This week’s post is contributed by Matthew Pope, a member of the Open Quaternary Editorial Board and researcher at University College London where he studies the ways in which humans have adapted to north European environments during the Quaternary.
The publication of the IPCC synthesis report on the 1st November 2014 gave a warning we’d heard before but in starker terms that even the best efforts by lobbying groups couldn’t blunt:
“Many aspects of climate change and its impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped. The risks of abrupt or irreversible changes increase as the magnitude of the warming increases…. Global mean sea-level rise will continue for many centuries beyond 2100 (virtually certain).”
– IPCC Synthesis Report [PDF], Section 2.4
The apparent inevitability of substantial climate change and environmental impact even with a dramatic reduction in carbon consumption puts us on notice that this century’s challenge will not only be the engineering of carbon-neutral global economy, but the significant reengineering of human settlement in vulnerable coastal areas. The World Ocean review report Living with the Oceans states that currently 200 million people worldwide live within 5m of sea level, that by 2100 this is estimated to rise to 500 million, and the continued growth of urbanism in Asia and it’s knock on effects with groundwater subsistence in coastal cities will exacerbate the threat to human populations.
From my own perspective I find these reports unsettling. First as a father of three children, two of them born in the late 1990’s and so perhaps part of first tricentennial generation, they will be the ones to finally make the call on our current predictions and historically judge our responses. As a researcher interested in long term climate change across northwestern Europe, it is unnerving to see the possibility of climate and sea level changes beyond those observed during a record extending back over a half a million years. Indeed from an evolutionary perspective, seeing C02 levels exceed those which have been observed during the entire history of the genus Homo (Bartoli et al., 2011), we should be on guard that we are changing the fundamental conditions which have given rise to our species.
But it’s in my other role as part of commercial archaeology that I feel that we as a discipline might be able to play a part in responding to the challenges of global change. Geoarchaeology, in Europe and across many parts of the world, is firmly embedded in the construction industry and as such a large volume of work takes place close to sea level. Not only does this work involve assessing sites ahead of residential, industrial or infrastructure projects in coastal areas but, increasingly, as part of engineering projects designed to protect communities and infrastructure from the sea. Globally we can expect to see, if the IPCC predictions are correct, an ever increasing investment in coastal protection as we pass through the 21st century. Generally our work is framed in terms of heritage protection, assessing the record of landscape and environmental change to augment or enhance cultural archaeological work being undertaken by our colleagues. Generally the work is well provided for but sometimes it feels as if the geoarchaeological component is a welcome add on or enhancement, scientific support to the front line of rescue archaeology.
But perhaps we are looking at it the role geoarchaeology plays in the wrong way, and perhaps we are missing an opportunity to play a localised, constructive role in helping to direct how coastal communities develop in the coming century. Ultimately the resource we are tasked and paid to look at provides an archive of coastal geomorphological processes and their intersection with wider sediment systems and human habitation. The records I might deal with on the south coast of Britain not only bracket long term sea level change through the Pleistocene but have the ability to document recent Holocene change: infilling of coastal inlets, formation of gravel bars, the timing and incidence of flood events/storm surges. It strikes me that while geotechnical studies are at pains to test the solidity and suitability of a sediment body for foundation design, there appears little explicit consideration in design of time depth; which can state when that sediment body formed, how prone has it been in the past to flooding/erosion, and what wider sedimentary systems have an overall control on its existence. While national agencies may be best placed to deal with these issues regionally, our discipline has the ability not only to feed precise data on a given location into these considerations but also to develop risk assessments with temporal depth for much wider areas.
I leave you with an example from north west Europe to think about. Last month saw the 1000 anniversary of a coastal flooding event which affected a large part of the English Channel and Severn Estuary. The event was recorded in the Anglo-Saxon Chronicle for 1014:
“This year, on the eve of St. Michael’s day, came the great sea-flood, which spread wide over this land, and ran so far up as it never did before, overwhelming many towns, and an innumerable multitude of people.” And also by the chronicler William of Malmsbury: “A tidal wave grew to an astonishing size such as the memory of man cannot parallel, so as to submerge villages many miles inland and overwhelm and drown their inhabitants.” While of great historical interest, I’d argue that there is also a moral imperative for us to understand the likely origin, distribution and effect of past flooding events. Ground-truthing a single event from the historical record helps us to bracket the range of past observable effects and to prepare adequately for their possibility in the future. And if, during the 21st century, we continue to build communities and businesses in parts of the landscape likely to be at risk from the effects of climate change, is there not also a clear moral obligation to assess the ground on which they are built for past resilience to flooding or erosion?