Thursday 26 March 2015

The beginning and the end of the Anthropocene

Is there an Anthropocene? This question is being debated currently and a report is to be published in 2016 on whether a geological epoch created by the transformative activities of Homo sapiens should be defined, and what should mark its beginning. According to Richard Monastersky [1]:

A committee of researchers is currently hashing out whether to codify the Anthropocene as a formal geological unit, and when to define its starting point.. .. The push to formalize the Anthropocene upsets some stratigraphers.. ..One major question is whether there really are significant records of the Anthropocene in global stratigraphy.. ..Some researchers argue that it is too soon to make a decision – it will take centuries or longer to know what lasting impact humans are having on the planet.

Monastersky then quotes from Erle Ellis, a Geographer at the University of Maryland:

"We should set a time, perhaps 1000 years from now, in which we would officially investigate this.. ..Making a decision before then would be premature."

Discussion about the Anthropocene thus reflects a typical debate among scientists and other academics having different views of what marks a definable stratigraphic boundary.

As Monastersky points out, markers could be from the Industrial Revolution, or from the radioisotope signatures resulting from atmospheric testing of nuclear weapons that ceased in the 1960s. While supporting the case for 1964 as the beginning of the Anthropocene, Lewis and Maslin [2] also put forward a strong argument for using the measurable decrease in atmospheric carbon dioxide between 1570 and 1620 (with a minimum in 1610), something that they relate to the effects of New World colonisation and dramatic changes in human population density, changes in diet and agricultural practices brought by new foods, and the development of increased trade based on industrial production. Their selection of 1610 adds another part to the Anthropocene debate, but their paper also contains an interesting review of human impacts in the very short time that Homo sapiens has been the dominant species on the Earth.

In conclusion, Lewis and Maslin write [2]:

Past scientific discoveries have tended to shift perceptions away from a view of humanity as occupying the centre of the Universe. In 1543 Copernicus's observation of the Earth revolving around the Sun demonstrated that this is not the case. The implications of Darwin's 1859 discoveries then established that Homo sapiens is simply part of the tree of life with no special origin. Adopting the Anthropocene may reverse this trend by asserting that humans are not passive observers of Earth's functioning. To a large extent the future of the only place where life is known to exist is being determined by the actions of humans. Yet, the power that humans wield is unlike any other force of nature, because it is reflexive and therefore can be used, withdrawn or modified. More widespread recognition that human actions are driving far-reaching changes to the life-supporting infrastructure of Earth may well have increasing philosophical, social, economic and political implications over the coming decades.

Whether the Anthropocene should be defined, and what its definition should be, seem trifling issues compared with those raised in that last paragraph. Whether the Anthropocene began in 1610 or 1964, it has the potential to be one of the shortest epochs thus far. The end of a geological time period is usually marked by large-scale events such as asteroid impacts, widespread upheavals in the Earth’s crust, or dramatic changes in climate. We don’t know how the Anthropocene will end and it may be from one of these causes and thus be outside human control. Alternatively, the epoch may end as a direct result of human actions. We know how destructive we have already been, and continue to be; with wars, global warming, widespread removal of forests, extinction of populations, introduction of poisons and antibiotics, etc. all being major impacts. There are those who feel that we should be able to overcome the many difficulties we face using technological solutions but, while I admire human invention, I do not feel optimistic about the future. The dominant economic system is based on growth and growth cannot be sustained indefinitely, so those of us in the Developed World will no longer be able to cocoon ourselves in warmed (or cooled) buildings and we may need to hunt and forage to obtain food. The social crises that result from a catastrophic fall in living standards can be imagined.

This is preachy, but our way of life, and its characteristic complacency, is highly damaging for other organisms on Earth and, like all the others, our epoch will end. The Anthropocene will be followed by another epoch, but what organisms will dominate? After our controlling influence is no longer present, the environment will again be the main vehicle for selection of changes in genes (a natural mechanism that we override). Bacteria and other unicellular organisms are sure to survive the cataclysmic events at the end of the Anthropocene, but what about other organisms? Will evolution result inevitably in a dominant form that makes drastic changes to its surroundings, or will there be a less destructive solution to the relationship between organisms and their environment?

[1] Richard Monastersky (2015) The human age. Nature 519: 144-147.

[2] Simon L. Lewis and Mark A. Maslin (2015) Defining the Anthropocene. Nature 519: 171-180.

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