How an archaeologist learned to love climate research

For twenty years Albert Hafner was involved in archaeological digs under water and in bogs and ice. In his second career as professor of archaeology what attracts him most is research - and for this he is more than happy to team up with climate experts.

Most archaeologists dream of pottery shards, but Albert Hafner, professor of prehistoric archaeology, has a soft spot for wooden items. For example, hanging in his office is a ring the size of a dinner plate, woven from twigs. It comes from a stable in the Simmental, where this kind of wattlework was still used in building fences until quite recently. What is astonishing about this object is that a practically identical ring dating back 5000 years was found on the Schnidejoch in the Bernese Oberland. "We are looking at a tradition of fence building using the same method over thousands of years," marvels Hafner.

It is not only the style of wooden tools that fascinates Albert Hafner; as an archaeologist, he has a very practical reason to be interested in objects made of wood: thanks to dendrochronology, a method that exploits annual tree rings, they can be dated very precisely. But for this to work, the wooden finds need to be more or less intact, and this only occurs when items have been preserved in the right natural conditions, for example, in underwater sedimentation or in glacier ice. Hafner focussed on precisely these questions over the 20 years of work for the Bern cantonal archaeological service, where he ended up as head of underwater and wetland archaeology. His office was the Von Rütte manor on Lake Biel, with its associated diving centre and dendrochronology laboratory, located at one of the most important prehistoric pile dwelling sites in Europe.

Hafner's first contact with the Oeschger Centre came in connection with the spectacular finds on the Schnidejoch, a crossing point between the Bernese Oberland and the Valais lying 2756 metres above sea level. As the glacier retreated, it left uncovered a total of 900 objects. These ice finds sparked a lot of interest not only among archaeologists, but also among the climate scientists of the OCCR. It enabled them to draw up the most precise reconstruction yet of glacier fluctuations in the alpine area in prehistoric times. In 2008 the two disciplines jointly organised a scientific symposium entitled "Ötzi, Schnidi and the Reindeer Hunters: Ice Patch Archaeology and Holocene Climate Change" - the first of its kind anywhere in the world.

Since then Albert Hafner has himself become part of the Oeschger Centre. In 2012 he was appointed full Professor of Prehistoric Archaeology at the University of Bern, and is currently director of the Institute of Archaeology as well as Adjunct Researcher at the OCCR.

As has been clear at least since the joint conference, archaeology and climate research have a lot in common. After all, swings in the climate affect human beings, and conversely, human activities have an impact on the climate. "We should not underestimate the early influence of human beings on the environment," says Albert Hafner. "As long as they merely hunted, the impact was small, but it increased once humans started farming, burning down the forests and opening up the landscape." On the other hand, too little attention has so far been paid to the way the climate influenced great historical processes like migration, he believes.

But on a small scale the impact of climate change on human beings in the past is clear to see. For example, the settlements on the shores of lakes in the Swiss plateau were destroyed over and over again by rising water levels ? and since this protected them from decay, they are now valuable archaeological sites. Hafner believes that the reason for the periodic fluctuations in the lake levels could have been changes in the climate.

But it is not only with regard to content that archaeology and climate research complement each other. In a joint research project with the OCCR group for Terrestrial Paleoecology Albert Hafner wants to draw on his colleagues' methodological know-how. "Lake sediments store both environmental and cultural information," he explains. "We want to exploit this in order to gain a better understanding of the way the culture evolved during the Holocene. We can't do that using our archaeological methods."

The focus here is on information to be gained from two small lakes not far from Bern, the Burgäschisee and the Moosee. It is true that there are half a dozen archaeological sites in close proximity to them, but there are gaps in what these reveal of the settlement history of the last 10,000 years. Paleoecological analyses of the lake sediments will make it possible to understand the impact of human activity throughout the Holocene epoch. The layers of deposits found in drilling cores contain a large amount of evidence of such activity, for example slash-and-burn land clearance and erosion caused by the people living in the villages around the lakes.

By combining their methods Albert Hafner and paleoecologist Willy Tinner want not only to show when the first settlements were established, but also to find out whether their contacts oriented them eastwards or westwards. The fact is that even back in prehistoric times people living in what is now the Swiss plateau region were oriented towards different cultural areas. The origins of the "rösti ditch" ? the divide between German and French speakers in Switzerland ? evidently go back a long way.