The clue is in the carbon...

Ever heard of spheroidal carbonaceous particles (SCPs for short)? Well, unless you're really into environmental change research or atmospheric pollutants (which I hope you might be if you've stumbled across my blog), I doubt you have - and if I'm honest, neither had I until I started researching potential stratigraphic markers for the Anthropocene. SCPs are a very distinctive type of black carbon ash particle, which form only as a by-product from the incomplete high temperature (>1000°C) combustion of fossil fuels (Rose 2015; Swindles et al 2015). In other words, these are real physical carbon by-products of human activity from the burning of coal and oil. As a unique and purely anthropogenic particle, detected and preserved with high resolution in marine sediments, lake sediments, peat, and ice cores (Rose 2015), it seems SCPs could be the "golden spike" geologists and stratigraphers need to pinpoint the start of the Anthropocene!

A scanning electron microscopy (SEM)
image of an SCP. Their morphology,
shape, and colour are completely distinctive
(Source: Rose 2015) 

The presence of SCPs have been discovered synchronously on a global scale (even in remote locations such as Greenland and Antarctica), with a rapid increase in the accumulation of particles starting around the year 1950, coincidently the same time of the Great Acceleration (Rose 2015; Swindles et al 2015; Steffen et al 2007; Steffen et al 2011; Steffen et al 2015). The Great Acceleration, aka the "Atomic Age" is characterised by a signal of dramatically increasing and widespread global human impacts on the planet, e.g. increased fossil fuel combustion, rapid atmospheric CO2 increase, use of nuclear bombs, exponential growth in human population, alteration of nitrogen cycles etc (see any of the Steffen et al 2007, 2011, or 2015 papers for more detail). The stratigraphic marker chosen must characterise the nature of the Anthropocene in a range of global archives, and reflect the global pressing impact of humanity on the planet (Swindles et al 2015). Therefore it would seem SCPs, as completely non-natural markers and unambiguous signals of industrial human pollution, could be entirely suitable for an Anthropocene golden spike in the Great Acceleration (Rose 2015).

A recent study by Neil Rose (2015) represents a culmination of over two decades of research undertaken at UCL's Environmental Change Research Centre (ECRC). Rose (2015) looks at sediment cores from 71 lakes across the globe, comparing the timing and accumulation of fly ash SCPs from atmospheric deposition. Though observed start dates for the appearance of SCPs in records varies around the mid-19th century, a considerable increase is detectable in all the lakes around 1950 (Rose 2015). The increased deposition of SCPs represents the sharp rise in energy demand from post-WWII introductions of cheap fossil fuels (Rose 2015). Though deposition has generally declined in recent decades for various reasons such as cleaner fuel technologies, less heavy industry, and cleaner air legislation, the mid-20th century peak is a robust and clear signal of human impact.

Figure from Rose (2015), showing the SCP sediment profile from different lakes across the world. Solid black lines are the mean data, and the red bar is the mid-20th century mark (~1950). The rapid increase in SCPs after 1950 are clearly globally synchronous.

Why SCPs over other markers?

Other indicators of a mid-20th century Anthropocene start, such as trace metals, are prone to degradation and alteration to concentrations from changes in weathering over time (Rose 2015). A popular suggestion is the use of radionuclide fallout from nuclear weapons testing (Zalasiewicz et al 2015), however as Rose (2015) points out, half-lives of these radionuclides prevent them from being a long-term stratigraphic signal. SCPs, on the other hand, have no half-life and thus are expected to preserve well in the long-term (Rose 2015). Furthermore, SCPs are a robust signal at the same time of the Great Acceleration and are temporally close to the Alamagordo nuclear testing of 1945, unlike some proposed radionuclide fallout peaks of the early 1960s (Lewis and Maslin 2015), which occur nearly 20 years after the nuclear testing and a decade after the SCP record peak. As argued by Swindles et al (2015), radionuclides and anthropogenic soil horizons (Certini and Scalenghe 2011) fall out of favour as markers because signals can be diachronous and globally inconsistent.

Thoughts...

Though Rose's study is a fantastic piece of research into a potential marker, and illuminates the permanence of human impact in sediment records, more evidence is required from other natural archives (ice cores, peat, and marine sediments) to confirm the globally synchronous signal. It is essential that the AWG come to an agreement on a suitable GSSP or GSSA for the Anthropocene epoch's lower boundary. SCPs, with their globally synchronous, robust and crystal-clear anthropogenic signal, could be just what the group has been searching for to define the onset of the Anthropocene.

It's beginning to look a lot (un)like Christmas!

As Christmas is just around the corner, and the new year is upon us, it is natural for everyone to reflect upon the last 12 months as the year comes to a close: the good, the bad, and the ugly! For me, I can't help but wonder what the festive season will bring in the future. Say in 100, 1000, or 10,000 years time, what will we be buying one another as gifts to put under the (probably fake) Christmas tree in the Anthropocene? That's assuming we haven't deforested the entire face of the planet by then...

I stumbled across a hilarious-yet-truthful satirical post by Simon Inges and Liz Else in the New Scientist (2015), challenging readers to come up with gift ideas for the new geological epoch. The article lists some hard-hitting ideas, for example, perhaps you might buy Mum a year subscription to the 'Clean Water Company', or Dad some 'antique tinned fish' (Inges and Else 2015)? Or how about some brand new 'anti-surveillance make-up' for those awkward teenage years (Inges and Else 2015)?
And we mustn't forget the kids, none of this 'Frozen' merchandise or Lego, they'd much rather prefer a 'de-extinction kit' for all those once-loved endangered and soon-to-be-extinct species!

The kids can't believe Santa brought them a de-extinction kit for Tigers
and Elephants! (Source)

In this imagined (perhaps exaggerated) future, the 'natural world' has become a distant memory of the past, and all that remains is humanity's manufactured, artificial world. The authors of the article challenged readers to come up with their best gift ideas for this Anthropocene future, and I am still waiting to see the featured entries! Personally, I think a best-selling Christmas gift might be the 'De-polluting Clean-Air 3000', a filtering system for all the toxins and gases we can't breathe! Or maybe a 30x30cm 'Grow your own grass' patch, to remind us of the days before we urbanised every green inch of the planet. But wait, what about those essential stocking fillers: a radiation-protection gas mask for those commutes when you drive through areas of entombed nuclear waste? It sure sounds like an exciting Anthropocene Christmas! If you have more ideas, don't hesitate to post them in the comments below.

If you can't wait to see the smile of glee on Mum's face when she gets her subscription to the 'Clean Water Company', why not plan ahead a fun game to play with all the family this year? The game is called 'How to Win at the Future', created by Matheson Marcault. The CultureLab section of the New Scientist provides a great step-by-step guide of how to play this game, and, as the article says, 'Tweet like its 2099'! I won't go into the details of the game, so read the short article if you genuinely want to play, I know I will be taking this one home for Christmas! The aim of the game is to provide the funniest/most inappropriate/creative tweet in response to each scenario. The gist reminds me of 'Cards Against Humanity', but instead you use chocolate coins to represent 'likes', and the players must try to use a 'secret word' (e.g. #GameOn, or #YOLO) in their tweet which they write in response to a series of scenarios. You get more likes for the more secret words you can slip into your tweet-responses. After running through the list of scenarios (the article provides 10, but I'm sure you could make up your own), the player with the most likes wins!

One of the scenarios is quoted below:

"It’s 2155, Snow Cloud Epsilon has crashed into a space mirror, raising the prospect of the first Christmas without snow for 43 years. Is it beginning to look a lot less like Christmas?"

Now I know this given example is poking fun at geoengineering and total human fabrication of the planet, but what if the future seriously would somewhat resemble this? It would be terrifying! Another couple of favourites of mine are:

"It’s 2019. Now that he’s finally over 35, Justin Timberlake reveals his life’s ambition – to become US president. He plans to run on a global warming platform, but he has not yet chosen a running mate. Any ideas?"

And...

"It’s 2039, there’s a buzz over a new app that logs your dreams and matches you with people dreaming similar things. But you don’t even own a smarthat."

Well, here's to hoping for a smarthat for Christmas next year! Now, in all seriousness, this game could be a lot of fun if you're a bit of a sarcastic nerd like me, but there are some scary messages entwined in these ideas. Whether it be in future Christmas gifts, or in Christmas family-fun games, the state of our future is largely up to us. We can make the Anthropocene a good or a bad thing, depending on our actions in the next few decades. I only hope these joking scenarios (especially the one about space mirrors) never become reality, and that we can recognise change must happen in our behaviour and politics to prevent a frankly terrifying future epoch. As the saying goes, new year, new me, and new geological epoch with enormous societal, economic, cultural, and scientific consequences. (Yeah okay, I made that last bit up...).

Merry Christmas folks!

Bill & Fred's Excellent Adventure!

It is commonly thought that pre-industrial human societies lived in harmony with the environment (Steffen et al 2007), but evidence showing early modification of landscapes (Neolithic forest clearance, extensive use of fire, and agricultural expansion) proves this myth is just that: a myth. By now, I am sure you realise the biggest debate within the Anthropocene literature (besides whether it should even exist) is when it should begin. Defining the start date is not an easy task as it comes paired with huge implications for how we define human impact (Mackay 2015*), and there are many contrasting opinions. Cast your minds back to one of my first ever blog posts, where I summarised some key proposals for the Anthropocene start date. This post looks in detail at one of the main suggestions, the Early Anthropogenic Hypothesis (EAH) championed by William (aka Bill) Ruddiman (Ruddiman and Thompson 2001; Ruddiman 2003; Ruddiman 2007; Ruddiman 2013).

All the new agricultural expansion and livestock farming at the
dawn of the Anthropocene (according to Ruddiman),
meant our good friend Fred Flintstone could finally enjoy
some bread on his burger! (Source)

Ruddiman's EAH suggests that early agriculture in the mid-Holocene, from 8000-5000 years ago, affected the functioning of Earth Systems to such an extent the onset of a new glaciation was significantly delayed (Ruddiman 2003; see an earlier post of mine about this ice age prevention). In Ruddiman's view, the concept of the Anthropocene focuses on when humans first had a detectable global impact, but not necessarily the largest impact. There are two key facets to Ruddiman's hypothesis:

1. Increased atmospheric CO2 (carbon dioxide) concentration from forest clearance (fewer carbon sinks) particularly in Eurasia, permitting rapid expansion of agriculture 8000 years ago (Ruddiman 2003). 

2. Increased atmospheric CH4 (methane) concentration from rice cultivation in irrigated, water intensive paddy fields starting in South-East Asia 5000 years ago (Ruddiman and Thompson 2001).

Cyclic variations in methane and carbon dioxide driven by Milankovitch cycles (Earth's orbital changes of obliquity, eccentricity, and precession) over the last ~400,000 years imply a declining trend in CO2 and CH4 should have been seen throughout the Holocene. Ruddiman (2003) argues that the anomalous increases of CO2 found in Greenland ice cores 8000 years ago, and CH4 5000 years ago, show anthropogenic influence on the Earth System, whereby GHGs rose enough to prevent a new glacial inception. Ruddiman (2003) insists forest clearance and irrigation contributed to a small, yet sustained rise in global atmospheric temperatures (Mackay 2015*). 

In 2007, Ruddiman responded to a series of challenges against the original EAH (2003). Some of the updates to the hypothesis include CO2 and CH4 anomalies of 35ppm and 230ppb, respectively, which are ~90% of those proposed originally (Ruddiman 2003; 2007). Another revision to the original hypothesis was accepting that deforestation and burning of coal could only account for ~25% of the 35ppm anomaly in CO2 concentration, though Ruddiman (2007) still claims the CO2 rise is anomalous and likely to stem from human origin. Ruddiman (2007) suggests the only other likely source of the remaining 75% of the CO2 anomaly is carbon from oceans in the Holocene that did not cool like they had in earlier interglacials, thus becoming less efficient carbon sinks. Though the CH4 anomaly is largely explained by agricultural activities and climate feedbacks, the CO2 anomaly is the biggest uncertainty in his hypothesis and the reason why many academics have dismissed the credibility of his proposal.

Ruddiman's EAH: a) Anthropogenic increases in methane.
b) Anthropogenic increases in carbon dioxide.
c) Anthropogenic warming caused by GHGs.
Note the similar timing/shape of graph with warming and GHGs.
(Source: Ruddiman 2007).

Supporters of Ruddiman's EAH:

Ruddiman has received cross-disciplinary support from Dorian Fuller, an archeologist at UCL. A paper by Fuller et al (2011) concluded that wet rice paddy cultivation in Asia produces a logarithmic growth in methane emissions on a similar timeline to those posited by Ruddiman's anthropogenic methane increase. Fermentation of organic matter in these wet paddy rice fields produces significant amounts of methane (Smith and Zeder 2013). The tending of methane-emitting livestock are postulated to be another key contributor to the anomalous rise in methane, though the impacts are yet to be quantified. 

A further study by Jed Kaplan et al (2011) looked at Holocene CO2 emissions as a result of human-induced changes in land cover. The authors, which include Ruddiman, show that human residents and farmers from the late Palaeolithic to the start of industrialisation used much more land per person than any humans after them. The land-use model used by Kaplan et al (2011) has added significant weight to Ruddiman's hypothesis, as the issue with the CO2 anomaly is somewhat solved by the model, as it accounts for 24ppm rise in CO2.

Critics of Ruddiman's EAH:

Broecker and Stocker (2006) believe Ruddiman's (2003) claim that anomalous atmospheric CO2 rise 8000 years ago is anthropogenic and not natural should be examined more carefully. Ruddiman (2003) argues that without human activity, CO2 content of the atmosphere would've fallen to 240ppm instead of rising to 280ppm. Broecker and Stocker (2006) are critical of this, as huge amounts of deforestation would have needed to take place to account for a 40ppm increase in CO2. Essentially, by comparing the Holocene's orbital parameters to the early part of Marine Istope Stage 11 (MIS11), Broecker and Stocker (2006) argue that the CO2 rise over the last 8000 years stems from natural causes and not from human influence. 

Steffen et al (2007) are proponents of the Anthropocene beginning in ~1800 AD with the central feature being the exponentially growing use of fossil fuels. Steffen et al (2007) only recognise Ruddiman's EAH as a 'Pre-Anthropocene' event and not the main event, as rates of forest clearance 8000 years ago were minimal compared to deforestation in recent centuries and decades. Steffen et al (2007) argue that pre-industrial societies, though having some clear impact on the environment, did not cause changes ranging outside the normal bounds of natural variability in the Holocene, and societies could not compete with the magnitude or rate of the forces of Nature, and thus dismiss this idea as a starting date for the Anthropocene.

Thoughts and comments:

The hypothesis has sparked a large literary debate from all sorts of disciplines, having had over 50 papers published for and against Ruddiman's ideas in the last 10 years. Ultimately, this suggestion for the start of the Anthropocene between 5000-8000 years ago also has wider implications for the Holocene as we know it and creates new problems, such as whether we even need the Holocene. If the Anthropocene did begin 8000 years ago, what would be the point in the Holocene epoch existing for a mere 3,700 years? Furthermore, in 2013, Ruddiman concluded his paper stating he thinks the Anthropocene should remain an informal term, rather than applying the "simplifying" term to the "rich complexity of human history". I think this shows Ruddiman now sees the Anthropocene more as a unit of human history, than of Earth history (see my earlier post for debates on this). Ruddiman's hypothesis, though unlikely to win over the AWG for the onset of the Anthropocene, carries important messages about life on Earth today. If we were able to alter the climate and atmosphere with such little intended impact in the past, then the rate of change today (not even remotely comparable to the past) has huge implications for the future of our planet!

*Mackay, A.W. (2015) Anthropocene Epoch. International Encyclopaedia for Social and Behavioural Sciences, 2^ndEdition.

Embracing the Anthropocene...

"Instead of one Earth Day per year, there will be 364. Once a year, we’ll have an Anti-Earth-Day and allow ourselves to destroy habitats, hunt rare animals, mess with the climate and put toxins in the water. That would act as a strange reminder of the early Anthropocene."

The above quote comes from an interview in the New Scientist (2015) with Christian Schwägerl, a journalist and biologist who has recently published a book on the Anthropocene*. Schwägerl (2015) has an interesting perspective on the proposed geologic epoch, viewing it as a positive opportunity to take on a global collective responsibility in determining the future for our planet. Though recognising the concepts and arguments for the Anthropocene provides the chance to adopt a 'global stewardship' for the planet, Schwägerl (2015) also recognises the risk that I have mentioned in some earlier posts: the epoch could be taken as a way of promoting and encouraging human ownership and control over Earth Systems.

The new book by Christian Schwägerl (2014).
A very holistic and critical in-depth insight
into the Anthropocene. (Source)

How can we make the Anthropocene positive?

Firstly, it is obvious that we need to stop harbouring anthropocentric viewpoints (the belief that humans are the most significant species on Earth), and focus more on long-term goals for the future of humanity and all other life on the planet. An idea that has been toyed with in the academic literature is to market all ecosystems with a monetary value (see Costanza et al 1997). Could this be a way to encourage the conservation and protection of vulnerable and significant ecosystems in a capitalist-dominated economy?

Secondly, we must modify our social and cultural practices such that we show gratitude for our planet (Schwägerl 2015). This is where the quote at the top of this post comes into play. What if we appreciated Earth for the entire 364 days of the year, and carried out the practices we see today (hunt endangered species, pollute water sources, tear down entire rainforests, and alter the atmosphere) in just one 24-hour period? The concept is quite utopian in the current social climate, and also scarily reminds me of the sci-fi horror film, 'The Purge', where for 12 hours in one day of the year, ALL crimes become legal. Changing social norms to ones where humans would whole-heartedly appreciate and protect the planet wouldn't just occur overnight, it would take serious time, effort and powerful people to get the ball rolling.

How do we drive the economy away from fossil fuels?

In Schwägerl's new book (2014) he creates an interesting fictional future scenario. Imagine that China, one of the world's leading economies, becomes home to an extremely influential green movement which forces global governments to act. These fictional protests from China influence an American band to write a viral song called 'Kill the Future', which causes 'panarchists' to remove items from people's shopping trolleys and replace them on the shelves (encouraging less consumption). Supposedly, from a series of events stemming from this initial green movement, the billions of pounds in subsidies in fossil fuels would be diverted to renewable energies and technologies. The change that needs to take place in reality is convincing the global population that we can change our behaviour and actions, and this can change the world for the better (Graham-Leigh 2015).

Getting out of "Holocene thinking"...

In the interview, Schwägerl (2015) argues we should embrace the Anthropocene, and stop seeing the environment as a separate entity from humans. He claims we currently take the environment for granted, using it as a dumping ground for our waste, and a source to exploit for materials and food amongst other things. In his book, Schwägerl (2014) adopts the term 'invironment' as opposed to 'environment' in the Anthropocene as a way to show our inherent connection with nature and the environment. I'm not sure if it'll catch on as a term in reality, but it's a nice way to highlight that in the Anthropocene we should see the 'outside world' of nature as an inseparable connection to humanity.

The human race boasts incredible knowledge, scientists, artists, leaders, and cultural influences. With the state of our current technology and understanding of the planet, why shouldn't it be plausible for humans to overcome short-term planning mindsets and economic mismanagement (Graham-Leigh 2015)? One day in the future, will we be able to see in the rocks, archaeological artefacts, and palaeoclimatic proxies, that humans turned the Anthropocene from a story of exploitation and environmental damage, to one of cooperation, innovation, and humility? I guess only time will tell...

* The book by Schwägerl (2014), 'The Anthropocene: The Human Era and How It Shapes Our Planet', does not have an online copy at the moment, but from reading snippets from the hardback version I can tell you it is well worth a read, with a foreword by Paul Crutzen himself! You can read the first few pages online here if you're interested.

Water in a Warming World

During my evening procrastination (it was productive, I swear...) I came across a visually arresting website, marketed as the first Anthropocene educational web portal, developed in 2012 by a series of research programmes and organisations. I'll try to post about different parts of the website in the following weeks, as a break/reward (for you and me!) between some of the more lengthy philosophical posts! For now, if you can spare a mere 4 minutes from your Tuesday night, this short fascinating video from their site on water in the Anthropocene is well worth a watch:

I know I've been a bit critical in regards to the Anthropocene over the last month or so, but this does highlight the impacts humanity has had on a planetary scale on the global water cycle. The video claims we've built 48,000 large dams, drained 50% of global wetlands, use an area the size of Africa for our livestock, and altered integral parts of Earth's water cycle. Anthropogenic climate change is causing wet regions around the world to get wetter, and dry regions to become drier (Niang et al 2014). There is no doubt that humanity's actions on Earth have already changed the way we see and use water on our planet. Big challenges face the human race in the near-future: can we innovate our way out of water shortages? Will we be able to prevent "water wars"? Fundamentally, will we be able to adapt to the world and future we have unintentionally, yet forcefully fabricated?

If the topic of water in a warming world gets you fired up, I'm also the lucky owner of a second blog, looking at how water is impacted in East Africa due to climate change. If you fancy a read, you can visit it here! 

It was as if the Holocene never existed...

Cast your minds back to one of my first ever posts (here's the link if you can't), where I summarised the main proposals for the onset of the Anthropocene - unsurprisingly, one of the hottest debates in the discourse to date. Today I'll be focusing on one key idea: what if the Anthropocene and the Holocene are coeval? In other words, what if the Holocene was replaced entirely by the Anthropocene?

Smith and Zeder (2013) are the main proponents of this argument, though Certini and Scalenghe (2015) have recently moved away from their proposal of an onset with 'Anthropogenic soils' in 2,000 BP (Certini and Scalenghe 2011), and instead towards one which agrees with Smith and Zeder (2013), arguing that the onset of the Holocene should instead be renamed and reconfigured to become the Anthropocene. Certini and Scalenghe (2015) do, however, still believe that anthropogenic soils (e.g. those affected by repetitive ploughing, application of fertilisers, contamination, enrichment etc) could provide an additional auxiliary stratotype to the 5 existing stratotypes recognised for the Pleistocene-Holocene boundary (Walker et al 2009). The basis of the arguments for regarding the Holocene and Anthropocene as coeval are as follows:

• Origins of agriculture approximately coincide with the onset of the Holocene (11,700 years BP) (Balter 2013; Certini and Scalenghe 2015). 
• Niche Construction Theory (NCT) - the wide-spread domestication of plants and animals during the early Holocene allowed human societies to significantly modify ecosystems (Smith and Zeder 2013). This is different from other species as humans pass these behaviours on throughout generations through social learning (Smith and Zeder 2013).
• No new golden spike (GSSP) would be necessary as we could continue to use the Holocene's existing spike in the NGRIP Ice Core (Certini and Scalenghe 2015).
• Might be more useful to merge the Anthropocene with the Holocene, as there is abundant evidence of human societies developing tools (domesticates) to be used in the subsequent 10,000 years to reshape ecosystems, as opposed to 'limiting it to the last two centuries on the basis of extant geological standards' (Smith and Zeder 2013).
• The coeval proposal provides a solution to the challenge of satisfying formal geological standards needed to establish the Anthropocene as a new epoch (Smith and Zeder 2013).
• The transitions between previous geologic time intervals (e.g. P-T extinction event, lasted 61±48 thousand years (Burgess et al 2014)) makes the 12,000 years between the onset of the Anthropocene and Holocene seem a 'ridiculous range of time', thus it is better to see them as one combined epoch (Certini and Scalenghe 2015).

Well, one might argue, why bother changing the name of the epoch we are in from the 'Holocene' to the 'Anthropocene'? Smith and Zeder (2013) propose that the ICS may consider using 'Holocene' in scientific contexts, and the 'Anthropocene' in media and popular discourse. Essentially this would mean keeping the Anthropocene as an informal term for the time we live in, continuing its use to encourage action and focus attention on human impact on the planet. Certini and Scalenghe (2015) also argue the term 'Anthropocene' is more 'durable' than the Holocene. "Durability?" you ask? Let me explain what they mean. Their argument is that a new glacial inception (ice age) would end the Holocene (as the basis of the Holocene is that it is an interglacial and marks the end of the last ice age), but that the same ice age would not stop human impact on Earth (as the basis of the Anthropocene is the focus of humanity's effects on the planet, and not it being an interglacial) (Certini and Scalenghe 2015). I'm not entirely convinced by this argument or the example of an ice age; a new ice age will only occur once atmospheric CO2 levels are low enough (~280ppmv) and albedo high enough to allow ice growth and expansion (see an earlier post of mine). Surely allowing this to occur would signify the end of human alteration of Earth Systems through fossil fuel combustion, deforestation etc? UNLESS humanity makes a deliberate attempt to modify Earth Systems in a way which permits a glacial inception (something I personally can't see happening any time soon...).

Should the focus of the last 11,700 years, and (hopefully) many millennia to follow be entirely on humans? Are we bold enough to conclude that this epoch in Earth History will always be characterised by human impact on Earth Systems, even far into the distant future? Not everyone agrees with the idea that the Anthropocene and Holocene should be coeval. Clive Hamilton (2014) heavily criticises Smith and Zeder's (2013) approach of focusing on ecosystems and the biosphere, as opposed to the Earth in totality in a guest blogpost on the Anthropocene Review Blog. Hamilton (2014) is openly frustrated by Smith and Zeder's paper, as according to him, they have entirely misunderstood the concept of the Anthropocene. He argues the Anthropocene must focus on when humans first started altering the Earth as a whole, and not just ecosystems. To summarise his post, he basically tells ecologists to "butt out" (his words, not mine!) in trying to redefine the Anthropocene. Ouch. 

My thoughts on the matter

I can empathise with wanting to make the Anthropocene and Holocene coeval purely for the simplicity and ease it would have over debating new onsets which must obey strict geologic standards. However, the reasoning behind this combination of epochs should not be for ease or simplicity, it should be because the evidence is overwhelming, which in this instance, I think it is not. There are many other proposals for the onset of the Anthropocene which have far more convincing and stand-out examples of humans altering Earth Systems, such as the Trinity atomic detonation, producing global radioactive fallout as well as representing a momentous change in humanity's ability to both create and destroy at the same time with a new nuclear age (Zalasiewicz et al 2015). Furthermore, is there any point in changing the Geologic Time Scale if we are just to continue using the Anthropocene informally and the Holocene formally? The only difference is that we would be discussing the same length of geologic time, and not using the Anthropocene for interpreting the last few centuries (or decades, depending on your view).

Also, with reference to NCT (Smith and Zeder 2013), should the example of humans first altering ecosystems with plant and animal domestication not be something more paramount? For example, the Haber-Bosch process of the early 20th century provides a much more significant instance of humans artificially producing nitrogen, completely modifying the nitrogen cycle even now in our present day. Or, the instance of when human creation and use of chlorofluorocarbons (CFCs) led to a large hole developing in the ozone-layer above Antarctica? There are many other, perhaps more convincing examples of humanity altering ecosystems as well as the Earth System as a whole, and not just the terrestrial biosphere. I do, however, agree with Certini and Scalenghe (2015) that ending the Holocene and starting the Anthropocene after a mere ~12,000 years seems like too short an amount of time to end an epoch and begin another. Although, this is not to say that the best way over that hurdle is to merge two epochs with separate identities and characteristics into one with confusing formal and informal terminology. I'm still of the opinion that if the Anthropocene is to become formally defined, it should not simply replace the Holocene epoch.

Pause for thought

Source: Chris Madden

This is a satiric yet thought-provoking cartoon comparing the Anthropocene to the demise of the dinosaurs from Chris Madden's collection. Will a layer of anthropogenic waste show up in the rock record when we look back in hindsight millions of years into the future? More importantly, will the event that creates this layer mark the end of the human race?

Nature: the undisputed champion of the (changing) world?

"Nature is gone.* It was gone before you were born, before your parents were born, before the pilgrims arrived, before the pyramids were built. You are living on a used planet. If this bothers you, get over it. We now live in the Anthropocene—a geological epoch in which Earth’s atmosphere, lithosphere and biosphere are shaped primarily by human forces. Yes, nature is still around—back-seat driving, annoying us with natural disasters from time to time, and everywhere present in the background—but definitely in no position to take the wheel."

The above quote (emphasis added), written by Ellis (2009) in a controversial article, claims nature has become a "back-seat driver" in the vehicle driving the Earth, and who is at the wheel? Humanity. The entire argument for the Anthropocene as a formally ratified geologic unit is that human activity dominates the global environment (Finney 2014). Visconti (2014) argues this suggests geological processes will not be relevant into the future. Here, there is a fundamental weakness which must be addressed in the concept of the Anthropocene: natural events in the Earth system have the power to obliterate any traces of a 'human-influenced environment' (Visconti 2014). If you asked Ellis, I'm sure he would agree that humans have taken control of the planet, and that nature has become akin to some sort of 'background noise'. If you ask me, I'm not sure that this is true. 

A fundamental question which needs addressing by the AWG before ratification is whether geological processes can still overwhelm human activity (Finney 2014). Sure, human impacts are globally widespread and in many cases, seriously detrimental to our planet's natural systems. BUT, as we know, geological time is discussed in units of millions, hundreds of millions and billions of years...are the signatures of humanity at shallow depths in Earth's crust even relevant on this time scale (Finney 2014)? As Finney (2014), Visconti (2014) and Moore (2013) argue, how long will it take before the "defining features" of humanity on Earth would be wiped away, as if a smear on a windscreen, by catastrophic natural phenomena? For example, another huge asteroid impact, gigantic tsunami, or supervolcanic eruption (e.g. Yellowstone) would surely overwrite any present/near-future stratigraphic record of human activity on the planet (Finney 2014; Visconti 2014). As noted by Visconti (2014), even if human actions result in a catastrophe e.g. the Sichuan earthquake (read here for how it could've been caused by dams), the signals in rock remain characterised by the natural event. 

Personally, I think Nature will always have the
upper hand in the long-run. (Source)

Even if today we believe that humans can and already are rivalling the great forces of Mother Nature (Steffen et al 2007), can we honestly argue that nature has become inferior to the powers of the human race? I do agree that the period of time we are in at the moment (be that the Holocene or Anthropocene) is approaching terra incognita and that we are pushing planetary boundaries to unknown levels. Therefore, I do not disagree that humans are having great and potentially long-lasting impacts on the planet (e.g. see here for how we may have postponed an imminent ice age!), but I cannot agree with Ellis (2009) that nature has become a 'back-seat annoyance'. 

From an elemental viewpoint, we are like ants crawling around a big lump of rock, moving at incomprehensible speeds around space, 100% dependent on nature. No matter how much we put humanity on a pedestal, we cannot control the trajectories of asteroids, the behaviour of the Sun, or the natural long-term cycles that Earth has undergone in its 4.5 billion year lifetime. We are completely at the mercy of nature. To say that nature does not have the wheel of the vehicle driving the planet is based on completely false assumptions (Visconti 2014). Additionally, we mustn't see nature as a rival or opposite force. We should try to work alongside it, together, and embrace that we have become powerful as a species, but that nature could change that in a blink of an eye. We can only hope that nature is benevolent to us, despite our damaging and careless alteration of Earth's natural systems in recent geologic time. 

So, to respond to the initial quote by Ellis (2009), I fundamentally disagree. In fact, we humans are the passengers in this vehicle, we are the back-seat drivers and occasional annoyances, and nature is at the wheel, as it always has been. Humans are just along for the ride. Once we have left this planet behind (be it through extinction or emigrating to Mars), our Earth will continue to live on until its natural end.

* It isn't the purpose of this blog to go into the arguments of whether humans and nature are separate entities, or one combined force, or whether nature is indeed natural, or if everything is unnatural, and what is natural...that would be a whole other blog entirely! If you are interested in these debates, drop me a comment, and I'll pass on some good literature on the topic.

Human or Earth history?

When you think of the Anthropocene, what comes to mind? Do you envisage fossil fuel power stations, industrialisation, exponentially growing human populations, atomic bombs, globalisation and economic expansion? Or, do you picture the human-induced changes to Earth's atmosphere, sedimentary layers, and stratigraphic composition?

If you thought more along the lines of the first description, it may be that you (probably unintentionally) perceive the Anthropocene more as a unit of human history than Earth history. We humans have historically divided blocks of time into different named periods, making communication and analysis easier (Edwards 2015). Take for example the Victorian era, precisely defined by the reign of England's Queen Victoria (1837-1901) (Edwards 2015). Human divided time periods can also be based on stages of cultural development, such as the Bronze Age, which does not have a specific start and end date as it depends on the place and specific civilisation's development (Edwards 2015). Contrastingly, the Geologic Time Scale relates to stratigraphic rock records, correlating to chronostratigraphic units of time. Does this informality make the Victorian era or Bronze Age any less important in human development? No. But it does make them units of human history, and not Earth history.

The Anthropocene: a unit of human history, or Earth history? (Source)

Crucially, we must also decide if the Anthropocene is a recently historic unit of time, or if it is instead an idea for a future unit of time (Finney 2014). The ICS, who create and decide on units for the International Chronostratigraphic Chart (ICC), do not postulate for the future, they assess the stratigraphic record which exists today. Some arguments within the Anthropocene discourse often follow a line of "Oh, but future geologists will look back in millions of years and see chemicals, plastics and atomic fallout in the strata"...have we forgotten that the ICS does NOT consider what might make future Earth History? That is not the way it works. There is no predefined geologic record for the future. If the Anthropocene will be more significant in the future, then that is when it should be classified and formally ratified. Having said that, is the Anthropocene such a profound concept that the unit of time should no longer conform to traditional, predefined time spans and standards as set out in the ICS Stratigraphic Guide?

As Finney (2014) has argued, human-induced impacts on Earth Systems are just starting to be recorded in sediments, but we cannot be sure that a significant and unique sedimentary signal will assemble. Can we really justify a profound change in the ICC and GTS, one which could end our current Holocene interglacial epoch, based upon potential projections and hypothesising of what the future might show us, considering there currently seems to be a lack of consensus based on the past? Finney (2014) also raises an interesting point (once which I had not considered until now), that our precise human observations and measurements are those that would be used for studying human-induced impacts, as opposed to looking in stratigraphic records for information. The stratigraphy for the Anthropocene looks pretty bare in comparison to the multitude of events which humans have observed and recorded over recent history (Finney 2014). 

Finally, I must address the elephant in the room when it comes to the whole concept of the Anthropocene. Are we being a little anthropocentric, assigning an interval of Earth History to our human existence on the planet? Why must we hastily define the Anthropocene as a formal unit of geological history, when its use may be just as powerful to the global population as an informal term? I believe that recognising that we are in the "Anthropocene" (whatever that may mean to you) could go one of two ways. It will either be a huge wake up call, alerting politicians and the general public to our detrimental effects on the planet, OR, it will be an anthropocentric comfort, a pat on the back, knowing that humanity is just that powerful and a dominant God-like species. The AWG must address whether the Anthropocene concept has stemmed from an anthropocentric perspective, rather than purely a geologic and scientific one, and if it belongs as a truly significant era of human history as opposed to one of Earth history. 

A human concept, lost in stratigraphy?

"As stratigraphers, we require criteria to map the Anthropocene with relevant and consistent meaning. Presently, we are left to map a unit conceptually rather than conceptualizing a mappable stratigraphic unit."

The above quote (emphasis added), written by Autin and Holbrook (2012) in an article in GSA Today, forced me to question some fundamental arguments in this debate. Is the Anthropocene a term rooted in pop culture, based more on conceptual meaning in search of a stratigraphic signal, as opposed to starting with a distinct stratigraphic record? Finney (2014) asked the very same question, and I find his opinion akin to mine. The more I become involved with the Anthropocene debate in this blogging journey, the more I am questioning everything I once believed at face-value without a second thought. The idea behind this post is rather like the famous question of what came first, the chicken or the egg? In this instance, should concept come before stratigraphic evidence?

A defining feature of the Anthropocene, distinct from other units of geologic time, is that the proposed epoch is in the present and continually evolving. Therefore, instead of looking back in retrospect at fossils and stratigraphic evidence, the conceptualising step must come first, with stratigraphic evidence following later. Whether this is the 'correct' way to classify a new unit of geologic time is dubious. Historically, changes in stratigraphy have been identified, and then conceptual units of time have been assigned to these clear shifts and events in the strata. In our present day, the world has identified a new concept, one which views humanity as a centrally dominant geologic force, and now we're searching for a stratigraphic signal to fit that concept. Perhaps this signifies a time for change in how the Geologic Time Scale (GTS) should be constructed in a present-day mindset, recognising that fossils and stratigraphic evidence can become secondary to conceptual assignments. 

Finney (2014) continues this philosophical debate by questioning the conceptual basis of the GTS, asking whether it is suitable to be applied to 'chronometers of recorded and future human history'. As so much of what constitutes the Anthropocene is in the present and near-future, should it formally become part of the GTS, considering that all units currently recognised are events which occurred deep in the past (Finney 2014)? I agree with Finney that this is a very important question that needs addressing by the AWG, but I do not agree that the Anthropocene (or any other future time intervals) should be written off from formalisation just because it has not occurred in the deep past. In my eyes, the GTS should modernise to accommodate for new periods of time which will likely come to fruition during humanity's existence on the planet. This may be as simple as providing alternative time resolution intervals which acknowledge shorter events and ages (e.g. centuries to millennia) within larger chronostratigraphic units (e.g. epochs and periods). Clearly the time resolution currently used on the GTS (millions to billions of years) would scarcely recognise the Anthropocene, a blip of time in Earth's 4.5 billion year history. So, should the GTS downscale to additionally accommodate smaller, yet important, intervals of time, extending the use of GSSAs? Or, should the GTS refuse to formalise these smaller events and continue formalising only those longer time intervals with robust GSSPs and a clear stratigraphic record?

Crucially, the Anthropocene is the first proposed geologic interval whereby the focus itself (humanity) is able to influence and change the very nature of the time wished to classify. This brings me onto my next big question to address: is the Anthropocene a unit of human history rather than Earth history?

Age over Point?

Geologists are set on finding a golden spike (GSSP) to mark the onset of the Anthropocene Epoch, as has been necessary for (almost) every other geological time unit in history. But it seems this marker needn't be golden, nor a spike; recently there have been arguments that the Anthropocene could instead be defined by a numerical age boundary (GSSA). A GSSA is essentially a point of time in the human calendar, a chronological reference point if you wish, assigned as a starting date for a unit of geological time. At present, the ICS have only defined periods of time older than ~500 million years ago (Ma) using GSSAs and chronometric dating (aka most of the Precambrian). This is because there is an insufficient fossil record/preservation level to identify key events needed for a GSSP this far back in history (Lewis and Maslin 2015).

Does a GSSP offer a practical advantage over a GSSA? Currently, all units within the Phanerozoic Eon are defined (or planned to be) by golden spikes (Zalasiewicz et al 2015). This wasn't always the case, though. The inception of the Holocene used to be 10,000 radiocarbon years BP (before present). This officially changed 6 years ago to 11,700 years b2k (before 2000), marked by a GSSP in a Greenland ice core (see here; Walker et al 2009). Prior to the switch from GSSA to GSSP, scientists were studying an enormous range of aspects within the Holocene without major issues in its age-based boundary. Does this show that age-based or stratotype-and-point-based boundaries are irrelevant to the deeper context and events within that time period?

The Trinity atomic bomb, pictured 16 milliseconds after
detonation, could be the defining marker for the Anthropocene.
(Source)

Zalasiewicz et al (2015) (note, the majority of the AWG...) recently proposed the Anthropocene should start when the Trinity atomic bomb was detonated in Alamogordo, New Mexico, at 05:29:21 Mountain War Time (+-2s), July 16, 1945. The authors liken this assignment of the age-based boundary to that of the Cretaceous-Palaeogene boundary: marked by the moment a meteorite struck the planet, leading to the demise of the non-avian dinosaurs. Though radiogenic fallout became more prominent on a global scale in the years to succeed, this GSSA is based on the first ever nuclear test, representing a clear historical turning point (Zalasiewicz et al 2015). Finney (2014) also recently considered the use of a GSSA for the Anthropocene, arguing that a GSSA would be more accurate than a calibrated onset formulated from a GSSP, with a date in millisecond precision. 

As it stands, some people disagree that any time period should be defined geologically by a numerical age. Bleeker (2004) argues that the Precambrian needs redefining from the present chronometric divisions to a more 'natural' timescale. By this, Bleeker means the use of GSSPs in the rock record to split the Precambrian into eons accurately reflecting stages of planetary evolution. If you're a bit of a geology/Earth history nerd like me (*waves*), I highly recommend giving Bleeker's paper a read...

...I digress. By raising this point, I'm asking you: if we are still contesting the use of GSSAs for periods of time where fossils do not exist (and thus necessitate an alternative boundary method), then how likely is the use of a GSSA where fossils do and will soon exist? Lewis and Maslin (2015) argue that because candidate GSSP markers exist, there is no need for a GSSA. But are those candidate GSSPs the best suited for this epoch? If the answer is no, then a GSSA could be more beneficial. It would also allow the fossil record to develop more fully, better representing the epoch of time than if we rush into using some proposed GSSPs, which, in hindsight might not depict the Anthropocene accurately (see this post for more!). The age of the Anthropocene is still very much in its development phase, and thus selecting a numerical age for its onset may prove a solution for defining the time whilst fossils and potential GSSPs continue to develop. 

Key take-home questions

We know that anthropogenic effects on Earth systems are now being recorded in sediment and rock, but will a significant enough stratigraphic record be produced for the future? Do we know for certain what changes humanity will bring to the planet? Would the main proposed GSSA (Zalasiewicz et al 2015) be superseded by future signals (e.g. a mass extinction event or meteorite)? Is the use of a GSSA practical and able to be used effectively by scientists? Additionally, would the use of a GSSA help engage other academic circles (besides geology) into the emerging Anthropocene literature?

My thoughts on the matter

For this recent chapter in human and Earth history, I believe there are many changes to be made to the way we visualise geologic time units. The Anthropocene is unique in that much of its content is in the present and near-future, and only the relatively recent past. In a time where everything is changing at rapid pace, the ICS need to adopt new ways to represent different ages within the Holocene (or Anthropocene, depending on your view) with techniques best suited to each time period, be that a GSSA or GSSP. I agree with Zalasiewicz et al (2015) that a GSSA may be a simpler way of defining the Anthropocene in the present day, as within the many proposed onsets, few have a definite and suitable GSSP (see a previous post of mine for GSSPs). As long as the GSSA chosen represents the moment we wish to characterise the nature of this epoch, and that there are various global stratigraphic signals relating to and following that moment, I see no issue in choosing an age over point. 

Do you have an opinion on this debate? Don't hesitate to voice it in the comments below!

Generation Anthropocene: Are we doomed?

I found this really interesting video on YouTube earlier, and wanted to share it with you all. If you're not already familiar with TED talks, I suggest you watch a few! They're very concise, intellectual, yet accessible talks on a whole spectrum of important topics.

As Mike Osborne and Miles Traer say, lets put on our "Anthropocene goggles" and begin to appreciate that the more we study the world, the more we realise humanity is an integral part of it. According to these two fairly optimistic scientists, the Anthropocene doesn't mean the end of anything, but it does mean that everything will change. Can humanity, the cause and defining feature of the Anthropocene, adapt to these changes?

What are your opinions on the matter? Don't hesitate to comment below!

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.