Energy Innovations: Geochemical, Sunlight, Oxygen, Flesh, Fire
May 25, 2017 7:58 PM   Subscribe

Olivia P. Judson in Nature: "Over the course of Earth history, the harnessing of free energy by organisms has had a dramatic impact on the planetary environment. Yet the variety of free-energy sources available to living organisms has expanded over time. These expansions are consequences of events in the evolution of life, and they have mediated the transformation of the planet from an anoxic world that could support only microbial life, to one that boasts the rich geology and diversity of life present today. Here, I review these energy expansions, discuss how they map onto the biological and geological development of Earth, and consider what this could mean for the trajectories of life–planet systems elsewhere."

Among the Implications: "This Perspective further suggests that, through the harnessing of fire as a source of energy, Earth has now arrived at a new inflection point. Considering life–Earth history through the lens of energy expansions supports the view that the Anthropocene is a genuinely novel phase of the planet's geological and biological development—a conclusion independently reached by Lenton and colleagues."

The Atlantic has it in layman's terms (although the Nature paper is very readable!).
posted by Eyebrows McGee (11 comments total) 27 users marked this as a favorite
I wasn't sure exactly what she meant by "Shifts in biogeochemical cycles".

Great article!
posted by rebent at 8:37 PM on May 25, 2017

Yeah, I had never heard the term before! It's how biological processes affect geological processes, and I had not really thought about that before, but obviously we cycle carbon and oxygen and so on in and out of the earth itself, and obviously that affects the geology of the planet! Like, I knew it happened, but I had never thought about it in a systemic way where biological life affects the geology of the planet. To me, it was particularly interesting to think about, say, plastic waste as a shift in the biogeochemical cycle and not as an alien waste product.
posted by Eyebrows McGee at 9:03 PM on May 25, 2017 [1 favorite]

"[Plastic] could be the only reason the earth allowed us to be spawned from it in the first place. It wanted plastic for itself. Didn't know how to make it. Needed us. Could be the answer to our age-old egocentric philosophical question, 'Why are we here?'"
-- George Carlin
posted by Greg_Ace at 9:16 PM on May 25, 2017 [3 favorites]

I'm fucking exhausted or else I'd go into paragraphs long description, rebent, as biogeochemical cycles of the past are actually my specialty. But basically she's talking about how a chemical substance like nitrogen or carbon move through earth's various processes like erosion or in/out of the atmosphere and also through living organisms. Nitrogen is a great example - while the atmosphere is ~78% nitrogen it's unusable in that form (N2) by plants, so it needs to be changed into another form, or "fixed" for plants to use it. This may happen through lightning and bacterial processes. Or think about when a plant dies or gets eaten - where does the nitrogen go then? Into another organism or back into the soil. Or nitrogen may enter oceans through run-off, which affects plankton populations. Humans have fucked with the nitrogen cycle in a really big way as we are now introducing about 30% of "fixed" nitrogen that exists. (BUT it's not just black and white as it's part of our agricultural processes and thus has had implications on who eats.)

So think about a rock eroding into its various elements - silica, for example - and how that might go into a river and then into the ocean, where organisms like diatoms will use it. Or how much carbon is held in the great chalks and carbonate platforms of the world like the Bahamas or Florida, which means various elements were taken out of the ocean and fixed "in place" by biological organisms like plankton or as a product of certain algae, which then in turn become rock. Later the chalk erodes back into the ocean or into a river, "releasing" the carbon, which modern plankton may use. . . . so how would a dam, or say, a series of dams on the Missouri, might impact that?

A great example of a change in biogeochemical processes in the past is the evolution of certain plants during the Oligocene, particularly grasses, that processed carbon differently in photosynthesis as a result of climate at that time - particularly low atmospheric CO2 levels and increasing acidification. As a result these grasses vastly affected global carbon storage, the carbon cycle itself, and the evolution of herbivores. (If you're interested look up evolution of C4 plants.)

This is all very very very simplified. IMHO biogeochemical cycles are some of the hardest "scienc-ing" that exist. It's a closed system with sooooo many factors - like tectonics! Are there a lot of volcanoes? Are the earth's continents lumped together or spread out? Or something like is there a Gulf Stream? Or the tilt of the earth's pole! Or - and this is huge - what organisms exist at a time.

For a fun thought experiment (one of my favorites), ponder how the earth was before the evolution of plants - besides bacterial mats there wasn't anything to keep dirt and soil from eroding away in wind and rain. What massive erosion rates! How dusty the wind was! How did the introduction of all those elements and minerals affect life in the ocean? The atmosphere? The composition of soil itself from bacterial processes (what bacteria existed?) to how soil actually formed? Then ruminate about how plants changed all that, as well as the composition of the atmosphere. That was a shift in about every biogeochemical cycle that exists.

I'm tired - I hope this makes sense.
posted by barchan at 9:41 PM on May 25, 2017 [24 favorites]

I would also like to applaud that that was a complicated but not incomprehensible paper; you have to work at it a bit as a scientific layman like I am, and use a dictionary/the google, but it's quite clear and plainly explained, and taking 20 minutes to untangle the unfamiliar words is well worth the effort. I'm fairly confident I could read it to my kids with appropriate vocabulary words explained. That's an achievement, for something so dense!
posted by Eyebrows McGee at 12:00 AM on May 26, 2017 [2 favorites]

I feel a shout-out to Vladimir Ivanovich Vernadsky (The Biosphere, 1926) is required.
posted by homerica at 3:58 AM on May 26, 2017 [1 favorite]

I love writing like this that recontextualizes science in a new framework. Nothing in the paper is exactly new, but putting all these pieces together in this specific way is insightful.
posted by Nelson at 8:20 AM on May 26, 2017 [2 favorites]

Barchan, thank you! And thank you also for explaining what "fixed" meant. That's really fascinating stuff.

One of the most surprising bits of the article was the idea that, in the past, not as many minerals existed on the earth. That they appeared within geological memory, as it were. I figured that once the planet coalesced out of all that star stuff, we had all we were going to have, and it's just been entropy ever since.

But man.... limestone! Made of old bodies!

And oil!

Question about oil - we have a meme that it's dinosaur juice, that "My jeep runs on dinosaurs" etc. But my personal theory is that long ago, there was generic biomass - bacteria mats etc - that covered the entire ocean surface (and this was when the ocean covered the entire planet - another theory I made up). I imagine there was just a ton of that biomass, and that's what was compressed down into fossil fuel. Not Brontosauruses and ferns.
posted by rebent at 8:27 AM on May 26, 2017 [1 favorite]

Most oil is from plankton, which converted to kerogen when it settled on the ocean floor and there wan't enough oxygen to cause decay. You can use the chemical signatures of a hydrocarbon (called a van krevelen diagram) to figure out its source.
posted by barchan at 8:36 AM on May 26, 2017 [2 favorites]

barchan: "For a fun thought experiment (one of my favorites), ponder how the earth was before the evolution of plants..."


This reminded me of a bit of A Land, by Jacquetta Hawkes (a book I learned about on MeFi and then got as a birthday gift!) - she's trying to describe the world before plants:
The young world must have had a most ancient aspect. In our old one, so rich with experience, what could be more youthful than England in April? It has taken three thousand million years to create that youthfulness, those fierce young buds and frail eggs, greenness that seems to cry aloud, those songs in the throats of birds and hope in the heart of man. The resurrection of the spring god. The young world was without spring; it knew nothing beyond rock and water. There was the colour of open skies and of sunrise and sunset, but when the sky was overcast the landscape was sombre beyond our present comprehension. Colour had not as yet been concentrated in leaves, petals, feathers, shells. The only sounds came from the movement of water, whether of rain or streams or waves, from thunder, and from wind sweeping across rock. At long intervals this passivity was convulsed by erupting volcanoes and by the rending and falling of vast masses of rock, but silence and stillness prevailed. No one inured to the din created by our species can conceive the silence of a calm day on pre-Cambrian earth. I cannot use the word hush which perhaps best conveys the sense of a closed-in silence for it also implies a world of life that has fallen silent. This was a negative and utter quiet. For us, in addition to our own noise -- the racket of cities that must in fact penetrate the surrounding country -- and that of animals, birds and insects, there is a fine tissue of imperceptible sounds; vegetation growing, leaves and flowers moving, all the stirrings of growth and decay. Then there was nothing. Perhaps in the heart of deserts that ancient stillness may persist, yet we cannot experience it, for wherever we go we take a humming community of life with us -- ourselves.
It's a wonderful book, and I'm glad for the opportunity to share that striking passage with MeFi.

Thank you for the great comments, barchan - and thank you for this extremely interesting post, Eyebrows!
posted by kristi at 10:41 AM on May 26, 2017 [5 favorites]

Fine fpp as always, Eyebrows!
posted by saulgoodman at 8:11 PM on May 26, 2017

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