbon dioxide in the atmosphere, the surface temperature of the planet has to rise, leading to a changing climate. Post hoc ergo propter hoc, as Poppy would surely remind us.

So to close the circle and get back to Paul’s original ask: Are humans completely responsible for all of climate change? Absolutely not, but we are almost certainly contributing to it. And while the earth itself surely doesn’t care, the changes will continue to affect the biosphere, and the ability of humanity to maintain our accepted and familiar lifestyles.

One final point and a prediction for the future (I know I promised not to make one, but if our “lawmakers” can justify speaking without regard for the truth, who am I to do any different?): This is going to be a long-term issue, thanks to the increasing temperature of the ocean and the high specific heat of water.

(In case you were wondering: specific heat is a measure of how much energy is transferred when the temperature of a material goes up… or down. Water has a very high specific heat at 4.18 joules/gram, while the specific heat of just about everything else is well less than 1.0 joule/gram. This is why you need to use a potholder long before the water starts to boil.)

What this means is truly unfortunate for humanity, and many of the other species doomed to share this flicker of Earthtime with us: even if we stop burning oil RIGHT NOW and therefore stop adding CO₂ back into the atmosphere, the oceans — which are already measurably warmer than they were a couple hundred years ago and getting warmer — will take just as long to cool back down as they did to heat up. It is likely that, no matter what we do, the ice caps are going to melt, sea level will rise and flood the coastlines, and if anyone is still living near the beach they will probably want to relocate inland.

So it goes.