The Anthropocene

Shanghai

Humans have had such an impact on the environment that scientists are debating whether we have entered a new geological time Epoch — The Anthropocene.

In 2002 the Nobel Prize-winning scientist Paul Crutzen used the concept of the Anthropocene to denote the ever increasing influence of humans on Earth. The word has entered the scientific literature as a vivid expression of the degree of environmental change on planet Earth caused by humans, denoting the need for a new Epoch of geological time.

These changes are sufficiently distinct and robustly established for suggestions of a Holocene–Anthropocene boundary in the recent historical past.

When is the Anthropocene?

For the Anthropocene to become a useful concept, it needs some quantification:

How might the Anthropocene be unique relative to the Holocene or the Pleistocene epochs that preceded it?
What criteria could we use to quantify when the Anthropocene began, and how might future generations of geologists recognise its signal in the rocks?
These questions are being addressed by BGS scientists within a team of global collaborators.

How have humans changed the environment?

Flint tool
Before the Industrial Revolution

The global human population was around 300 million in the year 1000 AD, 500 million at 1500 AD, and 790 million by 1750 AD (United Nations, 1999). Exploitation of resources was limited mostly to firewood and muscle power. Archaeological and fossil evidence seen in Holocene geology show how human activity increased.

Though human remains and artefacts are rare from this time, other indicators such as the presence of seeds and pollen from woodland trees and plants followed by pollen from crops shows how humans cleared large areas of woodland for agriculture. Soil was exposed to weathering in deforested regions and this is seen in pulses of sediment, which collected in valley bottoms.

Lead pollution is found in polar ice caps and peat bog deposits from Greco-Roman time onward (Dunlap et al., 1999; Paula and Geraldes, 2003 80 KB pdf). It has been argued that the early to mid-Holocene increase in atmospheric carbon dioxide from ~260–280 ppm, a factor in the climatic warmth of this interval, resulted from forest clearance by humans (Ruddiman, 2003 390 KB pdf).

Cornish Quarry
During and after the Industrial Revolution

From the beginning of the Industrial Revolution to the present day, global human population has climbed rapidly from under a billion to its current 6.5 billion, and it continues to rise. The exploitation of coal, oil, and gas in particular has enabled planet-wide industrialisation, construction, and mass transport.

Humans have caused a dramatic increase in erosion of the land surface through agriculture and construction, and also by other activities such as the damming of most major rivers. As well as these physical changes, the signal of chemical pollutants and radioactive waste that we have accumulated over the past 200 years will leave a signal that stretches into the distant future, and one which would be identified by geologists millions of years hence as identifying the Anthropocene.

All these changes to the Earth's surface have a human 'signature'.

Anthropogenic change to the upper surface of the Earth


 

BGS geological maps show artificial ground (pictured above) as made ground, worked ground, infilled ground, landscaped ground and disturbed ground.

For more detailed information, see Classification of Artificial (man-made) Ground report and DiGMapGB Artificial Ground Theme.

How is this important for climate change research?

Understanding the Anthropocene is important for climate change research because the majority of the geological time boundaries sit at fundamental changes in the Earth's climate. For example, the Eocene–Oligocene Epoch boundary is associated with the growth of the Antarctic ice sheet and the Neogene–Quaternary Period boundary is associated with the development of an intense northen hemisphere glaciation.

These changes in climate have major effects on flora and fauna at the time; those preserved as fossils show these changes. In studying the Anthropocene, we can gauge a sense of the degree of present environmental change by comparison with those changes of the geological past. This therefore allows us to measure the extent of present environmental change and compare it with the natural variability of the Earth's environment.

Contact

Contact Dr Mark Williams (Climate Change) and Simon Price (Urban Geology) for further information.