Posts Tagged ‘Geologic time scale’
Looking back enables us to look clearly ahead.
I struggled for a while to decide what to call this post, the first of three. Explain why in just a moment.
The post is predominantly from the hand of a professional writer who goes under the name of Gaius Publius. He is described as contributing editor on AMERICAblog from where one also learns that:
Gaius Publius is a professional writer living on the West Coast of the United States. Gaius has written in a variety of genres and styles. He’s published short stories and poetry, books on education & technology, and is currently working on two book-length projects, including one novel.
In addition to writing, Gaius has been a professional educator and currently manages a small publishing consultancy. He holds a Bachelors degree in Great Books with a side concentration in physics and math, and a Masters in English and Communication.
A web search soon comes across a blog where there is a collection of the gentleman’s works.
OK, back to the theme.
Five days ago I read an essay on Yves Smith’s Naked Capitalism blog that struck me as a fabulously bold and clear presentation of the climate crisis. The essay, written by Gaius, also derived a positive message from the boldness and clarity of the argument. I dropped Yves an email asking for permission to republish on Learning from Dogs and not only did I get a quick reply from Yves, that reply included approval for the reposting from Mr. Publius. Thank you both.
The essay was called: The climate crisis in three easy charts. However, I was uncomfortable that the word ‘crisis’ might be a turn-off in a blog post title, so opted for The story of carbon. So with that off my chest, let me go straight to the essay as it appeared on Naked Capitalism.
The Climate Crisis in Three Easy Charts
Yves here. This post is the first in a series by Gaius. It starts by looking at the larger climate picture over larger swathes of time and showing what level of temperature changes led to mass extinction events.
I’m preparing to pivot back to climate crisis, starting with some reformatting of the earlier Climate Series posts — the transition to WordPress wasn’t kind to them — and the organization of this material into book form. (There’s also a climate-themed novel in the works; thriller fans, stay tuned.)
As a result, I’m doing serious study to refine both the concepts (or rather, the explanation of them) and the dating of coming events (the crisis in its various stages).
The first part of that pivot includes two media appearances this week. I’ll be on Virtually Speaking With Jay Ackroyd this Thursday (May 2) at 9 pm ET to discuss climate crisis for a full hour, followed by a Sunday appearance with Avedon Carol as part of the Virtually Speaking Sundays weekly media panel.
It’s the climate discussion I want to focus on here, and I’d like to do it by focusing on three diagrams and a few references back to my earlier climate pieces.
Climate catastrophe will usher in a new geologic era
Long-scale earth history is divided into Eons, then Eras, then Periods. But in fact, prior to the Cambrian Period, when life on earth exploded in number and variety, earth history is the story of non-life or small single- or multi-celled life. And starting with the Cambrian period, there’s just one “eon” anyway. It’s eras and periods we care about.
So let’s start there, with the Cambrian Period and the flourishing of life on earth. Consider the chart below:
The divisions across the top are geologic periods, starting with the Cambrian (“Cm”), the period of “visible life”‘ — meaning a proliferation of hardshelled species. It’s the big explosion of life on earth. The numbers across the bottom are millions of years ago. The spikes show extinction events, with the percentage of marine species going extinct expressed on the vertical or Y axis.
The chart doesn’t call them out, but starting with the Cambrian period, we’ve had three geologic eras (the larger divisions):
The Paleozoic Era runs from the start of the graph to the big spike at 250 million years ago on the X axis. It encompasses six geologic periods and ended in the greatest mass extinction event on the planet — geologists call it the “Great Dying”.
The Mesozoic Era runs from the Great Dying at 250 million years ago to the big spike at 65 million years ago, the event that wiped out the dinosaurs — and every other large species. That cleared the way for mammals to grow big and thrive.
We’re now in the Cenozoic Era. Keep those transitions in mind — when mass extinctions change which groups of species can evolve and rule, it’s the end of an era and the start of another. Now look at the chart again. The whole chart shows 540 million years, and just three geologic eras. The next extinction event on the scale of the one at 250 million years ago, or the one at 65 million years ago, will change the shape of life on earth and usher in a new era. Ready for that?
Where does man fit in?
Great question — where does man fit in? Answer: We come in very late.
First, notice the last three geologic “periods” at the top-right in the chart above. The period marked “K” is the Cretaceous, the period at the end of the Mesozoic Era. The next period (“Pg”) is the Paleogene, the one that marks the start of the Cenozoic (new life) Era. The period after that (“N”) is the Neogene, which ended just 2 million years ago. The period after that, not shown, is the Quarternary Period, our current one.
The Neogene-Quarternary boundary is the start of the time of great glaciers, and the best way to show that is with the chart below, showing earth temperatures mapped across the geologic periods (at the left end) and geologic epochs (the rest of the chart).
First, get oriented. On the Y axis is global temperature using change — in °C — from global temperature in the year 1800 as the norm or zero mark. (The global pre–Industrial Revolution temperature is generally the mark from which other global temperatures are measured, unless otherwise noted. To convert from °C to °F, just double the number; you’ll be pretty close.)
On the X axis, the first big division — from 542 million years ago to 65 million years ago — represents the first two geologic eras, the Paleozoic and Mezozoic (which unfortunately aren’t called out on this chart). “K” at the top and bottom is still the Cretaceous Period, and the end of the Cretaceous Period is also the end of the dinos and the end of the Mesozoic Era.
In this respect, both charts are the same. Man hasn’t showed up yet — our mammal ancestors were the equivalent of field mice in that world, small prey with soft shells and hiding skills.
But before we look at the rest of the X axis, notice that in the left-most part of the chart, the Y axis shows a huge change in global temperature relative to pre-Industrial norms. Looks like a monster spike, especially the first one, doesn’t it?
The Cambrian temperature spike is 6–8°C (about 11–14°F) higher than pre-Industrial levels.
It’s also the temperature we’re headed for by 2100.
But let’s not get distracted. Let’s set some markers in this chart in the horizontal (time) dimension. The whole rest of the chart — the part after the period called “K” — shows the Cenozoic Era (“new life” or Age of Mammals). From here to the right, the chart’s subdivisions show Epochs, which are sub-parts of Periods.
[Update: For a chart that shows the relationship between eras, periods and epochs, Quarternary Period, the one we’re in, and the one we’re interested in.
The epoch of the Pleistocene, which starts the Quarternary Period (again, see the chart), is the great age of glaciers. Homo habilis evolves at this time, a little over 2 million years ago. Homo erectus evolves shortly afterward. Each starts in Africa — now you can probably guess why — and each leaves Africa and spreads across the globe. (Homo erectus, by the way, lasts a long time on this earth. Longer than us by a lot.)
Homo sapiens evolved much later, in the Pleistocene — the age of glaciers, remember — just 250 thousand years ago, almost died out in Africa, but rebuilt our numbers, then spread out of Africa like our cousins. Because that was the glacier age, we’re still hunter-gatherers like the the rest of our cousins. The big beasts of the earth are creatures like woolly mammoths and sabre-tooth tigers, and we’re all alive on a fairly frozen planet with glaciers coming and going.
At the end of the Pleistocene is another extinction event. At the same time that the last glaciers recede (see chart), the big mammoths and tigers (et al) die off. Simultaneous with a noticeable change in climate, what we call “human civilization” begins. You can see that above, around 12–10 thousand years ago as the planetary temperature stabilizes. From then until almost now, planetary temperature is pretty stable. Notice it doesn’t take much of a wobble to mark the “Little Ice Age”.
Just two more points to make in this piece and I’m done.
First the bad news
Folks, that little climb in temperature you see near the right end of the graph above is just the beginning. Remember the Cambrian spike at the left end of the graph? Take another look and note the increase — about 7°C. Now here’s Figure 21 from the Copenhagen Diagnosis, a report prepared by … oh … every single one of the world’s top climate scientists for the benefit of our world’s “leaders,” who met in 2009 to discuss how to pass the climate buck one more time:
What you see is temperatures from 500 AD to about 2000, with a number of prediction scenarios going forward. See the scenario called “A1FI”? It’s the one in red. That’s the one we’re on if we don’t stop spewing carbon. I call it the “do nothing” scenario — otherwise known as the “Keep David Koch Happy” scenario.
All you need to know? We’re on track for about +7°C — the peak temperature in the big Cambrian spike — by the year 2100.
Now the good news
Despite all this doom-and-gloom, it’s not over yet. Truly. By my calculation, we have a 5–10 year window to avoid the catastrophe. It won’t be easy — we’re past the point where any transition will be smooth — but we can make the transition and survive as a civilized species, humans in a recognizable world.
But two things are needed:
- This has to be our top priority, which means you and everyone you know has to be fully aware and in full battle gear. (For reference, it’s called “hugging the monster.”)
- It’s us vs. David Koch and all of his friends and enablers. Tackling any other enemy is tackling a dummy while the game is being played.
Educate your friends, and put a wrench into the Koch machine. How’s that not a plus?
If the Koch Bros keep getting rich, we move backward. If Barack “Hope & Change” Obama approves Keystone, we move backward. If the U.S. develops “domestic oil” resources, we move backward. For every new car (“carbon-delivery system”) sold, we move backward. People need to know this and think like this. We can stop the crisis, but only if we stop carbon. It’s that simple; and that stark.
But it’s also doable, and we’re the species that’s most equiped for “doable.” It’s what our big brains are for.
I’ll have more in the weeks and months ahead. I haven’t given up, not by a long shot. But you can’t pull out of a tail spin if you don’t admit you’re in one. Me, I think we can pull out.
So presumably if you are reading this, you have read the essay above. I hope so because while at first sight there appears to be much to take in, the story is clear, informed and powerful. You are unlikely to change the mind of a committed ‘denier’ but if there’s a little part of you that isn’t utterly clear about the risks ahead, then this essay is a fabulous opportunity to embrace clarity – and not to give up hope! Remember those words in the essay:
“By my calculation, we have a 5–10 year window to avoid the catastrophe. It won’t be easy — we’re past the point where any transition will be smooth — but we can make the transition and survive as a civilized species, humans in a recognizable world.”
We really may be on the verge of a new geological period.
Just a couple of weeks ago, on the 16th May, I wrote an article called The Anthropocene period. It was based on both a BBC radio programme and a conference called “The Anthropocene: A New Epoch of Geological Time?”
So imagine my surprise when I collected this week’s copy of The Economist from my mail-box last Saturday. The cover page boldly illustrated a lead article within, as this picture shows.
The leader is headlined, ‘Humans have changed the way the world works. Now they have to change the way they think about it, too.’ The first two paragraphs of that leader explain,
THE Earth is a big thing; if you divided it up evenly among its 7 billion inhabitants, they would get almost 1 trillion tonnes each. To think that the workings of so vast an entity could be lastingly changed by a species that has been scampering across its surface for less than 1% of 1% of its history seems, on the face of it, absurd. But it is not. Humans have become a force of nature reshaping the planet on a geological scale—but at a far-faster-than-geological speed.
A single engineering project, the Syncrude mine in the Athabasca tar sands, involves moving 30 billion tonnes of earth—twice the amount of sediment that flows down all the rivers in the world in a year. That sediment flow itself, meanwhile, is shrinking; almost 50,000 large dams have over the past half- century cut the flow by nearly a fifth. That is one reason why the Earth’s deltas, home to hundreds of millions of people, are eroding away faster than they can be replenished.
There’s also a video on The Economist website of an interview with Dr. Erle Ellis, associate professor of geography and environmental systems at the University of Maryland. That video link is here.
That Economist lead article concludes,
Recycling the planet
How frightened should people be about this? It would be odd not to be worried. The planet’s history contains many less stable and clement eras than the Holocene. Who is to say that human action might not tip the planet into new instability?
Some will want simply to put the clock back. But returning to the way things were is neither realistic nor morally tenable. A planet that could soon be supporting as many as 10 billion human beings has to work differently from the one that held 1 billion people, mostly peasants, 200 years ago. The challenge of the Anthropocene is to use human ingenuity to set things up so that the planet can accomplish its 21st-century task.
Increasing the planet’s resilience will probably involve a few dramatic changes and a lot of fiddling. An example of the former could be geoengineering. Today the copious carbon dioxide emitted to the atmosphere is left for nature to pick up, which it cannot do fast enough. Although the technologies are still nascent, the idea that humans might help remove carbon from the skies as well as put it there is a reasonable Anthropocene expectation; it wouldn’t stop climate change any time soon, but it might shorten its lease, and reduce the changes in ocean chemistry that excess carbon brings about.
More often the answer will be fiddling—finding ways to apply human muscle with the grain of nature, rather than against it, and help it in its inbuilt tendency to recycle things. Human interference in the nitrogen cycle has made far more nitrogen available to plants and animals; it has done much less to help the planet deal with all that nitrogen when they have finished with it. Instead we suffer ever more coastal “dead zones” overrun by nitrogen-fed algal blooms. Quite small things, such as smarter farming and better sewage treatment, could help a lot.
For humans to be intimately involved in many interconnected processes at a planetary scale carries huge risks. But it is possible to add to the planet’s resilience, often through simple and piecemeal actions, if they are well thought through. And one of the messages of the Anthropocene is that piecemeal actions can quickly add up to planetary change.
We are living in interesting times!
Finally, more of Dr. Ellis may be watched on the following YouTube video.
Is this a new geological age?
Before moving to the thrust of this article, let me say that of the few things that I miss now living in Arizona, British draft beer and BBC Radio 4 are top of the list. Radio 4 have long broadcast a splendid 30-minute summary of science matters under the banner of Material World. It was the broadcast on May 12th that had a very powerful except that I will present here. The programme is available to listen online. This is how the BBC wrote up the summary,
Researchers from all over the world and various disciplines gathered together in London for a conference called “The Anthropocene: A New Epoch of Geological Time?” The term “Anthropocene” was coined by Professor Paul Crutzen of the Max Planck Institute in 2002 to suggest human activity has had such an irreversible affect on our planet, that we have entered into a new geological period, influenced by humans. The conference aimed to discuss the various research projects studying the Anthropocene, as well as to discuss whether or not it should be formalised as a geological “Epoch”. What actually is the Anthropocene, why are so many disciplines researching it and what difference will it make if it is formalized? Quentin finds out from Leicester University geologist Dr. Jan Zalasiewicz, and ecologist Professor Erle Ellis from the University of Maryland, Baltimore County.
Elsewhere on the BBC website, a fuller summary of the conference was written up by Howard Falcon-Lang, Royal Holloway, University of London. I have taken the liberty of publishing that summary, minus the photographs, below, simply because it’s so important a read.
Anthropocene: Have humans created a new geological age?
By Howard Falcon-Lang Royal Holloway, University of London, 10th May 2011
Human civilisation developed in a cosy cradle.
Over the last 11,700 years – an epoch that geologists call the Holocene – climate has remained remarkably stable. This allowed humans to plan ahead, inventing agriculture, cities, communication networks and new forms of energy.
Some geologists now believe that human activity has so irrevocably altered our planet that we have entered a new geological age.
This proposed new epoch – dubbed the Anthropocene – was discussed at a major conference held at the Geological Society in London on Wednesday. Yet some experts say that defining this “human age” is much more than about understanding our place in history. Instead, our whole future may depend on it.
The term, the Anthropocene, was coined over a decade ago by Nobel Laureate chemist, Paul Crutzen. Professor Crutzen recalls: “I was at a conference where someone said something about the Holocene. I suddenly thought this was wrong. The world has changed too much. No, we are in the Anthropocene. I just made up the word on the spur of the moment. Everyone was shocked. But it seems to have stuck.”
But is Professor Crutzen correct? Has the Earth really flipped into a new geological epoch – and if so, why is this important?
Back to the beginning
Dr Jan Zalasiewicz of the University of Leicester is one of the leading proponents of the Anthropocene theory. He told BBC News: “Simply put, our planet no longer functions in the way that it once did. Atmosphere, climate, oceans, ecosystems… they’re all now operating outside Holocene norms. This strongly suggests we’ve crossed an epoch boundary.” Dr Zalasiewicz added: “There are three ideas about when the Anthropocene began. Some people think it kicked off thousands of years ago with the rise of agriculture, but really those first farmers didn’t change the planet much. Others put the boundary around 1800. That was the year that human population hit one billion and carbon dioxide started to significantly rise due to the burning of fossil fuels in the Industrial Revolution,” he explained. Dr Zalasiewicz continued, “However, the really big changes didn’t get going until the end of the Second World War – and that’s another candidate for the boundary.”
To formally define a new epoch, geologists must show how it can be recognised in the layers of mud that will eventually form rocks. As it turns out, there is enormous practical advantage in fixing 1945 as the beginning of the Anthropocene.
“1945 was the dawn of the nuclear age,” explained Dr Zalasiewicz. “Sediments deposited worldwide that year contain a tell-tale radioactive signature from the first atom bomb tests in the States”. So, thousands of years from now, geologists (if any still exist) will be able to place their finger on that very layer of mud.
Nonetheless, the choice of 1945 for start of the Anthropocene is much more than just convenient. It coincides with an event that Professor Will Steffen of the Australian National University describes as the “Great Acceleration”. Professor Steffen told the BBC: “A few years ago, I plotted graphs to track the growth of human society from 1800 to the present day. What I saw was quite unexpected – a remarkable speeding up after the Second World War”.
In that time, the human population has more than doubled to an astounding 6.9 billion. However, much more significantly, Professor Steffen believes, the global economy has increased ten-fold over the same period.
“Population growth is not the big issue here. The real problem is that we’re becoming wealthier and consuming exponentially more resources,” he explained.
This insatiable consumption has placed enormous stresses on our planet. Writing in the prestigious journal Nature, Professor Steffen and colleagues recently identified nine “life support systems” essential for human life on Earth. They warned that two of these – climate and the nitrogen cycle – are in danger of failing, while a third – biodiversity – is already in meltdown.
“One of the most worrying features of the Great Acceleration is biodiversity loss,” Professor Steffen said. “Species extinction is currently running 100 to 1000 times faster than background levels, and will increase further this century. When humans look back… the Anthropocene will probably represent one of the six biggest extinctions in our planet’s history.” This would put it on a par with the event that wiped out the dinosaurs.
But perhaps more alarming is the possibility that the pronounced global warming seen at the start of the proposed Anthropocene epoch could be irreversible. “Will climate change prove to be a short-term spike that quickly returns to normal, or are we seeing a long term move to a new stable state?” asked Professor Steffen. “That’s the million dollar question.”
If the Anthropocene does develop into a long-lived period of much warmer climate, then there may be one very small consolation: the fossil record of modern human society is likely to be preserved in amazing detail.
Dr Mike Ellis of the British Geological Survey told BBC News: “As a result of rising sea level, scientists of the future will be able to explore the relics of whole cities buried in mud”.
In New Orleans, large areas of the city are already below sea level. The disastrous combination of rising sea level and subsidence of the Mississippi Delta on which it is built suggest that it will succumb at some point in the future. Although the Intergovernmental Panel on Climate Change (IPCC) predicts less than a metre of sea level rise over the next 90 years, more than five metres of sea level rise is possible over the coming centuries as the Greenland and West Antarctic ice caps melt.
Sea level rise of this magnitude will mean that the lower storeys of buildings will be preserved intact. Such “urban strata will be a unique, widespread and easily recognisable feature of the sedimentary deposits of the human age”, Dr Ellis commented.
Geologists of the future may also hunt for other, more unusual, “markers” of the Anthropocene epoch, such as the traces of plastic packaging in sediments.
But geologists like Dr Mark Williams from the University of Leicester hold much more serious concerns: “One of the main reasons we developed the Anthropocene concept was to quantify present-day change and compare it with the geological record,” he explained. “Only when we do so, can we critically assess the pace and degree of change that we’re currently experiencing.”
Dr Williams added that while the Anthropocene has yet to run its course, “all the signs are that the human age will be a stand-out event in the 4.5 billion year history of the Earth”.
We certainly do live in interesting times!