EARTH: the biography, by the BBC

Last week, I watched the BBC/National Geographic series “EARTH: The Biography,” hosted by Iain Stewart.

Stewart is a charismatic host, with a thick Scottish accent that cannot disguise his enthusiasm for geology. The five episodes focus on: volcanoes, ice, oceans, atmosphere, and “rare planet.” Overall, I thought the series did an good job covering some of the greatest stories in geology with an emphasis on presenting the latest ideas. Snowball Earth gets screen time, for instance, and the ocean-anoxia hypothesis for the end-Permian extinction, too. They also cover ocean acidification, a topic I feel deserves wider press.

The series is well-produced. Stewart zips all around the globe, and the editors seamlessly incorporate imagery from other BBC series (like Planet Earth) as supporting content where appropriate.

Here are some of the tidbits I gleaned from the show:

Two billion tonnes of the Andes are carried down the Amazon every year (in the form of sediment weathered and eroded off the Andes). Along similar lines, 40 million tonnes of dust from the Sahara Desert are dumped on the Amazon Basin every year. I wonder if the Sahara dust is included in their sediment volume estimates, or whether it is deducted since it’s not of Andean origin. Great statistics regardless.

They tell the story of Joesph Kittenger in the atmosphere episode. He did a skydiving jump from 90 miles up! After free-falling through almost the entire Earth’s atmosphere, this crazy dude lights up a cigarette! Those were the days.

Four million tonnes of the Sun’s mass are converted into energy every second. Whoa.

Humans now move more rock and soil than all natural processes combined. Ergo: Anthropocene.

The Mediterranean Sea loses three times as much water to evaporation than it gains from rivers and rain. Without the Straits of Gibraltar to let in Atlantic water, it will dry up (and it has dried up, multiple times in the past). In illustrating this, Stewart goes into a salt mine beneath Sicily and shows some BEAUTIFUL contorted salt laminae. Worth watching the whole series just for those gorgeous patterns. (here’s one shot)

The footage of Fayetteville Green Lake in New York is excellent — this is a deep lake with pronounced internal stratification of water and not much mixing — the deep parts of the lake have become anoxic and euxinic (enriched in H₂S). They illustrate this by diving into it and the water turns PINK. It is presented, of course, as an analogy for one of the leading models for the end-Permian extinction: global ocean euxinia. It is astonishing to see pink water, and enticing to think about, but the show commits a major “fail” when they don’t tell what this substance is, or where it comes from. They describe the water as having “something deadly” in it, and then say it’s a “highly toxic poison,” or “a gas as deadly as cyanide,” but never do they (a) call it hydrogen sulfide, and (b) explain that it comes from certain kinds of bacteria that thrive in low-oxygen waters. Another complaint: they don’t say when the Permian-Triassic extinction occurred, just the same old saw about it being the “greatest” extinction in Earth history, and that it occurred “before the dinosaurs.” The word “Permian” is never used.

I have some other criticisms, too…

The phrase “a blink of an eye, geologically” is used too often. Twice in the first episode alone!

They show an image of a comet moving like a badminton birdie, with the tail pointing back where the comet came from. This isn’t accurate — comet tails point away from the sun (dragged downstream by the solar wind).

At one point, when discussing the history of life on Earth, Stewart suggests that “life needs catastrophes.” I would argue that life has diversified due to catastrophes, but that catastrophes are not necessary for life to continue. In a non-catastrophic situation, life just perpetuates itself and may exhibit increasing specialization or genetic drift within the parameters available in its environment. But “needing” a catastrophe every now and again? Only if diversification of life is the goal — I take issue with this verb.

In another episode, Stewart is describing convection in the mantle, and says that “magma” is moving upwards. This is false: it is hot rock (a solid), less dense than neighboring relatively-cold rock. The “magma” idea for the Earth’s mantle is a popular misconception which Stewart is opting to elide rather than confront.

At another point, in praising the Moon, Stewart suggests that the planet Earth’s climate would have switching between freezing cold and boiling hot if it were not for the Moon’s influence. No explanation is given for this extraordinary claim. He may indeed have a chain of evidence and inference in mind when he says this, but without a robust explanation, this statement comes off as “because scientists say so”: an authoritative statement with no supporting detail which shows how science comes to a particular conclusion. Worse, he then cranks it up with the future fear factor — they go into great detail about how we have determined that the Moon is drifting further away from Earth over time, and then suggests ominously that Earth will then lose its climatic stability. So now we’ve got alarmism too, but again, no explanation of the supposed causative relationship is given.

Overall, it’s an enjoyable series, and I was pleased to have it to watch when I had the flu last week. Check it out, and let me know what you think.