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Our effect on the earth is real: how we’re geo-engineering the planet

Posted on 16 June 2011 by John Cook

Reposted from The Conversation. This is the fourth part in a two-week series Clearing up the Climate Debate.

CLEARING UP THE CLIMATE DEBATE: Director of the Melbourne Energy Institute and Professor of Geology Mike Sandiford explores the staggering ways we influence the shape of the globe.

Aren’t we too puny to rival the great forces of nature that shape our planet?

Certainly some prominent Australian geologists sceptical of our ability to impact our climate have said as much.

But the facts show that we are fundamentally impacting planet Earth in unprecedented ways, and we’ve known about it for a century.

Measuring our impact

So what are those measures of our geological impact, and how do they compare to the natural energy and material fluxes that shape our planet?

Geologists estimate that on average about 10 billion tonnes of sediment have been moved from mountain to sea each year over geological time by rivers and glaciers.

Since the onset of agriculture, the river sediment flux has increased about threefold, to about 28 billion tonnes each year.

Let’s compare that to our own direct activities.

We mine about seven billion tonnes of coal and 2.3 billion tonnes of iron ore each year. We shift several times as much in overburden to access these resources.

Add to this the construction aggregate (2.5 billion tonnes in the USA alone), limestone for the three billion tonnes of cement made each year and other excavations for our infrastructure, and we are clearly the dominant geological agent shaping the Earth’s surface today.

While many of our excavations are local in scale, they are not always so.

In Australia natural erosion removes about 100 million tonnes of sediment each year. With our annual exports of coal and iron ore now at about 600 million tonnes, we have increased the geological erosion rate of the continent by many factors.

And in an extraordinary demonstration of our geological power, the proposed Olympic Dam open cut development plans to extract about 14 billion tonnes of rock over a 40-year period.

With peak extraction rates of about 400 million tonnes a year, it would excavate enough rock over its life to cover metropolitan Melbourne four metres deep.

That’s a lot of rock, even by geological standards.

Frustrated fliers in the eastern states will know that volcanoes vent a lot of gas and particulate matter from the interior of the Earth. Over geological time, that material is returned to the Earth through natural mineralization, but we know that it can and does impact climate.

So how do we compare?

Our best estimates place human industrial emissions of sulfur dioxide and CO? at five and 100 times natural volcanic emissions, respectively.


Think volcanoes are powerful? Our impact is much greater.

A geological litmus test

The geochemical fingerprints of human activity are everywhere.

Since the industrial revolution the added CO? now dissolved in the oceans has increased acidity by 25%. And it is changing the geological processes operating at the sea floor.

We can see traces of the lead we have mined from Broken Hill in modern sediments all around the globe – a geochemical fingerprint of Homo sapiens to be preserved for time immemorial, like the iridium anomaly that marked the end of the dinosaurs 65 million years ago.

We even make earthquakes.

The largest earthquake in Victoria in the last 30 years was the magnitude five Thomson Dam quake, induced as a direct consequence of the filling of the Thomson dam.

Induced quakes are a common occurrence when we first fill large dams, with the largest record being a magnitude six quake in India.

Anyone who has seen film of a volcano erupt or those horrific scenes of devastation from the recent Japanese earthquake and tsunami can intuitively appreciate the immense energy involved in the natural processes that shape our planet as it vents heat stored deep within its interior.

The rate heat is released from the earth – a measure of its natural “metabolic rate” – is well understood. It’s about 44 trillion watts, and reflects the average rate of energy transferred in moving all the continents, making all the mountains, the earthquakes and the volcanoes on our planet in a process we call plate tectonics.

By way of contrast, the International Energy Agency estimates our human “energy system” operates at a rate of some 16 trillion watts.

So we are already operating at one-third the rate of plate tectonics, and with our energy use doubling every 34 years we are on course to surpass plate tectonics by about 2060.

Climate scientists talk about the climate sensitivity in terms of a “radiative forcing” – an obscure term that accounts for the rate of heat energy gain or loss due to a change in a climate parameter.

The radiative forcing of a doubling of CO? is about 1300 trillion watts – or 28 times the energy released by plate tectonics.

And we are well on the way to doubling CO?. In the past hundred years we have added almost 40%, and warming that can only plausibly be attributed to a greenhouse effect is not only heating the atmosphere, but is also pumping heat into the oceans and the crust at a phenomenal rate.

When my students measure the temperature in boreholes across Australia they invariably see that almost as much heat is now going into the upper 30-50 metres of the Earth’s crust as is trying to get out – a result entirely consistent with the surface temperature rises measured by climate scientists.

Recent measurements suggest the oceans have been heating at 300 trillion watts over the last few decades.

The scale of our energy use is truly mind-boggling. In fact, the sheer size of these numbers makes it difficult for most people to grasp and comprehend their significance; few of us have any useful reference frame for comparison.


A new measure of energy use

To put these numbers into a more human context we need a a new measure for our energy use. The “Hiro” is one. It is the equivalent to the energy released by detonating one Hiroshima “Little Boy” bomb every second. One Hiro equals 60 trillion watts.

In these terms, our human energy system operates at a rate of 0.25 Hiros, or one Hiroshima bomb every four seconds. That is the equivalent of more than eight million Hiroshima bombs going off each year.

And we are on a trajectory towards the one Hiro mark by 2100, equivalent to the energy release of one bomb each year for every five-square kilometre patch of land on the planet.

The ocean heating is at 5 Hiros over the last few decades – the energy equivalent of detonating more than a 150 million Hiroshima bombs in our oceans each year.

And the radiative forcing of the CO2 we have already put in the atmosphere in the last century is a staggering 13 Hiros. The equivalent in energy terms to almost half a billion Hiroshima bombs each year.

The world’s human population has grown so much and so fast – trebling in one century and still rising by more than 70 million a year – that it’s perhaps not surprising that the vast scale of our geological impact is yet to sink in.

But it should not be a surprise because the realisation is not new.

Undercover geological agents

“Most interesting of all, perhaps, is the question whether man, by his prodigious combustion of coal … is producing more [carbon dioxide] than can be eliminated by ordinary natural processes. If this production is excessive, the result eventually may be an unwelcome change in his atmospheric surroundings."

One can imagine our shock jocks rolling their eyes at this quote, proclaiming yet more “warmist” propaganda as part of an organised climate science “swindle” hell bent on undermining the modern industrial world, or securing more government largesse.

But it only sounds like it might have been written in recent times because I have altered the wording to fit the modern context.

In reality, the author did not use “carbon dioxide”. Rather he used “carbonic acid”, a term in vogue generations ago, and a dead giveaway as to its ancestry.

And I bet our shock jocks would never guess it originates from one of the most celebrated geologists of his time.

The quote is from Arthur Woodward, “keeper of geology in the British Museum”, Fellow of the Royal Society, President of the Royal Linnean society.

Woodward’s comments appeared as preface to a classic geological text by Robert Sherlock – “Man as a geological agent” – published in 1923.

Intriguingly, Woodward’s quote followed with the suggestion that, “Man … may be approaching a stage when he should pause to consider whether his use and alteration of the crust of the earth itself are for future as well as for present advantage.”

Though he didn’t use the term, Woodward was probing the implication of man’s potential to “geo-engineer” the planet, almost 90 years ago.

WoodwardGeologists have been measuring our effect on the planet for almost a century.

An old story retold

Why was a really famous geologist writing this when human population was just one third, and CO? emissions from burning fossil fuel just 10%, of today’s rates?

For one thing Woodward was aware of the work of another giant of science – the Swedish chemist and Nobel Laureate Svante Arrhenius whose name is still part of the everyday chemistry vernacular.

Arrhenius demonstrated the greenhouse effect of CO? in 1896 estimating that a doubling of atmospheric CO? would lead to a temperature rise of 5-6°C. A few years later he settled on a 1.6°C warming, not far off the current consensus of 2-4.5°C.

The scientific basis for the CO? greenhouse effect was established over 100 years ago, before Einstein and relativity, before the Curies and radioactivity, and before Fleming and antibiotics, not to mention DNA, quantum mechanics and plate tectonics.

In fact it precedes just about everything we think of as modern science, not to mention Leninism.

In his 1923 book, Sherlock commented “Man’s work is … as worthy of a place in geological text-books as are the actions of the sea or the rivers".

The dawning of a new geological era

It would be no surprise to Sherlock or Woodward that the international geological community is now considering inaugurating a new geological epoch – named the Anthropocene – in recognition of the geological impact of our own species.

While climate sceptics are surely not alone in having a sense of disbelief in the immense scale of human activity, these figures speak for themselves.

We are indeed a geological agent of unprecedented power.

Faced with that stark reality now, it would be folly at best to maintain the fiction that we are too puny to impact the planet – at worst, it is just plain reckless.

Whether we like it or not, for better or for worse, we are already engineering our planet.

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Comments 1 to 19:

  1. The term "geo-engineering" does not apply here, as it refers to both Geo: planetary scale Engineering: Intentional intervention/"making". I.e. an unintentional side effect of our actions is not engineering. Discussion is not helped by having multiple different meanings out there for one term.
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  2. Bart In a limited semantic sense you are right. However, actions such as large scale mining are intentional in their more limited scope. And I'm not sure the term Geo can be used only for planetary scale. What would be the right term to use for an intervention that isn't intentional? Perhaps simply GeoIntervention? But certainly the sense that our interventions are planetary in scale is an important one before we get into questions of intentionality.
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  3. Thanks Mike for a thoroughly illuminating article. Its nice to know that some geologists can see what is happening.
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  4. It's sometimes said we are conducting an experiment with the Earth's atmosphere. That it is unplanned only emphasises the folly. Similarly qualifying our 'geoengineering' of the atmosphere works the same for me.
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  5. Another area where we have had a major impact is deforestation. I don't have specific numbers, but we have deforested much of Europe, North and South America. I think 'geoengineering' gets the message across.
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  6. There's an interesting article on volcano emissions compared to human emissions here. Please note that this is a pdf.
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  7. I really liked this post, thanks. In a similar vein, I thought that the visual Desdemonda Despair had up the other day was effective - Earth movement by humans and rivers.: Earth movement by humans and rivers. Maps of the United States showing, by variations in peak height, the rates at which earth is moved in gigatonnes per annum in a grid cell measuring 1° (latitude and longitude) on a side, by (A) humans and (B) rivers. Hooke (1999) / EPA Surface mining and reclamation have been identified as the dominant driver of land cover/land-use change in the central Appalachian coalfields and have produced significant changes in the region’s topography, hydrology, vegetation, groundwater, and wildlife (Townsend, et al., 2009; Loveland, et al., 2003; U.S. EPA, 2003, 2005). Coal mining in this region was identified as the greatest contributor to earth-moving activity in the United States (Hooke, 1999). I also like this graphic, which shows that for the 77 of the 92 naturally occurring elements for which we have good data, anthropogenic flows through the earth system either outright dominate (i.e. account for more than 50% of the total flows (and implying that we are responsible for MORE than 100% of the natural flows!)) or account for between 15-50% of the total flow in 54 of 77 cases. The data for that is from ELEMENTAL CYCLES: A Status Report on Human or Natural Dominance (R.J. Klee and T.E. Graedel, 2004). The graphic itself is from MIT Prof. Tim Gutowski’s lecture notes for “The Mobilization of Materials by Humans and Natural Activities”. (Warning: 45MB pdf… but some intriguing data points, visuals, etc.) (Interestingly, carbon falls into their category of "unperturbed" - which is the old chestnut that our emissions are only some small fraction of overall carbon cycling, but still significant because the "stock" nature of the accumulation over time. And I am somewhat surprised that nitrogen is considered "unperturbed". I thought that we were fixing more nitrogen than all the natural processes on land combined. Is the amount cycled in the oceans so vast that our contribution is still less than 15%?)
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  8. Thanks for that post. It was very well written. There was an article recently in the Economist on the Anthropocene that made a similar point about the magnitude of earth moved by miners and rivers:
    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.
    The Economist later added this comment about a reader's letter on the article:
    We were also pulled up over our calculation that if you divide the Earth up “evenly among its 7 billion inhabitants, they would get almost 1 trillion tonnes each”. Marek Zreda, a resident of Tucson, believes this is misleading, because “Humans inhabit the surface only. Dividing the land area (149 million square km) by the number of people (7 billion) gives about 2 hectares for each person. Take away wasteland, which amounts to roughly half of the land area, gives approximately 1 hectare per person”. Mr Zreda can easily imagine “trashing my hectare. Give me shoes, I can do it in a decade; give me a shovel, it will take a year. And give me a tractor, I will do it in a day.”
    So much for us being too puny to trash the planet.
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  9. I thoroughly enjoyed this article. Well written, informative, and a little, actually, a lot (!) worrysome! But if it's not just our emissions of C02 that's influencing the earth, then what's the solution? I mean, obviously the cause, to put it simply, is overpopulation, acheived by intelligence and, at least in part, greed. Humans have thrived since the "beginning" on the Nile delta, and especially since the industrial revolution. We are different to every other form of life on the earth, in that we have the ability to "fix" what we've done. But should we be actively reducing our population? It's a tough reality to address, but I think this whole debate comes down to just that: overpopulation.
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  10. Michael of Brisbane "I mean, obviously the cause, to put it simply, is overpopulation" I'm not so sure about that. Looking at that comment from The Economist, and at a Google Earth view of one island -Haiti/Dominican Republic - you can easily see that it's just as much about (ir)responsible stewardship of the land we happen to be on. In some places people have clearfelled then absolutely trashed the land they have. Others have ensured that the soil, water and trees in their area are healthy and the waste from their activities is properly used to improve the health of their surroundings rather than turn it into a festering open sewer or landfill. A smaller total population is desirable for a better balance in the biosphere generally. But we shouldn't pretend that we can't do better because of large numbers.
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  11. I agree wholeheartedly Adelady. It is our responsibility, and that's what I mean by saying we are unique among all life on earth. We have the responsibility and the ability to fix/manage the resources we have. But surely the more people, the more resources are required don't you think? I mean, the earth's resources are finite in that the population is increasing, as is demand on those resources, faster than the earth can recycle/replenish them.
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  12. Michael - demand on resources? Depends on which resources and how you use them. One writer got me thinking. She was referring to permaculture when she pointed out that we have all the atoms/molecules we will ever have. Fertility is not about the total number of certain molecules - it's about how often we use them in any given period of time. This of course was about composting and returning 'wastes', otherwise known as nutrients, to the soil. (And a lot of the usual arguments about letting the nutrients that disappear into the sewage system become pollution rather than useful again.) Got me thinking. Much the same can be said of all resources - and landfills. Which of course finishes right back at the idea of economics and choices. Do we quarry more rock for roadbuilding or do we find a way to reuse suitable materials from building demolition? Landfills should really be run, entirely, as sorting stations once you reframe this way. It will never be perfect. But reorganising on the basis that all materials we grow, mine, quarry or make from our natural resources are intrinsically valuable will get us a lot closer to the right balance.
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  13. Michael @ 11 I agree that high population requires high resource consumption and that resources are finite. The argument against Malthus has been that we have never run out of any resource because technological improvements have reduced the costs of extraction or that alternative technologies have removed the need for certain resources. (We can economically extract metal from ore bodies today that were deemed uneconomical to mine, say, 60 years ago. We no longer need to send out whaling fleets because whale oil has been replaces by fossil oil.) My question is how much longer will this hold true. The search for oil is taking us to deeper and deeper seabed well sites where extraction costs are very high and at the limits of our technical ability to drill. Last year's oil spill in the Texas Gulf showed us all how difficult and slow a response can be when things go wrong. Technologies have limits and in my work in the mineral extraction industry I'm not seeing any significant improvements in extraction technology. As for replacement technologies, here in Australia at least, there is precious little in the way of encouragement for research and development of sustainable energy. I sympathise with the scientists on this site. The science is sound. We have the knowledge to identify and fix the problems we face but getting the message across to the policy makers at the moment is extremely hard.
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  14. 13, Stevo,
    The argument against Malthus has been that we have never run out of any resource because technological improvements have reduced the costs of extraction or that alternative technologies have removed the need for certain resources.
    This is an interesting observation, but it fails on two counts. The first is the bulk of the world really has not been thoroughly industrialized until well after the Second World War, say for the past 50+ years. That's hardly a long enough time to claim "we've always done it before." Secondly, the world population is growing, and more importantly the percentage of the world population living an "industrialized lifestyle" is growing, even as the resources themselves are shrinking. So the demand pressures are increasing, the resources themselves are dwindling across the board, and the argument that we've always survived before is based on a mere blip in the history of human civilization. If anything, the history of human civilization shows that all civilizations ultimately crumble due to resources constraints, be it food, water, gold or something else.
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  15. The argument against Malthus also fails to take into account that we have NOT always been able to tech our way of resource limitations and thus have suffered population crashes. (Easter Is immediately springs to mind - no substitute for trees).
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  16. Spherica @14 Nicely put. Thankyou for your help. scaddenp @15 Thanks also. Easter Island is an excellent example. I'll start looking for some more.
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  17. Stevo - just look for anytime/where you had a population crash. Some of these will be disease. But others will be either resource-exhaustion or resource change (especially water). Look at ultimate causes, not proximate causes (a favourite denier tactic in many areas). Better technology has given us much improved adaptability but there is no magic in the universe which guarantees every problem is solvable, especially within a specific time frame.
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  18. scaddenp - As a historian (my qualification rather than my job) I'm on board with the concept of competition for resources being an ultimate cause of conflict. Now I just need to look for some examples of resource crises where there was no neighbouring culture available to sieze those resources from by means of warfare - pre Columbian South America looks like a good place to start. So too do the great migrations that led to the fall of the Roman Empire. Thanks again for your help.
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  19. ". She was referring to permaculture when she pointed out that we have all the atoms/molecules we will ever have.' That's an important point. The real wealth is not the number of atoms, but the way they can be used. What we need is concentrated sources of energy, in other words, negentropy. Concentrated minerals and fossil fuels are huge sources of negentropy. But they are finite, and decreasing. The only renewable source of negentropy on the Earth is solar radiation, converted in chemical negentropy by natural photosynthesis. This was the "natural" source of negentropy used by traditional civilizations. Ours is quite different - and probably with a small life expectancy given the rate at which it burns its sources of negentropy.
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