Friday, 15 February 2013

The terraformer’s tag

We are changing the Earth. Billions of humans are working hard to survive, to have a good life or to get a better life. So it should come with little surprise that these activities modify how our planet looks like. Pristine regions are getting rare and damaged local or regional ecosystems multiply.

Mediterranean scrub
Looking with a trained eye on the lovely Mediterranean landscapes and seas we discover the shaping influence of some thousand years of human work. You find Roman mines and agricultural terraces high up desert hills.  The region holds many species and has a rich nature.

Most Mediterranean forests disappeared centuries ago.  The bottom of the Mediterranean Sea is is covered with litter so that you can trawl for trash and getting paid for it (*). Freshwater is limited in the Mediterranean region, average rain fall likely to diminish further because of anthropogenic climatic change, but likelihood of flash flows will increase. Often, when travelling, we mainly appreciate the sun, Mediterranean culture and food, and we like the blue waters of the sea ignoring the sewage pipes running far out into the sea discharging often poorly treated urban waters (**).  For other regions of the globe similar considerations can be made. We life on a nice, fairly habitable planet that took billions of years to form and to evolve.

Since some decades researchers started to notice that our activity impacts on planetary ecosystems and global geochemical cycles. We are an intrinsic part of this planet, actively shaping it. Those who have doubts, may consider that each year mankind moves more material as natural erosion and rivers. Our activities have increased global erosion rates by more than tenfold. That size of global anthropogenic impact is a new and global phenomenon. Front-runners started calling to name that phenomenon "Anthropocene" [1]. These front-runners consider that a new geological epoch of planet Earth  has started, the Anthropocene, because of the impact of mankind's economic activities. But when did it start - with inset of nuclear technology, with start of industrial age, or with onset of agriculture?

What's on the terraformer's mind?

Humans are many, but only quite recently. Our numbers have triplicated within some decades of the last century and hopefully will stabilize at nine billion around 2050.

Currently seven billions people are “terraforming” planet Earth. They do that simply by means of their accumulated economic incidences, which however is causing a new “planetary phenomenon” that merits to get named. Why? It's a mind thing! A name is needed to consciously gain ownership, to acknowledge that something  is happening, to reflect about its causes and implications, and to make it part of a public debate  - thus, simply for thinking "what we should do about it".

The human mind captures a “phenomenon” by giving it a name, developing a notion. Some would say it needs a  “meme” [2] to integrate a “phenomenon” into our thinking and our culture. “Anthropocene” is the notion currently emerging in science and public debate for capturing the impact of human activity on planet Earth. The notion “Anthropocene” is coined to name the geological period in which accumulated human economic activity is getting at pair with natural planetary geological or biological processes; leaving the notion "Holocene" [3] for naming the recent geological period when first signs of human impact can be identified with onset of agriculture in the neolithic revolution

Human population 1950, 2002 and 2020 (forecast)

 It is a very bold claim, "getting at pair”; in particular for the general public and politicians. Only recently public accepted that human activity is putting so much carbon-dioxide into the global atmosphere that its concentrations rises. Many, who share that knowledge share too the insight that air-temperatures therefore rise on a global scale and that consequently the global hydrological cycle gets modified. Likewise the same people often share the view that current ecosystem patters are under threats, as well from anthropogenic climate change as from human consumption of natural resources.  But furthering that insight to the point that our human activities force an even deeper change of the planet, a change that set a new stage of the planet needing its proper name, that is a much bolder claim. We are acknowledging and accepting that claim by naming the current change of  planet Earth “Anthropocene”, and that is a value statement. As such it reflects our ethics.
Carajás Mine, Brazil/NASA Earth Observatory

Gaining the insight that we are entering into the “Anthropocene” is going beyond considering  planet Earth as a planet currently under pressure but being in far more critical stage [5].

The insight that we start the Anthropocene convenes also the message that the underpinning phenomenon - “terraforming by accumulated economic incidence of several billion people” – will be a lasting process. Several billion people will not go simply away. And therefore the terraforming will go on leading into the unknown.

The insight  that we start the Anthropocene also convenes the message that conservation of current state of our planet is very unlikely to happen, because our human pressure on the planet will not decrease, at least not within several decades. Billions of humans are working hard to survive, to live good or to live better, and that will remain. There is no means to stop them striving for a better life. Life of too many people simply is too poor. 

 When did we tag? 

We seem to be many humans, but in terms of biomass our species is only a very tiny fraction of total biomass on Earth, less than 1%. Nevertheless the share of primary production we consume, in addition to fossil resources, seems to be at least close to 25%; and that more than one to twenty-five rate scales our impact (***). Following the line of thought that we, humans are the main consumer of Earth's resources, the insight that we start the Anthropocene finally convenes the message that we humans collectively are the responsible actor on whom should be called upon. Acting in a responsible manner calls on our ethics regarding how do we position us in within the planetary environment “Earth”, as individual and as species?

We could tackle that question on philosophical grounds, as humans did this since aeons.  Our myths, religions, books and minds are full of related thoughts and opinions.  To enrich these, we should ask "since when do we set our tags boldly on planet Earth?"

Human tag
Thus we should ask, how do we identify in a sound scientific and ethically  meaningful manner the moment in time, in history, when the impact of our economic activities on global geochemical cycles and global ecosystems was not any longer small or negligible, but reached a noticeable strength.

Did we set "the Anthropocene tag" as early as the neolithic revolution when humans were inventing agriculture and clearing out forest? Then we do rename the Holocene.  Did we set "the  Anthropocene tag" at the onset of the industrial revolution at 1850-ties when we started to  rise levels of carbon dioxide in the atmosphere? What was the change of geochemical cycles nearly two centuries ago?  Do we set "the Anthropocene tag" with the first test of nuclear explosions in 1940-ties because that technology gave us the power to start the nuclear winter mimicking the effect of an asteroid impacting Earth?

Catch the tag !

Some months ago scientists, mainly earth scientists but also academics of other disciplines, discussed in public – one conference more (#)-  that planet Earth is entering into the Anthropocene. One of main subject of their debate: “ what is an appropriate marker?” It is expected that within some years a scientific consensus will have been found. To my view, this marker should tag the geological record in a non-equivocal manner. It should be, taking a fantasy vision, be found in 100 years, 100.000 years or in 100 million years in the geological record of planet Earth.

 Keele River, McKenzie Mountains, Canada
That "fantasy vision" is less academic as it may look like on first sight. It sharpens the focus for the kind of event the Anthropocene may be. The mayor events that did hit Earth are well recorded in the geological record. For example, the rise of free oxygen in the atmosphere and the ocean is recorded in mighty deposits of iron-ore. The great unconformities [4] mark cycles of  continent formation, and the Cambrian surge of marine live is preserved in many fossils.  We know also about the impact of a meteor, leaving a spike of Iridium, and the basalt flows of Deccan Traps hat marked jointly the fate of the dinosaurs and may other species. We know about the drying out of the Mediterranean Sea, the Messinian salinity crisis when the Straits of Gibraltar were closed.  We know about the years without summer after mayor volcano explosions recently such as the Tambora (1815) or a bit earlier the Toba 74.000 years ago that possibly nearly wiped out humans. As well we know of the mighty tsunami that hit the North Sea after the Storegga land slide at Norwegian continental margin. All these events leave markers in the regional and global geological record. So what if human economic activity currently leaves such a marker at global scale? Are we caught in the act to tag the globe?

It is straight geological practice to determine periods of the development of our planet by referring to the stratigraphic record as it is held, for example, in rock, ice, sediment, peat or soil. Considering that practice a way to assess whether we are entering into the Anthropocene is to seek how our human activity currently gets registered in the these records.

My favourite tag !

My favourite candidate for such a record are the sediments that currently form in the seas, be it in coastal zones for local record, in self-seas for regional records and in the deep see for a global record. Lake sediments possibly could be added as reference site for recording change, particular in deep lakes that were carved out in the last ice ages, such as Lake Geneva and other lakes at the foots of alpine mountain ranges. One should not forget neither records taken in peat, ice or soils.

What do the marine sediments gather?
  • Water molecules are reacting in a slightly different manner in the hydrological cycle depending on the oxygen isotope bound in it and get so fractionated. An increased global temperature influences these processes. The different isotope ratio as well as the related temperatures are recorded in the manner how oxygen isotopes are incorporated in shells of plankton that sink to the bottom of seas and lakes. [6]
  • The burning of coal and oil influences the ratio of the various carbon isotopes in the global atmosphere. These isotopes are reacting in a slightly different manner in biological processes and so get fractionated.  Measurements 
    Marine litter
       show for the last decades a change of carbon isotope ratio in the atmosphere. Thus carbon isotope composition of biomass shifts too. Peat, soil and many sediments will preserve biomass be it as fossils or as biological tracers. [6]
  • The pollution of the global environment by well identified substances can be measured on global scale. Many of these substance may not preserve for long time but some will do, such as lead from fuel-additives or radionuclides  from nuclear tests, from nuclear accidents or from processing of nuclear waste. These elements are characteristic and the decay products of radionuclides provide too for a clock to date the layer. [7]
  • Litter is present in all oceans and sea. It is a global problem, observed in the water column as  well at the sea bottom. The concentration of litter, such as plastic and glass, is particular high in shelf-sea regions and in coastal zones and the litter is incorporated in the marine sediments. In the same moment the hydraulic regime of many rivers is modified by human activity and their sediment load is modified too. Thus sedimentation rates in coastal plains shift. [8]
  • Bottom trawling in shelf-seas is reworking the bottom to a depth of several centimetres and large areas in may shelf-seas are touched. Massive bottom trawling, also in deeper shelf waters, happens since some decades up to the point that roughness of the sea bottom gets smoothed. Bottom trawling destroys the habitual benthic communities and the reworking of the sediments. Worms and their burrows are gone. [9]

Trace of bottom trawling [9]
Thus with a little bit of imagination, sediment layers that are formed currently around the globe have different chemical, physical and biological characteristics as in the past.  They are tagged with radionuclides and litter-fossils. The bottom trawling is a powerful process to mix the top-layer and change the benthic living there. The currently formed top sediment layer will separate sediment layers for which ratios of carbon and oxygen isotopes will be  different.

Likewise chemical and isotope markers are found in ice, peat and soil all over the globe. But sediment layers in coastal seas and shelf seas should change most prominently. There our impacts of human activity cumulate.  That is the tag of the onset of the Anthropocene!

 Ukko El'Hob


(**) Flying to Mallorca under right conditions (calm sea) you can see the outfall of Palma de Mallorca and the wast water plume rising to the surface.

(***) Figure difficult to obtain with some certainty but likely the ratio is bigger than 1 : 25

(#) R. Showstake, Scientists Debate Whether the Anthropocene Should Be a New Geological Epoch; Eos, Vol. 94(5), 2013

[1] Quote from Wikipedia (simplified): Stoermer originally coined and used the term Anthropocene from the early 1980s to refer to the impact and evidence for the impact of human activities on the planet earth. The word was not used in general culture until it was popularized in 2000 by Nobel Prize-winning atmospheric chemist Paul Crutzen and others who regard the influence of human behaviour on Earth's atmosphere in recent centuries as so significant as to constitute a new geological epoch.

[2] Quote from Wikkipedia (simplified): A meme is an idea, behaviour or style that spreads from person to person within a culture. A meme acts as a unit for carrying cultural ideas, symbols or practices, which can be transmitted from one mind to another through writing, speech, gestures, rituals or other imitable phenomena. Supporters of the concept regard memes as cultural analogues to genes in that they self-replicate, mutate and respond to selective pressures. The word meme is coined by the British evolutionary biologist Richard Dawkins as a concept for discussion of evolutionary principles in explaining the spread of ideas and cultural phenomena.  Proponents theorize that memes may evolve by natural selection in a manner analogous to that of biological evolution. Memes do this through the processes of variation, mutation, competition and inheritance, each of which influence a meme's reproductive success. Memes spread through the behaviours that they generate in their hosts. Memes that propagate less prolifically may become extinct, while others may survive, spread and (for better or for worse) mutate. Memes that replicate most effectively enjoy more success, and some may replicate effectively even when they prove to be detrimental to the welfare of their hosts.

[3]  Quote from Wikkipedia (simplified): The Holocene is a geological epoch which began at the end of the Pleistocene (around 12,000 to 11,500 years ago) and continues to the present. The Holocene also encompasses within it the growth and impacts of the human species world-wide. Human impacts of the modern era on the Earth and its ecosystems may be considered of global significance for future evolution of living species, including approximately synchronous lithospheric evidence, or more recently atmospheric evidence of human impacts. Given these, a new term Anthropocene, is specifically proposed and used informally only for the very latest part of modern history and of significant human impact.

[4]  Quote from Wikkipedia (simplified): The "great" unconformities of regional or continental scale (in both geography and chronology) are associated with the super-continent cycle, the periodic merger of all the continents into one approximately every 500 million years.  

[5] Quote from "State of the Planet Declaration" (simplified, adopted in 2012 at conference "Planet under pressure"): Research now demonstrates that the continued functioning of the Earth system as it has supported the well-being of human civilization in recent centuries is at risk. In one lifetime our increasingly interconnected and interdependent economic, social, cultural and political systems have come to place pressures on the environment that may cause fundamental changes in the Earth system and move us beyond safe natural boundaries. The defining challenge of our age is to safeguard Earth’s natural processes to ensure the well-being of civilization while eradicating poverty, reducing conflict over resources, and supporting human and ecosystem health. As consumption accelerates everywhere and world population rises, it is no longer sufficient to work towards a distant ideal of sustainable development. Global sustainability must become a foundation of society. It can and must be part of the bedrock of nation states and the fabric of societies. 

 [6] An easy to read and comprehsiv description of process and phenomenons related to fate of oxygen or carbon isotopes in geochemical cycles is found in "How to build a habitable Planet" by Ch. H: Langmuir and W. Broecker, Princton University Press 2012, pp. 718.

[7] Example of two publications about anthropogenic radionuclides in the North Sea; (1990) or (2011)

[8] Quote from abstract (simplified) "Litter on the Sea Floor Along European Coasts" (F: Galgani, Marine Pollution Bulletin, 40(6), 2000: The distribution of large marine debris were investigated on continental shelves of European Seas on the basis of 27 oceanographic cruises; different types of debris were enumerated, particularly pieces of plastic, plastic and glass bottles, metallic objects, glass, and diverse materials including fishing gear. The results showed considerable geographical variation in concentrations, which ranged from 0 to 101 000 pieces of debris per km x km; plastic (mainly bags and bottles) accounted for a very high percentage (more than 70%) of total number of debris; mostly in canyons descending from the continental slope and in the bathyal plain where high amounts were found down to more than 500 m.


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