Tools to unlock Palaeogene climate records from high-latitude coal seams

Terrestrial palaeoclimate records are generally challenging to obtain due to the dynamic changes of landscapes, and ubiquitous erosion on land. Deep-time palaeoclimate proxies are typically retrieved from marine sedimentary records of calm depositional environments; these, however, do not capture the land surface-atmosphere interaction, which forms a crucial component of the global carbon exchange. This is particularly true when using palaeoclimate analogues for the future climate state, where land surface temperature, hydrology and vegetation interaction will have direct impact on land surface conditions.

 

The Palaeocene Firkanten Formation on Svalbard, Arctic Norway, holds up to 5 m thick coal seams, representing extensive peatlands in a Boreal climate, at c. 75 degrees N palaeolatitude. Deposition in the high Arctic in a high atmospheric CO2 hyperthermal world, makes this record a highly relevant analogue for the currently rapidly warming Arctic. Undisturbed coal samples from three different coal mines provide a high-resolution archive of C-isotopes, inorganic dust, pollen and coal macerals. In the Svalbard Warm Arctic Palaeoclimate (SWAP) field laboratory we are testing dC13 as a proxy for water stress in the peatland and comparing the potential palaeohydrology proxy to XRF data of inorganic particles as proxies for wind distribution and/or dry/wet conditions. Currently, our samples comprise the dC13 record, preliminary pollen analyses, XRF of inorganic particles, whereas future work will target coal macerals as indicators for the temperature of forest fires, and comparison with carbon exchange in modern Arctic records. We will discuss the robustness of these proxies for the deep-time peat record, and the implications for future climate models for the Arctic land surface in a warming world.