The Anthropocene | Has earth shifted out of its Holocene state?

on July 16 1945 the first nuclear weapon was detonated on the plains of New Mexico not only did it mark a terrifying point in human history it may also have heralded an extraordinary shift in our natural world which none could have foreseen the bomb spike can be detected in layers of ice and snow on the polar icecaps it fell over land it fell into peat bogs it fell into lakes it is not the most important of the changes around the same point in time began the great acceleration a period of socio-economic growth so rapid and profound it dramatically altered the way our planet functions greenhouse gases are increasing the enormous rate temperatures rising atmospheric circulation is changing nitrogen accumulating on land and in water ocean is acidifying species of being lost the entire fabric of the planet is being made over at a very rapid rate our impact has been so extreme many scientists claim we're now living in a new geological epoch because long after we're extinct the scar of our existence will be visible in the sedimentary rocks that form the foundations of a new world as a geologist I think it did represents a very dramatic change in the nature of the materials deposited on the planet in the blink of a geological I have we entered the Anthropocene formerly we're still living in the holla scene which as geological epochs go has been extraordinarily short-lived it began around 12,000 years ago and it's characterized by an extremely stable climate ideal for us well this this particular epoch in the history of the earth is really a golden time it is the Goldilocks time in fact it's not too hot it's not too cold it's just right for human civilization to expand unfortunately of course maybe we've expanded too much it's amazingly all the way to civilizations run up during this time absolutely so this has been the time for agriculture pastoralism people done well on almost every continent except Antarctica I think we don't know how lucky we are it just could be so much worse to understand how profound it is to leave the holocene we're going on a journey back through time through the stunning Flinders Ranges these ranges are about 500 to 800 million years old this whole ocean basin was compressed and these once horizontal layers of sand and mud and lime were buckled up into giant folds and that's why today as we drive through places like brechnar wonder at all we can see the whole succession layer by layer as we drive from one end to the others we can go down through time so I knew this is the place I really love to come have a look up there that's naturel a bed geological time units are marked by changes in the strata that occur globally they represent distinct events in the Earth's history so the amazing thing about this area is that you can go up to a particular Lane you can examine it in detail and then you can go to the next one and that's actually a ticking the clock of geological time now really beautifully distinct these colors it's a change from shallower water to deeper water from a time when there were no animals to a time where you get the first animals and those changes are very important because we can then use this as a kind of a logbook in rock that you can compare with the geological record on another continent that's what makes the Flinders Ranges very important this section of the logbook chronicles the Ediacaran period which gave rise to the first multicellular life on earth exposed sections alike illustrated pages of time with detailed depictions of individuals that lived five hundred and fifty million years ago this thing called dick and Sonia cos Tata is a matte like animal this was the anterior or front end and this whole assemblage represents a sample of a sea floor community this is quite a shallow marine environment what gave rise to this explosion of life in a creek bed in brush and a gorge lies an important clue if you weren't looking for it you'd be forgiven for walking right past it but this small brass disc draws geologists from all over the world it's known as a golden spike there it is this is the golden spike spike is in the rock this is the disc with the crosshairs marking the level that is the global position for the base of the Ediacaran period and the end of the cryogenian period probably the most massive series of ice ages that the earth has ever experienced there was so much ice the period was nicknamed snowball earth large drop stones set in the darker rock beneath me our evidence huge glaciers once moved across this region and what made it transition from snowball earth to the Ediacaran what change happened to the Earth's system the argument is that volcanoes continue to exhale carbon dioxide into the atmosphere once the ice had actually melted the carbon dioxide continued to build up and warmed up the atmosphere again and it became possible for the next stage in the history of life the Golden Spike here in the Flinders is the chosen place in the world to mark that transition in the rocks when you actually have changes in the geological record often they're just local but we can demonstrate that this is truly global and it's that change that had to be marked somewhere on earth and this is the place the transition to a new geological time unit isn't always marked in rock in fact the golden spike for the start of our epoch the Holocene is in a freezer in Copenhagen it's an ice core that records the abrupt and dramatic shift in climate that took us out of the Pleistocene it's incredible to think that the rate of rise of atmospheric co2 is now around a hundred times faster than the most rapid rate during the end of the last ice age but is that enough to declare a new geological epoch humans have always made an impact on their environment like many other species think of locust swarms mouse plagues or even methane emitting bacteria what makes this period so different is our impact on the global environment has now become so large we're changing the structure and function of the Earth's system as a whole but it's all happened remarkably fast so rapid and so big in magnitude that it looks like a meteorite strike not like anything else that biology has done in the past it's fitting that I meet professor will Stephanie in our nation's capital Canberra a city that didn't even exist before 1950 even this lake is man-made there was virtually nothing here there was old parliament house a few sheep paddocks maybe one suburb and that was it will is a world leader in Earth System science a community from which the term Anthropocene meaning the new age of humans first sprung so all this has been created during the earth rocks Canberra z' population suburbs services and infrastructure have expanded dramatically in the last 60 odd years it's a phenomenon that's occurred all over the world the impact of this extraordinary growth was revealed in a long-term research project involving 50 countries it was called the International geosphere biosphere program it was the first recognition I think formally that we need to understand more than the climate on its own we need to understand the earth as a system we wanted to put all of what we learned together in some graphs and we wanted to put 12 indicators of human activity and 12 indicators of the earth system the 12 measures of human activity included primary energy use transport and tourism we looked at the obvious ones we looked at population we looked at economy GDP we looked at at large dams they charted the increasing use of water fertilizer paper and telecommunications the graphs all started at 1750 just before the Industrial Revolution kicked off and they all looked strikingly similar what AB C's shocked us and we look at them was we I expected to see a line pretty much going fairly evenly from 1750 maybe 1800 up to the present dusty of Aleutian when I saw was a very flat line from 1750 1800 1850 1900 then from about 1950 they all skyrocketed although this post-war boom period was known to historians what wasn't mine was the corresponding shift in earth system function we had the famous greenhouse gases and again they were creeping up from the Industrial Revolution for sure co2 is the one that everyone knows but we also had methane which is very important and we had nitrous oxide which people don't think about very long lived associated with nitrogen fertilizers with agriculture nitrogen cycle is hugely important I would argue almost as important as the the carbon cycle all of them were creeping up from 1750 but again you see a breakpoint around 1950 going up very sharply we looked at global surface temperature again very Wiggly but then from about 1960 or 1970 you see a sharp increase we looked at the marine fish capture again we see a sweeping up after 1950 but interestingly we see a strong plateau from about 1995 or so to 2010 you can say ah we've gotten smart and we've gotten sustainable answers no the answer is we've just fished out the planet we've fished out most of the large fishes and now going down so these are our extremely big changes in magnitude and the systems around us that are used to geologically normal rates of change Barrier Reef Southwest Tasmania the boil forests in Canada and Russia can't cope with the rates of change that are occurring now that's why we're seeing extensive bleaching wildfires in Sexson in the north and so on so what's the cause of this sudden and dramatic shift it would be easy to look at the graphs and single out a rapidly rising population but this would be a mistake what we found was the single biggest factor was actually consumption and we found that 18% of the population was driving a seventy four percent of the global consumption so even though stuff was being increasingly made in China and India it was being consumed in the OECD countries it was named the great acceleration a change so profound it's shifted the Earth's system function outside Holocene boundaries it's this that's led Earth's system scientists suggest we've entered a new geological epoch called the Anthropocene in which humans are a force to rival nature what the scientists are proposing is absolutely extraordinary it's the most astonishing event certainly in human history almost a parallel with the arrival of life on Earth because here we have a conscious force an intelligent force that could send the earth off in that direction or in that direction this is completely unprecedented the word Anthropocene has caught on appearing in popular articles and even science journals but it's not a formal geological definition and doesn't appear in the official geological time scale formally declaring a new epoch means more than just recognizing that the world has changed those changes no matter how extreme must be recorded in the surface of the earth itself right across the globe geologists in particular stratigraphy czar bureaucratic and formal and pernickety for good reason because one of the jobs they they have to do is to look after the geological time scale and the time scale is meant to be a stable common language not just between different geologists in different parts of the world but also between generations so any change that is made is made slowly and carefully and grudgingly and only if there's overwhelming evidence so for the last seven years a working group of the International Commission on stratigraphy has been assessing geological evidence for the Anthropocene existence how'd you reckon we would recognise Anthropocene well it's small isn't it so we're a group of individuals 34 in total we are experts in a whole variety fields what we're trying to do is go through evidence from the Georgia courts that could be from Lake clays or from oceans or also even things like living organisms such as corals and trees our in caves I certainly didn't have an idea as to whether the the concept would hold up geologically and firm up or whether it would simply dissolve and I kind of haze of uncertainty after some study this mid 20th century really began to stand out you know as the time of both the greatest change and also the greatest number of signals being impressed into strata now forming so we could include things like novel materials things like aluminium we've got concrete plastics as well as geo chemical signals things like LED as well from the exhausts of cars the tops of sediment cores are also full of fly ash from the burning of fossil fuels they don't degrade with time so you'll find that these particles small spherical carbon-based particles they suddenly increase very dramatically in the 1950s and it's things like temperature changes as well they have an expression in the George Boole record which can be be found bottle assemblages are also changing a traditional marker for defining new units of geological time the biological signal is is very complex the species that we keep to eat there the cows the pig the sheep the goats their chickens the domestic animals they outweigh let's say the the total weight of of wild animals on land because of the way we've bred them in a geologically very rapid time into a different shape they will actually form differently shaped fossils and that is the key element for ostrich egg refers for paleontologists with a volume of evidence behind them the Anthropocene working group came to their conclusion early this year we can now say the Holocene world has gone we are in the beginnings of a transition to something else we're also in a broad agreement to say that we feel that this happened around about mid 20th century the idea that a new geological epoch began just over 60 years ago has ruffled feathers in the geological community Jim galing understands why well the Ediacaran period in this place is made up of four kilometers of rock formations so if you were to put your finger on just one layer within the Akron that finger now represents the total thickness of the Anthropocene a geological effect is something that could be recorded for tens of millions of years not just hundreds or thousands of years I don't believe that we will one day point to a layer and say here is the record Anthropocene it's conceptual could happen that they are throw percent becomes a physical geological event but we won't be here to know about it nor will our descendants be here that's the problem from my point of view there is a difference in that we're living through it for sure but we're examining it in classically chrono stratigraphic terms so it the important thing is that the earth system is changing and that is reflected in rock strata it happens to be that humans are driving much of this change but if it was not humans driving the change the kind of change would be as profound and as important and as deserving of consideration for inclusion on the geological time scale so Chris I'm interested in this Staten Island corn is this near to the Fresh Kills landfill site yes look it's far from a done deal before they can formally submit a proposal to declare the Anthropocene the group needs to get their hands dirty it's a mixture of local roots that are at the work so far has been a review of existing publications the next phase of work is where we need to go out and actually find the evidence of this in specific sections and we need to recall the changes as they happen and show that there's a consistency in the change of those but the short timescale requires extremely high-resolution samples if you're accurate to within a few tens or hundreds of thousands of years that's usually considered to be fairly accurate in geological terms but for us to ideally were looking at things which have got annual lamination so things like cave deposits lake plays even coral reefs corals are a particularly good candidate for reference strata because they reliably lay down annual growth bands just like trees the Australian Institute of Marine Science in Townsville boasts the largest collection of coral cores in the world it contains hundreds of cores from coral reefs all over Australia we mostly work with a species called varieties which is a really tough coral we sort of call them tough old buggers because they'll grow in very clean waters but they'll also grow in turbid inshore waters the growth bands are hard to see with the naked eye but once x-rayed are easy to spot right so this is an x-ray of a slice from a massive Carl and what we can see is these density bands what we call them yeah we're clear or listen they are and we now know that those are annual bands so we can date each of those years so you've got these fantastic historical archives sort of I call them wreaths history books the longest call that we have at Ames probably started growing about the time of the Black Death in Europe more commonly the big corals are maybe 200 years old but that means for us we can get back prior to pre-industrial times in these cold records under an ultraviolet lamp some bands glow brightly they reveal the increasing flood years during the Anthropocene with the luminescent bands what they tell us is that the very big flood events seem to be coming more frequently and more intense than they used to be several centuries ago reconstructions of seawater temperatures from the strontium calcium ratio in the cold skeletons also show this recent acceleration in warming the reason scientists discovered coral laid down and your bands was due to a series of radioactive events that occurred just over 60 years ago that left behind a chemical signature coincidentally it's those same events that may mark the start of the Anthropocene the bomb is now at 8500 feet the best candidate for the Golden Spike probably stems from the nuclear test explosions the atmospheric test explosions the advantage of nuclear fallout particularly like plutonium is that the first appearance of these in sediments in particular is pretty rapid it's about 1952 is when you start to see a globally distributed signal and accumulates we found in the Antarctic in the North Pole and across the entire planet it will take several years to amass the evidence needed to submit a formal proposal but in the meantime this urgent need for recognition of the Anthropocene outside the geological community I don't think very many people at all can understand really what's going on first of all those sort of curves that sweep up can't go on forever it's just physically impossible they won't if we keep going at our present trajectory we will drive a single species will drive the sixth great extinction event in Earth history we need fresh water we need food we need to draw these micro systems but then there's services that stand behind that that are important a really classic one is pollination okay that's really important for food systems and yet species of bees are contracting in range some are going extinct in southeast China for example you see pictures of Chinese people crawling trees with a big stick to pollinate blooms in the trees artificially because the bees have gone the Indian monsoon okay that's a regular pattern of rainfall that allows one billion people to grow food if we change atmosphere and oceanic circulation and the atmosphere by putting aerosols pollution up there enough we can flip that off like a switch probably the people who are most ignorant of this are economists one group that does get it is actually the Defense Forces and the security people they all understand that when you fundamentally change people's ability to grow food provision themselves with fresh water and so on you're gonna have security problems Syria has just gone through in the last decade it worst drought in its recorded history before things blew up people had to start moving because people could not grow enough food to support themselves and of course when there are other tensions for political reasons and so on this is just a threat multiplier as the security people talk about just to prevent temperatures rising more than two degrees a target most countries have signed up to requires a drastic change of tack we have to leave nearly 90% of existing coal reserves in the ground we have to leave half of gas reserves in the ground about 35% of oil reserves in the ground there's no Galilee Basin no new gas no new oil and that's to have a 50/50 chance it is really the the lukewarm frog effect we don't feel the water beginning to boil around us and that's why there's so much attention being brought to there the concept of the Anthropocene I've heard perfectly rational people say what won't matter when I'm dead why are we here if things don't matter when we're dead course they do we are part of a community and that community has a right to continue the existence and continued existence in the presence of other organisms on the planet and it's possible we've got all of the expertise today to actually solve these problems we just don't always have the will you know I think it will take decades for people to understand what the Anthropocene means for humankind I mean it's a profound and ethical philosophical theological rethinking that humankind has to do the Anthropocene is exceptionally powerful it is a single word that encapsulates the problem we have and the challenge we have ahead of us

Channel: ABC Science

Views: 97,980

Keywords: ABC, ABCTV, Science, Catalyst, Geology, Anthropocene, Environment, Archeology, Climate Change, Flinders Ranges, Townsville, Pollution, Conservation, Ecology, Coral Cores, Sediment

Id: ZZ845voIiOE

Length: 28min 5sec (1685 seconds)

Published: Wed Nov 16 2016