Anthropogenic Transformation of the Terrestrial Biosphere: A Novel Force?

Welcome back!

As promised, in today’s post I will be reviewing the idea that human systems represent a novel force of biospheric change, in other words one that is not duplicated in nature and one that is entirely unique.

In the Ellis paper, human development is organised into three major stages. I introduced these briefly in the last post but to refresh your memory here’s a quick run-through of what we’ve been getting up to over the past 2.5 million years…

Way, way back (around 2.5 million years ago in fact) we were organised into tribes. Stone tools were up-and-coming and fire was all range. We used these new gadgets to improve our hunting and gathering livelihoods. Our population stood at about several million and by 0.1 to 0.15 million years ago we had spread across most of the terrestrial biosphere.

Our palaeolithic ancestors began to use tools in hunting. Source: BBC

This all sounds harmless enough to me, however Koch & Barnosky (2006) suggest that the use of tools and fire to clear vegetation may be responsible (or at least in part responsible) for megafauna decline. Already we’re getting quite serious, and there’s not a fossil fuel in sight!

What we are really interested here is whether or not Palaeolithic human systems transformed ecosystems in ways that were entirely novel. Yes we used fire and yes there were megafaunal extinctions, however, Bowman (2009) says that these are both common effects of climate variation and so these processes were not unprecedented at the time. No evidence of novel transformation in the Palaeolithic era, but let’s move on to something more sophisticated!

Around 0.01Ma, we (Neolithic humans) learned to domesticate plants and animals for food. We were getting really handy with evermore powerful tools (in fact I believe the first B&Q was opened around 0.02Ma) and our ability to engineer the ecosystems was on the increase! Scientists believe that at this point our populations covered the vast majority of the terrestrial biosphere and by 1800 numbers had reached 900 million! (Ellis, 2011).

New research has found that Neolithic farmers used manure as a fertiliser on crops. Source: BBC

Any signs of any novel transformations by the Neolithic human system? Well, in contrast to what Koch & Barnosky(2006) said, Smith (2007) argues that the clearing of native vegetation and herbivores and their replacement by engineered ecosystems populated with domesticated plants and animals, does in fact represent an entirely novel biological process. I suppose when you think about it the evolution of many agricultural species is no longer a natural process, it is something that has come to be entirely controlled by humans.

And finally we progress to the industrial human system where we begin to burn fossil fuels for energy,  and we develop technologies for enhancing human survival rates, such as antibiotics and synthetic nitrogen fertilisers. Ellis(2011) identifies three novel biospheric processes that were introduced by the industrial human system:

1. The use of fossil fuel energy to replace biomass fuel and human and animal labour
2. The industrial synthesis of nitrogen fertilisers to increase productivity
3. The genetic engineering of species to increase productivity and yields

Genetically modified crops account for almost a quarter of all crops grown in the USA. Source: UNEP/GRID-Arendal

All of these novel processes serve to revolutionise our capacity to engineer the ecosystem and transform it.

From this three-stage model, it seems that human transformation of the terrestrial biosphere is consistent with the development of agriculture, which we first see during Neolithic times. Various technological advancements of the industrial era, for example the development of nitrogen fertilisers, certainly act to drive and intensify land-use changes.

However, it would be wrong of me to offer you this model without giving some kind of critique. Of course, anything that tries to explain such a complex process of events over a concise number of stages always runs the risk of oversimplification and I think that this may be the case here. However what it does do is it enables us to make a rough assessment of human systems as a force for transforming the terrestrial biosphere, and this is what I hope I’ve done here!

I think one further post is needed to neatly wrap up this topic so stay posted for my summary of anthropogenic transformation of the terrestrial biosphere.

P.s. I really recommend the Smith paper I mentioned above. It gives a really interesting insight into how early humans first gained the ability to transform the ecosystems and it talks in greater deal about processes of ecosystem engineering.