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The Earth Shouldn't Have Oxygen

2019-08-30 · explainer · Hank · 3:59 · watch on YouTube

Topic: Science & nature · mode: Explainer · tags: self correction, timely hook

Correcting last week's claim that the Amazon makes 20% of the world's oxygen, Hank explains the carbon cycle: oxygen accumulates only because some ocean carbohydrates never get burned, so losing the Amazon would not suffocate us, but it would release a huge carbon sink.

What is said

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

00:00:00 — Retracting the fake '20% of the world's oxygen' fact; where oxygen really comes from

  • ★★★ Hank says last week (week of 19 August 2019) he repeated the claim that the Amazon rainforest produces 20% of the world's oxygen; he has deleted it from the video as a fake fact of unknown origin. — 00:00:00

    “I've since deleted it from the video because it's a fake fact.”

  • ★★★ Hank says all land plants combined produce around 25% of the world's oxygen; the rest comes from the oceans, mostly phytoplankton. — 00:00:00

00:00:29 — We would not run out of oxygen; the carbon cycle, 'burning', and ocean blooms whose carbohydrates never get burned

  • ★★★ Hank says we imagine this wrongly: if plants stopped producing oxygen we would not run out; with no photosynthesis everything would die for lack of food, but plenty of oxygen would remain. — 00:00:29
  • ★★ Hank explains that photosynthesis turns CO2 into carbohydrates and oxygen, and turning carbohydrates back into CO2 and energy consumes O2: respiration inside an organism, combustion outside; he calls both 'burning'. — 00:00:29
  • ★ Hank complains, as one of his science-communicator beefs, that no collective word covers respiration and combustion except 'oxidation', which is too broad. (playful) — 00:01:14
  • ★★★ Hank first presents the cycle as one-to-one: carbohydrates are unstable energy reservoirs, so over geological time all get burned, reabsorbing the oxygen the plant produced. — 00:01:14
  • ★★★ Hank says the exception is in the oceans: phytoplankton blooms so large that their consumers use up all local oxygen, so the carbohydrate sinks unburned, upsetting the CO2-oxygen balance; that is why he can breathe. — 00:01:53

00:02:22 — Losing the Amazon cuts oxygen production and consumption alike; CO2 is the limiting agent; fossil fuels; the Amazon as a carbon sink

  • ★★ Hank says that because burning cannot happen in some areas, a giant reservoir of oxygen has built up in the atmosphere over time. — 00:02:22
  • ★★★ Hank says if the Amazon disappeared, less oxygen would be produced but over time less would be consumed, since oxygen consumption basically happens only when plant material is burned. — 00:02:22
  • ★★ Hank says carbon dioxide, not oxygen, is the limiting agent, hence so little CO2 in the air; the carbon trapped at the ocean bottom becomes fossil fuels over geologic time. — 00:02:51
  • ★★★ Hank says burning fossil fuels measurably lowers Earth's oxygen, but only by a small share; carbon dioxide, though, is extremely low and we are well on our way to doubling it. — 00:02:51
  • ★★★ Hank says the low but doubling carbon dioxide concentration is one of the very real reasons it is a bad idea to burn rainforests. — 00:02:51
  • ★★★ Hank says the Amazon rainforest is a sink for something like 90 billion tons of carbon dioxide, a huge service we need. (hedged) — 00:02:51

00:03:41 — We won't suffocate, but the threats to the Earth's other services are just as significant; sign-off

  • ★★ Hank is glad we won't suffocate, but wishes we saw the threats to the Earth's other services as similarly significant, because they are. — 00:03:41

In the description and comments

  • ★★ The description says a balanced carbon cycle makes as much CO2 as O2, yet the atmosphere holds 209,460 ppm of oxygen and only 440 ppm of CO2, up from a recent baseline of 275. — video description
    • a number in question (doubtful): "440" — check against the recording
  • ★★ The description says the vegetative carbon sink stores far too little CO2 to affect oxygen: burning all vegetation on Earth would lower oxygen concentration by less than 1%. — video description
  • ★★ Hank says he made the video out of curiosity about why we can breathe at all, and credits a PBS NewsHour article on why the Amazon fires won't deplete Earth's oxygen for starting him on it. — video description
  • ★★ Hank says the carbon dioxide stored in living vegetation matters enormously for global warming but has no effect on our ability to breathe. — video description · climate change

Threads in this video

  • restate · How serious is climate change? — Hank says burning fossil fuels measurably lowers Earth's oxygen, but only by a small share; carbon dioxide, though, is extremely low and we are well on our way to doubling it. (00:02:51)

Mentioned

Central: Amazon rainforest · carbon cycle · oxygen · phytoplankton

Also: Organizations: Olive Garden

Concepts: carbon dioxide · carbon sink · cellular respiration · combustion · Dead zone (ecology) · ecosystem services · fossil fuel · misinformation · photosynthesis

Only in the description or credits: climate change · PBS NewsHour

Also centred on Amazon rainforest: The Amazon isn't "Burning" - It's Being Burned

Also centred on oxygen: Behind the Scenes in the Deep Sea

Replies to

  • corrects · The Amazon isn't "Burning" - It's Being Burned — “Last week I joined an extremely unexclusive club of people who said that the Amazon rainforest produces 20% of the world's oxygen. I've since deleted it from the video because it's a fake fact.”

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