Are we now living in Anthropocene?

Are we now living in Anthropocene?
By
Adi Maulana

We probably are not quite familiar with a new term called Antrhopocene since such a term has not been used or found in our common references, encyclopaedia or dictionary in our school and house. Even among “us”, the earth scientist, this term has never been taught or discussed in our class. Nevertheless, it was not until 2004, when some scientist used this term in some paper work, did the “Anthropocene” has entered the geological literature informally, to imply the contemporary global environment which dominated by human activity. The term so called “Anthrophocene”, was initially recommended by a Noble Prize – wining chemist, Paul Grotzen in 2002. It comes from word “anthropogenic”, which refers to anything relating to or resulting from the influence that humans have on the natural world. He proposed that we had already left the Holocene and entered the new Epoch –The Anthrophocene. His idea was based on the global environmental effect of increased human population and economic development that utterly have influenced every single thing in our life.

It has been widely accepted that we are still living in Holocene epoch in geologic time. The Holocene is assumed and has been entrenched to be the latest of many quaternary interglacial phases and the only one to be accorded the status of an epoch. It is also the only unit in the Phanerozoic -the past 524 m.y- whose base is defined in term of number of years from the present. The early Holocene was a time of pronounced rise in global temperature, stabilizing at 11,000 years B.P., and sea level stabilizing at 8000 years B.P. Temperature and sea level reached a characterized stage where they have, until very recently, remained. Over the past 400,000 years, despite the fact that being altered by millennial-scale global temperature fluctuation of ~ 10 c amplitude, this climate stage represents the longest gap of stability of climate and sea level. Yet, this consistent change has been a noteworthy factor in the development of human civilization.

Nevertheless, given that the Earth has underwent a substantial change from several point of views, many scientist considered that this change sufficient to leave a global stratigraphic signature distinct from that of Holocene or of previous Pleistocene interglacial phases, including novel biotic, sedimentary and geochemical change.

Human population and exploitation of energy has shown a significant increasing since the Industrial Revolution, during the course of 1000 years ago. The global population was some 300 million in the early days of 1000, raised to 500 and 790 in 1500 and 1750, respectively (United Nation, 1999). The energy consumption was limited chiefly in firewood and muscle power. The increasing level of human influence was recorded in Holocene strata, though human remains and artefacts are mostly rare. Stratigraphic signal from the mid-part of the epoch in regions settled by humans are principally biotic (pollen of weeds and cultivars following land clearance for agriculture) along with equivocal sedimentary signals (such as sediments throbs from deforested areas). It has been argued that the early to mid-Holocene increase in atmospheric CO2 from ~ 260-280 ppm, a factor in the climatic warm, resulted by humans (Rudimann, 2003).

Global human population has rapidly changed from under a billion to its current 6.5 billion (Fig.1) from the beginning of the Industrial Revolution, and it keeps rising. The exploitation of the energy sources, particularly oil, gas, and coal has allowed planet-wide industrialization, construction, and mass transport and the succeeding changes including a wide variety of phenomena, summarised as follow.

Changes to physical sedimentation
Human activity, both directly such as agriculture and construction, and indirectly, in so many words dam projects in most major rivers for irrigation and plantation, have caused a vivid increase in erosion and denudation in the continents. That condition has exceeded the natural sediments production by an order of magnitude (Hooke, 2000; Wilkinson, 2005; Syvitsky, et al., 2005; see fig.1) and means to a distinct lithostratigraphic signal, particularly when considered laterally the preservable human artefacts (e.g. the “Made Ground” of British Geological Survey maps) related to augmented industrialization.

Carbon cycle perturbation and temperature
The rising of carbon dioxide levels are over a third higher than in pre-industrial times and at any time in the past 0.9 m.y. (IPCC, 2007; EPICA community members, 2004). Conventionally, by the end of this century these level are predicted to double (IPCC,2007). The concentrations of methane in the atmosphere have already nearly double and these changes have been considerably more rapid than those associated with glacial-interglacial transitions.
Temperature in the past century rose overall and the rate of increase speeding up in the past two decades (fig 1).

Biotic Change
Since the early of the late Pleistocene, humans have caused extinction of animal and plant species, with the vanishing of a large amount of the terrestrial megafauna (Barnosky, 2004). The accelerated extinction and biotic population declines not only occurred in land, but also spread into the shallow seas, particularly on coral reef (Bellwood et al., 2004) as well as the oceans (Baum et al., 2003; Myers and Worm, 2003). The rate of biotic change may generate a vast extinction event (Wilson, 2002) similar to those took place at the K-T boundary and elsewhere in the stratigraphic column.
The estimated temperature rise will surely cause changes in habitat beyond environmental tolerance for many taxa (Thomas et al., 2004). The consequences will be more severe than in the past glacial-interglacial transitions because, with the anthropogenic disintegration of natural ecosystem, “escape” routes are fewer.
The combination of extinctions, global species migrations (Cox, 2004), and the extensive substitution of natural vegetation with agricultural monoculture is generating a typical contemporary biostratigraphic signal. These effects are permanent, as future evolution will take place from surviving (and often anthropogenically relocated) stocks.

Ocean Change
The sea level has followed an ~ 120 m rise from the late Pleistocene. Such a slight rise in sea level have been noted over the past century and assigned to a combination of ice melt and thermal expansion of the oceans (IPCC,2007). The rate and extent of imminent sea level rise depend on a range of factors that affect snow production and ice melt ; the IPCC (2007) predicted a 0.19-0.58 m rise by 2100.
Compare to pre-Industrial Revolution oceans, surface ocean waters are now 0.1 pH units more acidic due to anthropogenic carbon release (Caldeira and Wickett, 2003), a change echoed in the stable carbon isotope composition of up to date foraminiferal test (Al-Rousan et al., 2004). The forthcoming amount of acidification, scaled to estimated future carbon emissions, its spread through the ocean water column, and its final neutralization (over many millennia) has been modelled (Barker at al., 2003). Estimated consequences will be physical (neutralization of the excess acid by dissolution of ocean-floor carbonate sediment, and for this reason creating a widespread nonsequence) and biological (hindering carbonate-secreting organisms in building their skeletons), with potentially harmful effects in both benthic (especially coral reef) and planktonic setting.

Conclusion
Sufficient evidence has emerged of stratigraphically significant change (both elapsed and imminent) for recognition of the Anthropocene- presently a vivid yet global symbol of global environment change- as a new geological epoch to be considered for formalization by international discussion. However, we still wait till this proposed metaphor has been approved by the authorized council.

This article mainly adopted from GSA Today; v.18, no.2, 2008 with some major editing.

References cited
Al-Rousan,S et al., 2004, Invasion of Anthropogenic CO2 recorded in planktonic foraminifera from the northern Gulf of Aquaba: International Journal of Earths Science, v. 93,p. 1066-1076. doi :10.1007/s00531-004-0433-4.

Barnosky,A.D., Koch,P.L., Feranec,R.S., Wing,S.L., and Shabel,A.B., 2004, Assesing the causes of Late Pleistocene extinction on the continents; Science,V. 306,p.70-75

Baum,J.K., Myers,R.A., Kehler, D.K., Worm, B., Harley,S.H., and Doherty,P.A., 2003, Collapse and conservation of shark populations in the Northwest Atlantic; Science, v. 299,p. 389-392.

Bellwood, D.R., Hughes,T.P., and Nystrom, N., 2004, Confronting the coral reef crisis; Nature,V.429,p. 827-833

Caldera ,K., and Wickett,M.E., 2003, Anthropogenic carbon and ocean pH; Nature, v.425,p.365.

EPICA (European Project for Ice Croing in Antartic) community members, 2004. Eight glacial cycles from an Antartic ice core: Nature,v.429,p.623-628.

Cox, G.W., 2004, Alien species and evolution; The evolutionary ecology of exotic plants, animals,microbes and interacting native species; Washington,D.C., Island press, 377 p.

Hooke,R.LeB., 2000, On the history of human as geomorphic agents; Geology, v.28, p. 843-846.

IPCC (Intergovernmental Panel on Climate Change), 2007, Climate Change 2007: Synthesis report. Summary for policy makers: http://www.ipcc.ch/pdf/assesment-report/ar4/ar4_syr_spm.pdf.

Myers,R.A., and Worm,B., 2003, Rapid worldwide depletion of predatory fish communities; Nature,v.423,p. 280-283

Rudimann,W.F., 2003, The anthropogenic Greenhouse Era began thousands of years ago; Climatic Change, V. 61, p. 261-269

Thomas C.D., et al., 2004, Extinction risk from climate change; Nature, v.427,p.145-148.

Wilkinson,B.H., 2005, Human as geologic agents; A deep-time perspective; Geology,v.33,0.161-164.

Wilson,E.O., 2002, The future of life; New York, Alfred A.Knopf, Random House, 256. p



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Education : Sarjana Teknik, Jurusan Geologi UNHAS
Master of Philosophy (Mphil) Student
Research School of Earths Science
Earth Material, Build # 47 D.A. Brown
The Australian National University
Canberra, ACT. Australia 0200

Institution : Geology Dept. Hasanuddin University
Organisation : - Member of Ikatan Ahli Geologi Indonesia
- Member of Himpunan Ahli Geofisika Indonesia
- Member of American Association of Petroleum Geologist (AAPG)