Misconceptions, misunderstandings, and mistakes?

Before moving onto my next post about GSSA's in the Anthropocene (an extremely hot debate), I came across a paper in the Anthropocene Review by Hamilton (2015) which I couldn't resist blogging about. The paper is different from most academic articles I've read lately, with a rather opinionated, somewhat negative review of Lewis and Maslin's (2015) paper. To recap, Lewis and Maslin (2015) conclude AD 1610 and the atomic bomb spike in 1964 are the only two viable proposals for the onset of the Anthropocene, due to having GSSPs that meet geological criteria (see my last post for the criteria). Hamilton (2015) argues that the Anthropocene's inception in 1610 is not a credible suggestion, and that Lewis and Maslin are trying to find a marker where there is no real event, and consequently ignoring key events where there is no (traditional) marker. 

To briefly summarise the main argument of the paper, Hamilton proclaims that Lewis and Maslin made a fundamental error by failing to recognise that a paradigm shift has occurred, whereby the global environment has been replaced by Earth System Science. In most definitions of the Anthropocene, humans are recognised as a 'force of nature', able to modify the functioning of the Earth System, not just changing parts of ecology, or the landscape (Hamilton 2015). Hamilton, alongside other authors who also responded to Lewis and Maslin's paper (e.g. Waters et al 2015), argue the dip in CO2 of 7-10ppm is not actually proven to be caused by human activity, and is more likely to be natural variability in the Earth System. Hamilton also argues Lewis and Maslin have become too heavily preoccupied with finding a GSSP, adopting a 'spike fetish' which has unfortunately meant they have overlooked the real key concepts of the Anthropocene. 

Though this is clearly a satirical cartoon, it is interesting
to wonder what will be found millions of years
into the future to define the age of humanity... (Source)

Related to my post yesterday about GSSPs and their strict geological criteria, Hamilton goes on to conclude that traditional stratigraphy is no longer suited for making judgements about the Anthropocene. Many other, older geologic time units have been classified by assessing fossil species in rock strata, however this is NOT a method suitable for identifying changes in Earth System functioning (Hamilton 2015). Despite this, a clear datable marker is still necessary if the AWG (Anthropocene Working Group) are to persuade the ICS to formally ratify the new epoch. The difference that Hamilton outlines is that the AWG are satisfied with finding a marker that will be apparent in the future, but Lewis and Maslin are unsatisfied unless they find a suitable GSSP now. 

The Anthropocene is as much of a debate about geology, climate science, Earth System functioning and ecology, as it is about the socio-economic conceptual consequences of its proposal. Though I will discuss GSSA's more in my next post, Zalasiewicz et al (2015) recently proposed that 1945 should be the start date for the Anthropocene due to the first nuclear bomb tests in Alamogordo, New Mexico. Inevitably, the radionuclides from the blasts have created a visible layer in rock strata. The key argument Hamilton makes about this proposal, in comparison to Lewis and Maslin's assessment, is that Zalasiewicz et al (2015) understand that the marker is just that: a marker. Zalasiewicz et al recognise that the Anthropocene isn't defined by nuclear bombs, but instead by human-induced alteration of the way the Earth System functions through fossil fuel combustion and resultant climate change. The nuclear signal, does, however signify the USA's global economic dominance and the post-war 'boom years', and thus the resultant ability for Great Acceleration to take place with rapidly increasing GHGs and consequential warming (Hamilton 2015). The Alamogordo blasts simply act as a signal for geologists in millions of years to detect as the marker of the Anthropocene - an age which has much bigger and wider global socio-economic and environmental consequences than one golden spike could wholly represent.