books & arts Indelible footprint

The Anthropocene: started to influence land cover significantly Thermal Maximum, a period of abrupt A New Epoch of some 10,000 years ago, when the warming about 55.5 million years ago; Geological Time? development of agricultural systems led to a and the more recent Miocene and mid- sustained growth in the human population. Pliocene warm intervals. Despite an edited by He points out that if massive amounts of extensive search, no satisfactory analogue Jan Zalasiewicz, land use were a marker of Anthropocene to the Anthropocene emerges. However, Mark Williams, onset, the period would have begun before past warm intervals provide a unique Alan Haywood the year 1800 by which time many regions, opportunity to understand processes that and Michael Ellis including Europe, were already deforested. operate during warm, high-carbon-dioxide During the past two centuries, considerable climates. This information is invaluable in use of fossil energy has led to much larger, the evaluation of climate models used for industrial-scale changes in land cover, and future projections. PHILOSOPHICAL TRANSACTIONS OF so far about two-thirds of the terrestrial This Anthropocene-themed issue THE ROYAL SOCIETY A, ROYAL SOCIETY biosphere has been transformed by human could, however, be criticized for omitting PUBLISHING: 2011. 276PP. £58.00 activity. As Ellis points out, it seems almost important issues. Although the geological certain that the scale of this transformation history of the Earth is comprehensively hat the magnitude of human impacts will persist in the geological archive. considered, including an excellent summary on the environment is comparable to The potential influence of past land of Anthropocene stratigraphy, an in- Tthat of the great forces of nature will use on climate is also briefly discussed. depth analysis of societal feedbacks to come as no surprise to most geoscientists. Palaeoclimatologist William Ruddiman changes in the environment is missing. A special issue of the Philosophical introduced a proposal for an ‘early Possible developments in the Law of the Transactions of the Royal Society argues that Anthropocene’ in 2003. He suggested that Sea, which might be triggered by formal the current period of planetary-scale human widespread deforestation and agricultural recognition the Anthropocene, and societal influence should be recognized as a separate development began about 8,000 years ago, responses are discussed. But many other geological epoch — the Anthropocene. and led to an increase in the concentration aspects, for example the overexploitation Indeed, if humanity’s imprint on the of atmospheric greenhouse gases and the of fish resources and human impacts on environment over the past two centuries prevention of the next ice age. However, the nitrogen and phosphorus cycles, are is so mighty that it will be recorded in evidence for large-scale land-use change left untouched. And an image of Jakarta’s the geological archives forever, it seems millennia ago is very fragile, and the idea skyscrapers on the issue cover is almost the logical to accept that this period of human has largely been rejected by the geological only reminder of the powerful urbanization influence is a new chapter in the geological community. Today the year 1800, the process. Furthermore, although genetic history of our planet. approximate onset of the Industrial engineering of crops may have a profound The history of the Anthropocene as Revolution, is generally regarded as the start effect on the biosphere, this emerging an idea is explored in the first chapter. of the Anthropocene. Anthropocene issue is not discussed in Nobel Prize winner Paul Crutzen is All geological epochs come to an end depth. As such, this collection of articles typically attributed with coining the term sooner or later. How long man’s imprint on could be viewed as an introduction to the Anthropocene. But the concept can be the environment will be evident is discussed topic, rather than a well-balanced overview. traced back as far as the mid-nineteenth in a chapter on anthropogenic modification Without doubt, humans have already century, when the Italian geologist and of the oceans. It is suggested that even if left their imprint on the geological record. Catholic priest Antonio Stoppani suggested anthropogenic carbon dioxide emissions Even millions of years from now a signal that the Earth, through humanity’s impact, were stopped today, a considerable fraction of pronounced warming and ocean was entering a new geological period, which of the carbon released would persist in the acidification could be visible in marine he termed the Anthropozoic era. About atmosphere for many thousands of years, sediments. Formal recognition of the half a century later, a Russian geochemist, causing long-term acidification of the Anthropocene, as proposed in this themed Vladimir Vernadsky, developed the concept oceans and lasting global warming. On these collection, would not only draw attention to of the biosphere, casting it as a geological timescales land ice could start to disappear, the scale of human impacts on the planet, envelope around the planet’s surface, with and the Greenland and West Antarctic ice but would also stress our responsibility for geochemical properties imprinted by life. sheets could melt away, causing pronounced the planet’s future. As Vernadsky wrote He further hypothesized that humans sea-level rise. Indeed, evidence for smaller almost seventy years ago on the emergence (or, more precisely, scientific thought) ice sheets in warm climates is clearly visible of the noösphere, “The future is in our would become a large-scale geological in geological records. hands. We will not let it go.” ❐ force, transforming the biosphere into Another chapter examines the extent to the noösphere — an anthropogenically which the geological past can inform us REVIEWED BY VICTOR BROVKIN transformed Earth. about the future. Warm geological periods Victor Brovkin is at the Max Planck Institute of The history of human transformation between 100 and 2.5 million years ago Meteorology, Bundesstrasse 53, 20146 Hamburg, of the terrestrial biosphere, and the are analysed, including the climate of the Germany; also a guest at the Potsdam Institute for irreversibility of these changes, is also Late Cretaceous, a warm period around Climate Impact Research, Germany. explored. Erle Ellis describes how humans 70 million years ago; the Palaeocene–Eocene e-mail: [email protected]

496 NATURE GEOSCIENCE | VOL 4 | AUGUST 2011 | www.nature.com/naturegeoscience

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