What the hell is the Anthropocene anyway?

When I was a kid, I used to drag my parents out gem/mineral/fossil hunting all the time. Possibly in revenge for all these field trips, much later my Dad threw out my mineral collection that had been stored in his garage for a decade or two while I was working overseas (Not that I'm bitter about that or anything).

Anyway, as a 12 year old I was an expert on geological eras, periods and epochs. Apparently, my childhood knowledge is now out of date (and probably mostly lost in forgotten recesses of my mind). Mike Gillings has made me aware that there is a growing scientific opinion that we are now living in a new geological epoch- the Anthropocene. As a 12 year old I would have said we were living in the Holocene Epoch, but humanity is now have such an impact on the earth, that it is likely that we would show a strong signal in the geological record from things like changes to atmospheric CO2, biodiversity loss which would show in the fossil record, changes in trace element distribution due to pollution, etc. Hence we are likely now in a new epoch- the Anthropocene (Age of Man).

When the beginning of the Anthropocene should date from is a controversial topic, but there are probably three distinct phases to the Anthropocene: the ‘paleoanthropocene’, corresponding to the widespread adoption of agriculture some 8 to 10 thousand years ago, when clearing of forests and the consequent release of greenhouse gases potentially started affecting earth systems. The second phase began in the Industrial Revolution, coinciding with significantly increased carbon emissions and the environmental degradation associated with industry. The final phase occurred post World War II, and is called “The Great Acceleration”, because it is associated with very rapid growth in human population, resource consumption, energy use and pollution.

Mike Gillings and I have just published an opinion piece (anyone who knows us knows that we're both pretty opinionated) in the journal "Anthropocene". As can be seen in Mike's beautiful figure below, we argue that the different phases of the Anthropocene has resulted in demonstrable impacts on the microbial population of the globe, including-
1. changes to the human microbiome (the community of microorganisms that live in and on the human body);
2. the evolution of bacterial metal ion and drug resistance genes (from exposure to industrial pollution and widespread clinical and agricultural use of antibiotics)
3. the dispersal of disease-causing bacterial pathogens around the globe, e.g., spread of Old World pathogens to the New World during the Age of Exploration
4. Microbiogeochemical changes on a global scale, microorganisms play a key role in the global nitrogen, carbon, phosphrous, sulfur, etc cycling, and human activities from agriculture to industry have undoubtedly affected composition of microbial communities and rates of microbial activity

Some human affects on the microbiological world