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<\/a> \u2013 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\u2019s 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 \u2013 and it is still diminishing.<\/p>\n Now, the team has delved into the statistics of industrial production and mass flows of all kinds, and reconstructed the growth, from the beginning of the 20th century, of what they call \u201canthropogenic mass\u201d. This is all the things we build \u2013 houses, cars, roads, airplanes, and myriad other things. The pattern they found was strikingly different. The stuff we build totted up to something like 35 billion tonnes in the year 1900, rising to be roughly double that by the middle of the 20th century. Then, that burst of prosperity after the second world war, termed the Great Acceleration<\/a>, and our stuff increased several-fold to a little over half a trillion tonnes by the end of the century. In the past 20 years, it has doubled again, to be equivalent to, this year, the mass of all living things. In coming years, the living world will be far outweighed \u2013 threefold by 2040, they say, if current trends hold.<\/p>\n What is this stuff that we make? It is now of extraordinary, and exploding, diversity. The number of \u201ctechnospecies<\/a>\u201d now far exceeds the estimated 9 million biological species<\/a> on Earth, and counting them exceeds even the formidable calculating powers of this team. But our stuff can be broken down into ingredients, of which concrete and aggregates take a gargantuan share \u2013 about four-fifths. Then come bricks, asphalt, and metals. On this scale, plastics are a minor ingredient \u2013 and yet their mass is still greater, now, than that of all animals on Earth.<\/p>\n It\u2019s a revealing, meticulous study, and nicely clear about what the measurements include and exclude. They do not include, for instance, the rock and earth bulldozed and landscaped as foundations for our constructions, nor all of the waste rock generated in mining the ingredients: currently, nearly a third of a trillion tonnes<\/a> of such material is shifted each year. Add in the Earth material that we use and abuse in other ways, in plowing farmland, and letting sediment pile up behind dams, and humans have cumulatively used and discarded some 30 trillion tonnes<\/a> of Earth\u2019s various resources.<\/p>\n Whichever way that you cut the cake, the team\u2019s final point in its groundbreaking study hits home, and chimes with that of another recent analysis<\/a> we both worked on. Since the mid-20th century, the Earth has been set on a new, human-driven trajectory \u2013 one that is leaving the stable conditions of the Holocene Epoch, and is entering the uncertain, and rapidly changing, new world of the Anthropocene<\/a>. The weight of evidence, here, seems unarguable. This article by Jan Zalasiewicz<\/a>, Professor of Palaeobiology, University of Leicester<\/a> and Mark Williams<\/a>, Professor of Palaeobiology, University of Leicester<\/a> is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/em><\/p>\n![\"Two](\"https:\/\/images.theconversation.com\/files\/373928\/original\/file-20201209-15-1jyvw7d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip\")
<\/a>![\"A](\"https:\/\/images.theconversation.com\/files\/373923\/original\/file-20201209-17-5lett8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip\")
<\/a>![\"The](\"https:\/\/counter.theconversation.com\/content\/151721\/count.gif?distributor=republish-lightbox-basic\")
<\/p>\n