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Tales from the field: reconstructing past warm climates

The warmest period of the past 65 million years was the early Eocene epoch (55 to 48 million years ago). During this period, the equator-to-pole temperature gradient was reduced and atmospheric carbon dioxide (pCO2) was in excess of 1000ppm. The early Eocene has received considerable interest because it may provide insight into the response of Earth’s climate and biosphere to the high atmospheric carbon dioxide levels that are expected in the near future as a consequence of unabated anthropogenic carbon emissions (IPCC AR4). However, climatic conditions of the early Eocene ‘greenhouse world’, are poorly constrained, particularly in mid-to-low latitude terrestrial environments (Huber and Caballero, 2011).

I recently spent a week in eastern Germany (Schoeningen, Lower Saxony) sampling an early Eocene lignite seam (Fig. 1). Lignite is a type of soft brown coal that is an excellent terrestrial climate archive. Using palynology, organic geochemistry, coal petrography and climate models, we will try to reconstruct the terrestrial environment of the early Eocene and provide insights into future climate change. 

Fig. 1. A view of the mine with Dr. Volker Wilde on the far right for scale.

During this trip, we were sampling at the base of the mine beside a very large and very dusty bucket-wheel excavator (Fig. 2). A bucket-wheel excavator is a continuous digging machine over 200m long and dwarfs the large NASA Crawler that transports space shuttles to launch pads. Once the lignite is removed, it is placed upon a conveyor belt and transported immediately to a nearby power station. Unfortunately, the Schoeningen lignite will not last forever and the town will have to consider other energy sources (e.g. wind).

Fig. 2. A bucket-wheel excavator at Schoeningen mine.

Our sampling technique was less impressive yet equally effective. All we required were hammers, chisels and pick-axes (Fig. 3.). After a long day of sampling, we were taken to a very special outcrop at the top of the mine. The exposure contained well-reserved palm tree stumps from the early Eocene and provide evidence for white beaches, tropical plants and endless sunshine on the German coastline. An ideal holiday destination!

Fig. 3. Dr. Marcus Badger sampling Main Seam in high resolution.

Following fieldwork we were taken to the new Schoeningen museum containing, amongst other artefacts, the Schoeningen Spears (Fig. 4). The Schoeningen spears are 300,000 years old and are the oldest human weapons in existence. The spears were found with approximately 16,000 animal bones, amongst them 90% were horse bones, followed by red deer and bison. It has been proposed that these spears were the earliest projectile weapons and were used for 'big game hunts'. Although this theory has been questioned, it remains one of the worlds most exciting archaeological finds.

Fig.4. The Schoeningen spears. Most were preserved fully intact.

Now we are back in Bristol its time to start processing our samples so we can understand what the early Eocene terrestrial climate was like. Watch this space!

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The trip was in collaboration with members of Bristol (UK), Royal Holloway (UK), Gottingen (Germany) and Senckenberg (Germay).

This blog was written by Gordon Inglis (http://climategordon.wordpress.com).

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