Note — Mar 15, 2020

Climate Change Is only Half the Problem. We’re Destroying the Earth’s Layer of Life

Although the article is framed around climate change and the Earth’s layer of life, it’s more of a “biodiversity crash course in species and biomass.” A clear and enjoyable read on what species are, why they are hard to define, how many there are, of which, type, on land or water, etc. Also includes a number of lovely simple graphics. In the setting of Sentiers topics from the past, it’s also one more example highlighting how much we don’t know yet and how much knowledge itself changes and evolves.

[W]hen plants invented the phenomenon “flower” – an unprecedented sexual organ – around 140 million years ago, diversification on land went wild . The variation in flying, pollinating insects exploded. With that, the land overtook the sea for good. […]

Looking at the species distribution on Earth, animals, particularly insects, would seem the dominant life form. We would live on Planet Insect. But viewed in terms of biomass, it’s plants that have undisputed dominion. In fact, the presence of plants pretty much dwarfs all other forms of life. […]

Why is the carbon molecule so essential to life? Milo explains: “In general, you could say that two-thirds of the mass of plants or animals is water.” Half of the remaining one-third “dry” weight is carbon. Suppose you weigh 60 kilos: your dry mass is 20 kilos, and your carbon mass 10 kilos. […]

Before humans began rearing livestock, took up agriculture, and started the industrial revolution, there was probably twice (!) as much biomass: an estimated 1,000 gigatonnes of carbon trapped in living matter. Milo says: “In the last thousand years there has been a strong decrease in biomass, caused by humans. Without a doubt. “