24/10/2014

The Anthropocene

Although this isn't exactly what I was planning to blog about in my second post, I thought it was too important a topic to pass up. The Anthropocene is having a moment. In fact, it is trending on social media [Figure 1]! As an environmental scientist in the making, this is hugely exciting.

Figure 1. Screen shot from my Facebook page (October 2014)

So, what exactly is the Anthropocene?

I touched on it briefly in my first post when I talked about Rockström et al.'s paper, but essentially it is the term used to describe how anthropogenic activities are altering the Earth's natural processes (i.e. biological, geological and chemical processes) so much so that they are now the driving force behind these processes.

Our impact on the planet is unquestionable. Take the go-to indicator for human-induced change: atmospheric CO2 concentration. In May 2013, CO2 levels reached 400 parts per million (ppm). Such levels have not been seen in millions of years (Jones 2013), and have certainly never been experienced by humans before. Although the Earth's climate system has undergone significant changes and seen many fluctuations over time (Zachos et al. 2001), these changes have never been as rapid as those seen in the last 200 years or so (Steffen et al. 2007).
Our impact on the planet is not only limited to climate change, but to ocean acidification, deforestation, changes to the nitrogen cycle due to our relentless use of nitrogen fertilisers, as well as species extinction (as mentioned in my first post).

The term Anthropocene was formally introduced into the literature by atmospheric chemist Paul Crutzen and biologist Eugene Stoermer in 2000 (excellent article - another must-read), although Stoermer had been using it since the 1980s (Revkin 2011). Since, the Anthropocene has been used in thousands of papers and is now widely accepted by the scientific community, with many suggesting that the term be used to delimit a new geological epoch (we are current in the Holocene, which started approximately 10-12,000 years ago).

And this is precisely why the Anthropocene is trending: the International Commission on Stratigraphy (ICS), whose role it is to define Earth's Geological Time Scale, has commissioned
a group of scientists and humanists united under the Anthropocene Working Group (AWG) to come up with "a proposal for the formal ratification of the Anthropocene as an official unit amending the Geological Time Scale". The AWG met for the first time last week in Berlin and have until 2016 to formulate the proposal and present it to the ICS for deliberation.

Exactly when the Anthropocene started is much debated. Some experts (such as Crutzen and Stoermer) maintain that it started with the Industrial Revolution (~150 years ago), while others argue that humans have been manipulating and thus impacting the planet for tens of thousands of years, notably since the advent of agriculture (Ruddiman 2013).

Regardless of when the Anthropocene actually started, it seems we can no longer ignore how big an impact we are having on the planet and its resources nowadays. I'm surprised it has taken this long for the Anthropocene to become mainstream news. But better late than never..!

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