I call bullshit on this, they don't know what is all in or under the oceans.

Our constructions have now – indeed, spookily, just this year – attained the same mass as that of all living organisms on Earth. The human enterprise is growing fast, too, while nature keeps shrinking. The science-fiction scenario of an engineered planet is already here.

It seems a simple comparison, and yet is fiendishly difficult in practice. But this team has practice in dealing with such impossible challenges. A couple of years ago they worked out the first part of the equation, the mass of all life on Earth – including that of all the fish in the sea, microbes in the soil, trees on land, birds in the air and much more besides. Earth’s biosphere now weighs a little less than 1.2 trillion tonnes (of dry mass, not counting water), trees on land making up most of it. It was something like double that before humans started clearing forests – and it is still diminishing.

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