| I ’M A geographer |
Brian Chase is a US geographer who studies ancient hyrax latrines in southern Africa in order to build up a picture of what the climate has been doing there over the past 50,000 years. Currently based in France, he spends about three months a year searching for fossilised rodent toilets in Namibia, Angola and South Africa. He talks to Olivia Edward about why the ability to rock climb is an essential part of his job and how his research challenges current beliefs about the greening of the Sahara
I didn’t get my undergraduate degree until I was 27. It just took me a really long time to figure out what I wanted to do. I tried environmental design, spent a little while being a potter, and trained as a mountain and whitewater-rafting guide. Overall, I spent about six months each at several universities. My parents were in complete despair.
Then I discovered geography. And I thought, ‘This is fantastic.’ I had always loved reading National Geographic – all those amazing stories about places and people – but I never thought that it was something I could go and study. In the USA, people just don’t study geography, or at least not until university level.
My first Masters looked at how people and environments co-evolved over time. One aspect that niggled me was the lack of depth in terms of time. I found myself wanting to look at the impact that humans have had on the landscape over thousands of years, or even tens of thousands of years, so I started getting into the whole ‘palaeo’ side of things – the study of the prehistoric side of life.
I focused in on climate science because it’s an aspect of geography that’s brushed aside. People say, ‘The climate has always been like this…’ or, ‘It was a deteriorating climate, which forced people to…’. It’s like storytelling; it’s so ‘broad brushstroke’. There’s no quantification of these descriptions, or explanation of how or why these changes in climate occurred.
I’m now trying to understand and unravel the environmental history of the southern African subtropics over the past 200,000 years or so. The subtropics are very understudied because they don’t have the archives of Western Europe, such as peat bogs and lakes, where sediment accumulates. But drylands are very important because they’re at the interface of the world’s major circulation systems.
I study the latrines of rock hyraxes [small African rodents]. These animals shelter in the rocks and like to defecate and urinate in particular places. They carry on doing it until the pile of mess they’ve created is so big they can’t fit into the cave any more. By that time, the midden, as we call it, can be thousands of years old, and much of it will have solidified.
The biggest one we’ve collected was 75 centimetres tall and spanned 28,000 years. They’re often really tough to get out. I climb up to them or abseil down to them with an angle grinder and cut them out. They’re rock solid, although the upper layers can just melt when you touch them. I used to climb up and reach up to grip onto them and find I was slipping. It was scary. Now I carry an ice axe to thrust into the middle of them and pull myself up.
Once we get a midden back to the lab, we can analyse its microfossils, pollen and phytoliths (little silica bodies that develop in plants), which gives us a nice picture of past vegetation. We also look at the carbon and nitrogen, which tells us about vegetation and humidity levels.
Our most interesting discovery so far is about the greening of the Sahara during the early Holocene, when hippos were swimming around in what’s now desert. People have always thought that this was because the tropical moisturebearing systems shifted north and left the south drier. This idea is so widely accepted that people don’t even cite the study any more. But it was based on one data point in southern Africa. Instead, we’ve found that the Southern Hemisphere responds in precisely the same way as the Northern Hemisphere at precisely the same time. Essentially, this means that the tropical wet area expands and contracts rather than shifts.
It’s really important that this information is fed into the models predicting future climate scenarios, because if they’re not simulating past environments terribly well, then you have to start taking their future scenarios with a grain of salt.
The amount of data we currently have, compared to the questions we want to answer, just isn’t enough. Sometimes it’s daunting, but at the same time, it’s a challenge, and you feel the work you’re doing is really useful. I’m not refining some little piece of a climate curve for Western Europe, I’m helping to create the story of what happened in southern Africa, so I feel as though I’m making a significant contribution.
1970 Born in Providence, Rhode Island, USA
1986–89 The Cambridge School of Weston, Weston, Massachusetts
1997 BA in geography, Portland State University, Oregon 1998–99 MA in geographic education, Prescott College, Arizona
2001–02 MSc in environmental archaeology and palaeoeconomy, University of Sheffield
2003–04 Research assistant, University of Cape Town, South Africa 2006 DPhil in physical geography and Earth system science, University of Oxford 2006–present Research associate, University of Cape Town, South Africa 2010–present Chargé de Recherche 1ère classe, CNRS, Institut des Sciences de l’Evolution, Université Montpellier 2, France
82 www.geographical.co.uk FEBRUARY 2011