The short communication by Barnosky & Hadly examines the current fundamental environmental ‘problem’ for human populations through the lens of the “Anthropocene” concept, i.e. will some human populations:
continue to develop using a “business as usual” model that has been shown to elevate environmental risk to all human populations, or
alter societal practice in an attempt to reduce the environmental risks now and for future generations.
Barnosky & Hadly straightforwardly and succinctly present the case that, based on the weight of evidence from the collective scientific endeavour of the global community, humans are now fundamental altering the functioning of planet Earth; a view further supported by the recently published Intergovernmental Panel on Climate Change report (IPCC, 2014).Throughout the period of anatomically modern human existence (Homo sapiens sapiens, the last c. 200,000 years) populations have experienced a variety of environmental changes. Exposure to environmental change has had both positive and negative impacts on societal development (e.g. Gosling & Williams, 2013; Hodell et al., 1995).
This paper is a very interesting read for anyone working in the field of palaeoecology. It briefly discusses some of the key criticism of earth systems science research and demonstrates how a good understanding of our past is critical to our future projections.
“Nature of the Science”
Often Earth System Science is described as being “fuzzy”. It doesn’t always fit the model Popperian approach to science whereby refutable hypothesis are defined and tested. The authors point out however that this is somewhat an unfair criticism. The Earth system is complex, non-linear and often there are no cause-consequence relationships. The scientific method involved is much more complex and often we are trying to understand phenomena that occur over immense timescales. To demonstrate this a little further the authors use the example of freshwater acidification.
“By choosing a variety of field-based case studies with or without key characteristics, each of which was a putative cause of acidification, it proved possible to isolate past variables such as land-use change or catchment afforestation and thereby home in on the only remaining hypothesis not rejected by the evidence, namely the dissemination of industrially generated SO2.”
Rather than testing and refuting or accepting whether industrial generated S02 was causing acidification, cumulative research showed it to be the universal variable across multiple examples. Often when we make inferences about environmental change we have multiple working hypotheses which stand until more and more evidence arises to support one over the others.
“Toward Projective science”
Projecting the future consequences of climate change is of vital importance for society and critical to policy and mitigation strategies. Climate models are really the only tools at our disposal in trying to understand future scenarios. However models alone cannot provide us with all the answers, the paper demonstrates that the only evidence we ever have is from the past.
“All the evidence we have regarding environmental change comes from the past, whether of the previous few seconds as changes are logged continuously, or of the more remote past revealed through the study of environmental archives.”
If we want to refine our models and have better projections in the future then these tools must have the ability to capture the empirical evidence we have from the past. Future projections are based on data-model comparisons; this is an interactive relationship that is ever refined as each side gains in knowledge and skills.
Last week we changed our regular lab meeting, when we all normally discuss a particular paper, to each presenting a general view on the articles published in the first issue of the new journal The Anthopocene Review (SAGE publication). In this lab meeting each member presented and lead discussion of issues within a different paper.
In my case, I had a very interesting paper by Anthony J McMichael about changes in life expectancy (Human population health) related to the human impact caused at global scale during the Anthropocene (defined in the paper as the last 200 yr). Here is a brief summary of the main topics discussed in the paper:
The paper deals with life expectancy trends during the human history on Earth, understood not as the individual health care but as a population or community collective (the “herd” effect), being this two independent topics.
The first section is a nice trip for human evolution and its relationship with the environment, distinguishing three different phases of environment-climate-human relationship:
The Pleistocene (c. 2.6 million – 11,000 years ago): characterised by environment-driven changes;
The Holocene (c. 11,000 – 200 years ago): with cultural-driven changes promoted by the potential of farming. Survival, although relying in culture changes, was still dependent on climatic stability (survival changes caused or amplified by adverse conditions); and
The Anthropocene (last 200 year, as defined in this paper): when humans have become a dominant force on the world stage, being nowadays the major contributor to climatic change.
Finally, the author shows several direct and indirect pathways by which changes in climatic conditions will affect the human health, encouraging the urgent need of an environmentally sustainable way of living.
If you are interested to find out what your ecological footprint might be try these online tests:
This comment piece looks at the Anthropocene as a political construct and a tool to constrain the concept of ‘Earth System Governance’ within the social sciences. To quote the author ‘the Anthropocene is political’ and this is indeed the case when attempting to organise disparate and often conflicting bodies into a global community that can guide society to a way of working within nature, but it is also a biological, ecological and geological term and as such a scientific rational to understanding our Anthropocene is required not just a political one.
The writer succinctly demonstrates the interdependence of countries, social groups and global organisations within the modern era along with the intergenerational aspect of a range of social and environmental issues. However it places the Anthropocene as a marketing tool targeted at a political audience rather than a scientific term that denotes a currently unverified chronostratigraphic unit.
It is in no doubt that humans are a significant driving force behind changes to the biosphere and the concept of ‘Earth System Governance’ as described within this paper demonstrates the wide ranging global issues that require consensus.
Regardless of whether it’s worthwhile designating the “Anthropocene” as a new geological epoch (I have my doubts), determining the trajectory of human impact upon the Earth system is important. It provides context for how people see their relationship with natural systems and resources, and can help shape environmental policy and its acceptance by the public. But where to put the onset of this impact – where does the Anthropocene start? The authors of this paper belong to the Institute of Social Ecology at Klagenfurt University, Austria, and take a social sciences approach to the problem. Rather than focusing on physical evidence in the environment, as a geologist might do to delimit a geological epoch, Fischer-Kowalski et al. use a model where human impact is measured as the product of population size, affluence (= energy available per person) and technology, summed over three modes of subsistence: hunter-gatherers, agrarian and industrial. This avoids problems of time lags between human activity and the signature it leaves, and allows the authors to pull apart different driving factors across different societal types.
Using this approach shows a definite shift at around AD 1500: human impact was gradually increasing prior to this, but there is a sharp upturn at ~AD 1500, energy use becomes more important for amplifying the impact of population growth, and a shift from biomass to fossil fuel driven energies enhances this further. While there are problems with this approach – determining energy throughput for long-dead societies will always involve a lot of extrapolation from modern patterns – the authors are careful in stating their assumptions, and going through possible issues with the model itself. It would have been nice to see a comparison between the model output and the empirical evidence though, to help bridge the gap between these two different takes on the same question.
Zalasiewicz, J., Williams, M., Waters, C.N., Barnosky, A.D. & Haff, P. (2014) The technofossil record of humans. The Anthropocene Review, 1, 34-43.
An interesting research article introducing a stratigraphy (technostratigraphy) for and within the Anthropocene, stratigraphic markers are defined as “fossils” left behind by humans (technofossils); for example Iron Age tools from around 1000 BC. The article is driven by the need to:
characterise the deposits, and
date and correlate strata,
of (and within) the Anthropocene in a similar manner to other periods of geological time. By using technofossils from the different stages of homonid technological development Zalasiewicz et al. argue that a chronology can be developed and applied to the Anthropocene concept. Furthermore, Zalasiewicz et al. provide examples of how technofossils, such as pottery and mobile phones, could be used to produce a high resolution (sub-centennial) dating and correlation of strata; so far an unreachable target for other periods of geological time. The paper provides a thought provoking insight the definition of strata throughout geological time, and a novel technique into how this could be done in the Anthropocene.
Miller, C.S. (2014) 520,000 years of environmental change in West Africa. PhD Thesis, Department of Environment, Earth & Ecosystems, The Open University.
CSM (2014)
Abstract:
Global temperatures are predicted to rise by 2–2.5°C by 2065, profoundly affecting the Earth’s environment. The response of ecosystems to past climate fluctuations can inform on how systems will respond in the future. This thesis focuses on Quaternary environmental changes in West Africa, a region important because of its high ecological value and role in the global carbon cycle.
In 2004, the International Continental Drilling Program recovered c. 291m of sediments spanning the last c. 1 Myr from Lake Bosumtwi (Ghana). Pollen, charcoal and nitrogen isotopes (d15N) were analysed from the most recent c. 150m (c. 520 kyr). The latitudinal position and long duration of this core makes it unique for understanding West African monsoon dynamics and vegetation change.
To aid characterisation of the Bosumtwi pollen succession, an atlas of present-day pollen was constructed for 364 pollen and spore taxa.
The pollen record from Bosumtwi reveals dynamic vegetation change over the last c. 520 kyr, characterized by eleven biome shifts between savannah and forest. Savannah vegetation is dominated by Poaceae (>55%) associated with Cyperaceae, Chenopodiaceae-Amaranthaceae and Caryophyllaceae. Forest vegetation is palynologically diverse, but broadly characterised by Moraceae, Celtis, Uapaca, Macaranga and Trema. Low d15N values correspond to forest expansion and these are driven by high lake levels. The timescale indicates that the six periods of forest expansion correspond to global interglacial periods. The record indicates that the wettest climate occurred during the Holocene, and the driest during Marine Isotope Stage 7.
The vegetation and d15N records show a strong response to glacial-interglacial variability between c. 520–320 kyr and 130–0 kyr. Between c. 320–130 kyr there is a weaker response to glacial-interglacial cycles probably related to high eccentricity during the peak of the 400-kyr component of eccentricity, with high eccentricity resulting in greater seasonality and ultimately drier conditions.
The Anthropocene Review is a new journal focusing on the impact of humans on planet Earth through time; information on the latest publications can be found on the associated blog.
Given that much of the research we are interested in relates human-environment interactions in the past we decided to take a closer look at the range of articles being covered by this journal. Our thoughts on seven articles published in the first issue of The Anthropocene Review will appear in a series of blog posts soon. To get started here are a list of the papers we will be covering:
Extracting data from tropical pollen records can be difficult, and time consuming, because of the high floristic diversity. Ecology of the past contributor and PhD researcher Bryan Valencia has developed a method for turning your computer into a tally counter. Bryan’s method allows the easy recording of diverse assemblages, and saves time on data entry. The tally counter can be used to count whatever you like…
With the redesign and refocusing of the blog underway, I’m delighted to announce the launch of our very own “Ecology of the past”YouTube channel. Initially this will host videos produced as part of the Lake Bosumtwi pollen chemistry project, which includes a strong emphasis on impact and outreach activities. The videos are being targeted to a secondary school/sixth form audience, and will demonstrate both how we are doing the research and who we are as academics, highlighting the different roles and career pathways within the team. As time goes on this channel will be a platform for videos from other members of the research group, again showing who we are, what we do and how we do it.
For now, here are the first two videos: a diary of the field trip to Ghana that Adele and I went on last Autumn, and an accompanying piece showing how you too can make your own pollen trap. Enjoy!
William Gosling on:
Ecology of the past 