Defining the Anthropocene

I’m sure by now you can’t help but wonder why there is any need to establish a new geological age. Why can’t we just stay in the Holocene? No one likes change that much… However, the Earth is changing due to human actions, and now that we’ve started it, we can’t seem to stop it.  So come, let’s explore; why is the Earth’s state so drastically different today as opposed to approximately 11,700 years ago?

Mark Maslin and Simon Lewis refer to an epoch as a ‘formal geologic unit of time’. They assert defining a new epoch, requires a global and auxiliary stratigraphical markers (e.g. rock, sediment, or glacier ice). Global markers are known as the Global Stratotype Section and Point (GSSP), and are more commonly referred to as global spikes.

Figure 1

11,700 years before present (BP), the Holocene began. Figure 1 (Maslin and Lewis, 2015), shows the factors that may indicate a new age has arrived. In graph (a), at the Pleistocene-Holocene boundary 11,700 years ago, atmospheric CO₂ reached 260 million ppm. In the formal definition and dating of the GSSP for the base of the Holocene, Walker et al., ratify the golden spike of the Holocene as the agreed compilation of  ‘deuterium excess values, accompanied by more gradual changes in ¹⁸O, dust concentration, a range of chemical species, and annual layer thickness’.

Graphs (b), (c) and (d), also show possible indications of a new age. Graph (b) shows Methane levels from the GRIP ice core reaching a trough 5,020 years ago at just above 550 ppb. Graph (c) shows a pronounced dip in atmospheric CO₂ levels, expressed in the Law Dome ice core. Graph (d) suggests the spread of artificial radionuclides produced by the atomic bombs as a golden spike. It can be seen through the analysis of annual black tree rings, which demonstrate a peak in atmospheric radiocarbon.

Now that I’ve briefly covered the stratigraphy of where the Holocene/Anthropocene debate has originated from, I would like to consider how it is characteristically different. How do we physically notice the stratigraphical changes in the world today? Ian Sample begins by helping us understand what the Holocene is.

The Holocene marked the beginning of an interglacial period, and the end of a glacial ice age, the Pleistocene. It largely refers to the onset of warmer and wetter climatic conditions, also encompassing global growth and impacts of Homo sapiens and technology. As the Holocene incorporates the effect of human activity, there is widespread debate as to whether a defined new age is necessary.

The Anthropocene however, focuses more solely on the significance of human impacts. It regards human activity as a force of nature. We now live in a world such that human activity is as natural a process as volcanic eruptions and earthquakes. It is inescapable, indispensible, and intricately critical to our way of living and the economies we depend so heavily on. An article in The Economist asserts that the Anthropocene will produce fossils containing compilations of materials, previously unseen in the geological record. The Anthropocene fossil record will thus show ‘a planetary ecosystem homogenised through domestication’. There will also be some organisms that are no longer seen, as they are now extinct, due to failure to adapt to such a human-dominated world.

I personally think there is a need to define a new age to encompass the extent to which human activity is influencing the natural foundation our world is built upon. Would you agree? Feel free to comment with your opinion!

Next post I will be looking at the disputed origins of the Anthropocene in more detail, focusing on the more human factors, which will (hopefully) provide a firm base to analyse the economic impacts of this new geological epoch. So please, stay tuned… it’s about to get very interesting!