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An article in Nature, "Global human-made mass exceeds all living biomass" in 2020 has recently gained some attention on social media (see this Twitter thread) possibly because of a striking visualisation of the data.

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The claim, if true, is certainly striking but, I suspect, many of the numbers are based on inherently vague sources. So, despite the claim appearing originally in a prestigious journal,is it a plausible or reliable claim?

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    I'm struggling to see how this could be answered without the answer primarily comprising original research. I think all that is to be done is to understand the assumptions the paper makes which is just a matter of reading the actual paper, and checking their math which seems a bit trivial. Dec 2, 2021 at 17:31
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    When you say human made objects are you counting objects made from biomass that could still be counted as biomass after they are made?
    – Joe W
    Dec 2, 2021 at 17:34
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    After pursuing the paper, they're even counting gravel (I guess roads and foundational substrate?), so it's really no surprise it's a literally massive number. Makes one wonder when an abandoned gravel road ceases to be "a man-made object" and starts being rocks again.
    – fredsbend
    Dec 2, 2021 at 18:15
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    Plastics being lightweight, it's really far more surprising the paper claims the total mass of all plastic is double that of all animals.
    – fredsbend
    Dec 2, 2021 at 18:16
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    To make my comment more clear, the problem is that the answer is entirely based on a combination of 1) trivial math, 2) estimation, and 3) definitions of human-made/biomass. (1) isn't interesting unless there is an arithmetic error, (3) isn't really related to skeptics, anyone can operationally define these things any way they like, to interpret you just have to know how they've done it and anyone can quarrel with any choice made, it's arbitrary. (2) is similar, though you could ask a specific question about a specific estimate the title question relies on many of these rather than one claim. Dec 2, 2021 at 19:12

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