Are we living in the Anthropocene? - Part 2

Google the Anthropocene and you will be overwhelmed by news articles and research into this newly proposed geological time – my latest blog post being somewhere down the list. I wanted to explore both sides of the argument that we are living in a human-influenced geological time, but there was just too much to squeeze into one post. I have already highlighted arguments in support of the Anthropocene but now let’s take a look at why we might all be jumping on the Anthropocene band wagon a little too quickly…

Harmful human impacts on Earth paint such a negative picture it’s hard not to hand yourself straight over to the Anthropocene. We have become far too accustomed to hopelessly accepting there is nowhere natural left on Earth.  However, we could be overestimating the extent of human influence at a local scale. In Conservation Biology, 2001, Caro et al. suggest there are still ecosystems that we have affected a lot less than we fear, called intact ecosystems. 

An ecosystem is described as intact if the majority of native species are still present and play the same functional roles as they did before extensive human settlement. These include areas of low human density - like equatorial, subtropical and arctic latitudes - and high biodiversity, which do still exist. The Amazon Rainforest, Canadian Boreal Forests, the Rocky Mountains and lake regions under Antarctic Ice sheets are all examples of regions with intact ecosystems.

Canadian Boreal Forest

I'm not suggesting that the presence of such ecosystems allows us to ignore the rest of the changes humans have caused around the globe, but it is valuable to remember there are still natural places left on Earth, and to decide how these need to be protected. 

As Chris D. Thomas reminds us in Nature, change isn't always a bad thing. Even if we are living in the Anthropocene, not all human activity has been detrimental to biodiversity. Humans are often responsible for introducing invasive species to ecosystems, which is commonly believed to be harmful to biodiversity. Stuart L. Pimm in The Future of Biodiversity, 1995, suggests that invasive species are a factor at the centre of most extinction mechanisms. However, according to Thomas, invasive species can actually increase diversity because less than one species dies out on average when a new species is introduced. 

It may be concerning that human activity such as development and land use change can displace multiple species from the original habitat, in turn supporting a smaller range of species and losing diversity. However, these man made areas create new habitats which promote speciation. A greater diversity of habitat type correlates to a greater biodiversity. Although you might think it is more important to conserve existing species, it is also important to consider future species and hybrids evolving during our time - or should I say the Anthropocene?

Whether human impacts to the Earth have been positive or negative, the spread of anthropogenic influence has only left few natural areas, so the great deal of support out there for the Anthropocene is understandable. If we really are in this new geological epoch, the question to ask next is when did it begin..?

The Earth in human hands 

Are we living in the Anthropocene? - Part 1

As an Earth Science student I have spent countless hours during lectures and out in the field trying to decipher what a certain rock sample or outcrop can tell us about the climate, atmosphere and environment at the time of deposition. So what happens during the next 100 million years when the rocks of our time become upthrust, eroded and exposed to the Earth’s surface? What will they say about our time on planet Earth? One thing is for sure; we have made a huge impact to the conditions on our planet, and these impacts are likely to be reflected in the future landscape of Earth. Whether these impacts will be great enough to distinguish rocks created before the evolution of humans to those being created today sparks debate over the Anthropocene.

Looking at a current geological timeline the Holocene is the present epoch which stretches back 10,000 years, but there is a growing scientific movement proposing we have entered the Anthropocene – a time characterised by human impacts to the Earth. This suggestion was first put forward in 2002 by Paul Crutzen, a Nobel Prize-winning atmospheric chemist. The term has since taken off, receiving support from The Geological Society of London Stratigraphy Commission and Jan Zalasiewicz. The Anthropocene could soon be made a formal unit of geological time, and be the first to be done so live.

Geological times are recognised by specific rock sequences, characteristic of Earth’s atmosphere, biodiversity and ocean acidity. Anthropological impacts will therefore be recorded in the rock record if humans have an influence on these factors. Arguably, human activity has already impacted every corner of the globe, from deep ocean environments to atmospheric composition.

Even at first glance, numerous examples of human impacts on biodiversity spring to mind. The expansion of the human race demands widespread agriculture which reduces numbers of native plants in preference to large expanses of single crops. The removal of forest for this purpose has knock-on effects of increased erosion. Fertilisers used for food production rinse into rivers, lakes and the ocean where they promote algal plumes. Human activity introduces invasive species which can eradicate native species. Ocean acidification is causing loss of coral species which will change the future of ocean rocks.

We are even more familiar with climate change. We constantly hear about carbon emissions in the media, and atmospheric carbon is now a third higher than in pre-industrial times, which links to global rises in temperature, in turn causing glacial retreat and further losses in biodiversity. Other processes of urbanisation such as construction and the damming of rivers, coupled with deforestation, as mentioned, are eroding excessive amounts of sediment to add to stratigraphy. Not to forget the legacy of plastic waste we are leaving behind us.

By briefly touching on the variety of human interactions with natural cycles you can see why the idea of the Anthropocene is becoming more widely supported. As each one of these changes is recorded by Earth they will create unique rock sequences that will, if we truly are in the Anthropocene, point towards a definitive changing point in Earth stratigraphy.

-Video source

Are humans the greatest geological force on Earth?

In a recent late night rant my flat mates were discussing how great and successful humans are, their view being that no other species can compare to our knowledge and power so we dominate planet Earth. They seemed to think this was brilliant for us. But I don’t think humans have only made positive changes to our world, surely continuing to exploit Earth for our own technological advancements isn’t necessarily something to be celebrated? So as useless as it was at 2am for me to challenge their opinions, I did try, and it got me thinking. The big questions in my mind are how large is the footprint left by the human race going to be? Are humans overtaking other natural processes to becoming the driving force of change on our planet? Would this make us the greatest geological force on Earth? Whilst three students sat in their kitchen late at night bragging about mankind may not put forward the most enlightened argument, they could be more right than they first thought about humans controlling the planet.

The idea that humans are ‘taking over the world’ by making so many global changes introduces us to the theory that we have pushed ourselves into a whole new geological age, the Anthropocene, as discussed in the New Scientist Environment blog. This hugely supports the idea that humans are changing the face of geology. Through this blog I will be exploring the evidence for the Anthropocene alongside the causes of many of the greatest global changes throughout human evolution. The areas I’m interested in include the loss of megafauna, global climate change and how the loss of modern biodiversity corresponds to previous mass extinction events – all with the aim of identifying who or what is dominating our current global environment.