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The Molecule that Changed Everything

2025-07-25 · letter vlog · Hank · 7:49 · watch on YouTube

Topic: Science & nature · mode: Explainer · tags: self correction, self promotion, fundraising ask

Replying to John's 'At Least There Are Trees', Hank explains how trees caused the Devonian mass extinction: lignin, which almost nothing could break down, piled up in swamps; tree-released phosphorus fed algae blooms that stripped oceans of oxygen; those buried trees became coal that powered the Industrial Revolution and now climate change. Unlike trees, humans can choose to stop a second apocalypse.

What is said

The parts of the video and what is said in each (★ — how much it matters to the video).

00:00:00 — Hank agrees with John that at least there are trees, admits he fears them, and sets up the two tree apocalypses

  • ★★ Hank agrees with John that at least there are trees and loves them, since they make oxygen, maple syrup, cherries and shade, but he also fears them. (playful) — 00:00:00
  • ★★ Hank says John was right that trees caused an apocalypse; he will explain how, since he has got it wrong before, and says trees are now attempting a second one we must stop. (playful) — 00:00:21
  • ★★ Hank says over 300 million years ago there were fish in the oceans but not yet on land, yet there were trees, which arose from competition for light. — 00:00:25

00:00:37 — Lignin: a new irregular polymer that almost nothing could digest, so swamp forests piled up; Hank's old oxygen explanation was wrong

  • ★★★ Hank says trees' answer to the competition for light was lignin, an entirely new molecule that had never existed in the history of the universe. — 00:00:37
  • ★★ Hank says he studied lignin in college, so he knows more about it than the average person. — 00:00:46
  • ★★★ Hank explains that cellulose is the same chain every time, so one enzyme action breaks it into sugars, while lignin is an irregular polymer whose chain lengths and branching are random. — 00:00:51
  • ★★ Hank says this randomness makes lignin a strong, tough structure that keeps its shape and very hard to break down, since an enzyme must attack many different bonds. — 00:01:14
  • ★★ Hank says few organisms can break down lignin: termites rely on symbiotic gut bacteria and fungi, bacteria barely manage, and fungi are the only class of organisms good at it. — 00:01:35
  • ★★★ Hank says at first no living thing could break lignin down; light and oxygen eventually did, but in dark, oxygen-free swamps trees stacked up for millions of years, forest on forest. — 00:01:50
  • ★★ Hank corrects himself: he used to think the buried trees sucking oxygen from the atmosphere caused the end-Devonian mass extinction, which he knew trees caused, but that is not what happened. — 00:02:20

00:02:34 — Phosphorus from leaves fed algae blooms that stripped the oceans of oxygen; rock weathering drew down CO2; 75% of marine species died

  • ★★★ Hank says the real problem was phosphorus: trees pulled it from rocks in the soil into their leaves, and fallen leaves washed it into rivers and oceans, where phosphorus often limits life. — 00:02:36
  • ★★★ Hank says the phosphorus fed massive algae blooms; when they died and sank, microbes breaking them down consumed all the oxygen in the water. — 00:03:04
  • ★★ Hank says, noting debate, that tree roots exposed fresh rock that absorbed carbon dioxide, causing a reverse greenhouse effect and cold that probably also contributed to the Devonian extinction. (hedged) — 00:03:33

  • ★★★ Hank says entire marine ecosystems collapsed, coral reefs vanished and 75% of marine species went extinct: trees did that, the first tree apocalypse. — 00:04:02

    “That was the first tree apocalypse.”

  • ★★★ Hank stresses the extinction was not a comet or volcano but a biological process: one kind of life thriving caused an apocalypse for many others. — 00:04:08

  • ★★ Hank says the extinction ended the Devonian and began the Carboniferous, named for the carbon-rich coal those trees left behind. — 00:04:22

00:04:31 — Buried trees became Carboniferous coal that powered the Industrial Revolution; trees cannot be blamed

  • ★★ Hank says the trees fell on each other again and again, were buried, heated and pressurized, and turned into coal. — 00:04:31
  • ★★★ Hank says 300 million years later humans dug up that coal and burned it for warmth, then for steam engines, smelting iron, making fertilizer and electrifying cities. — 00:04:44
  • ★★★ Hank says the same trees that set off the Devonian apocalypse spurred the Industrial Revolution, and in a few centuries we put much of their ancient carbon back into the atmosphere. — 00:05:01
  • ★ Hank credits the trees with a little help from big-brained primates who are not big-brained enough to stop themselves. (playful) — 00:05:33
  • ★★★ Hank says trees, overachievers in every way, cannot be blamed even for two apocalypses: they have no brains and know nothing of the future or present. — 00:05:44
  • ★★★ Hank says one might think humans worse than trees because we know what we do and can't stop, or better, because at least we might stop ourselves, which trees never could. — 00:05:58

00:06:02 — Humans can stop themselves; coal is declining but not fast enough; climate change is here; we choose whether trees cause a second apocalypse

  • ★★★ Hank says coal use is finally declining: the UK, where coal largely kicked off the Industrial Revolution, no longer burns coal at all, having burned its last. — 00:06:13 · United Kingdom
  • ★★★ Hank says the decline of coal is not fast enough. — 00:06:25
  • ★★★ Asked whether we will escape the effects of climate change, Hank says no: we are experiencing them now and are past the point of no negative impacts. — 00:06:28 · climate change
  • ★★★ Hank says he does not know whether this will become a second apocalypse-level event caused by the same trees, and he does not like not knowing. (unsure) — 00:06:40
  • ★★★ Hank says we decide whether trees cause a second mass extinction or are part of the Garden of Earth; he thinks we can choose the latter, and letting trees kill everything again would be shameful. — 00:06:50 · Earth
  • ★★★ Hank says we worked with ancient trees to set off climate instability, but can work with living trees to stave it off rather than let the old trees control us: at least there are trees. — 00:07:08

00:07:27 — Sign-off and last reminder of John's At Least There Are Trees shirt, proceeds to the Nature Conservancy

  • ★★ Hank says John's At Least There Are Trees shirt is still available, probably for the last reminder, with all proceeds to the Nature Conservancy to honor their dad, who is still at it. (hedged) — 00:07:30 · Mike Green, John Green

Threads in this video

Where the stories that moved here went next

Mentioned

Central: climate change · coal · Industrial Revolution · Late Devonian extinction · lignin · phosphorus · tree

Also: People: Annie Dillard · Mike Green

Works: At Least There Are Trees shirt

Organizations: The Nature Conservancy

Concepts: algal bloom · Bacteria · carbon · carbon dioxide · Carboniferous · cellulose · coral · enzyme · Extinction event · fertilizer · fungus · greenhouse effect · microorganism · oxygen · steam engine · symbiosis · termite

Places: Earth · United Kingdom

Also centred on coal: May 30th: Ranavalona and Clean Coal · Uncomfortable Nuance: Natural Gas Edition · Trees are Destroying the Earth (Again)

Also centred on Industrial Revolution: Broadly in Favor of Humans

Also centred on Late Devonian extinction: Trees are Destroying the Earth (Again)

Also centred on tree: Nourished by Leaving · October 4, 2024 · At Least There Are Trees · I Like Being Alive

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