Past Environments
Researches long term changes in climate, ecosystems, and biogeochemical cycles.
About
Past Environments research in Newcastle Physical Geography addresses questions about long term changes in climate, ecosystems, and biogeochemical cycles. Understanding these processes over long timescales is vital to predict the impact of future environmental change on our world. We study sediment records obtained from lakes, peatlands, and oceans by analysing the biological and geochemical remains within them. We work globally, with research sites including Alaska, Antarctica, Greenland, Australia, China, and Europe. Our research encompasses climate change, pollution, environmental archaeology, food web structure, and methane emissions.
Projects
Crannogs: Exploring the environmental impact of our ancestors
Location: Scotland and N-Ireland
Newcastle staff: Dr Andy Henderson, Dr Maarten van Hardenbroek, Dr Helen Mackay
External collaborators: Prof Tony Brown, Prof Pete Langdon, Dr Thierry Fonville (University of Southampton); Dr Nicki Whitehouse, Dr Kim Davies (Plymouth University); Dr Finbar McCormick, Dr Emily Murray (Queen’s University Belfast), Dr Anne Crone, Dr Graeme Cavers (AOC Archaeology Group).
Project outline: Crannogs are island dwellings that were built in lakes and mires. There are 1500 known sites in Ireland and 400 in Scotland. Crannogs can have remarkable preservation because they are largely underwater. This also makes them difficult to study and despite their widespread occurrence little is known about them and their use. Crannogs were constructed from ca. 2500 years ago and used up until the Medieval Period, but little is known about the continuity of their use. The project is designed to answer questions about what were they used for, by whom, and for how long. We analyse dated sediment cores taken close to the crannogs as these contain a continuous record of the past. The sediments contain a wealth of biological (e.g. sedimentary DNA) and chemical remains (e.g. faecal sterols) that tell us about human activities on crannogs, livestock, the surrounding landscape, and our ancestors’ impact on the lake ecosystem.
Acknowledgements: This research is supported by the Arts and Humanities Research Council.
Website: http://celticcrannogs.org/
Lakes and the Arctic Carbon Cycle
Locations: Alaska, Greenland, Norway
Newcastle staff: Dr Maarten van Hardenbroek
External collaborators: Prof John Anderson, Dr Erika Whiteford, Dr Emma Wiik (Loughborough University), Prof Pete Langdon, Prof Mary Edwards, Emma Hopla (University of Southampton), Prof Vivienne Jones, Dr Simon Turner (University College London), Dr Suzanne McGowan (University of Nottingham), Prof Mat Wooller (University of Alaska Fairbanks).
Project outline: Arctic landscapes are changing rapidly in response to climate change. Woody shrubs are expanding northwards into tundra, a process called “greening”. Such vegetation changes influence the cycling of nutrient cycling in soils, including carbon. At a landscape scale, it is uncertain to what extent carbon is stored or released – especially the role that lakes play in this system. This project set out to understand the interactions between known shifts in vegetation and unknown responses in biogeochemical cycling and lake biological structure. Studying sediment records from Alaska, Greenland and Norway will address the role that vegetation composition played in determining lake metabolic state. We analyse biological remains (diatoms, plants, and invertebrates) and geochemistry (bacterial biomarkers, pigments, BSi, XRF, stable isotopes). Results demonstrate distinct and rapid change in lake carbon cycling and productivity as vegetation and soils develop. In Alaska, we found indications for higher methane emissions during the warmer Holocene Thermal Maximum.
Acknowledgements: This research is supported by the Natural Environment Research Council.
Tracking food web structure change with stable isotopes
Location: Flow Country, Scotland, 58° 22' 5.97"N, 3° 40' 0.01"W
Newcastle staff: Dr Maarten van Hardenbroek
External collaborators: Prof Mat Wooller (University of Alaska Fairbanks), Hannah Robson (Wildfowl & Wetlands Trust)
Project outline: Aquatic ecosystems are strongly affected by eutrophication and it is important to assess to what extent they have been altered from a relatively pristine state to reliably model and predict the scope of future change. Traditional palaeoecology studies assemblage change using remains of aquatic organisms preserved in lake sediments. A novel approach uses stable carbon and nitrogen isotopes (δ13C & δ15N) in remains of plants and invertebrates with different positions in the aquatic food web. Quantifying offsets in δ15N (trophic position) and δ13C (energy source) between living organisms gives insights in food web structure and functioning. When applied on remains in sediment cores, it will be possible to study food web structure change over decades to centuries that can be related to known environmental change.
Acknowledgements: This research is supported by the Quaternary Research Association and the Alaska Stable Isotope Facility.
Centennial-scale response of the Indian monsoon to Holocene climate change
Location: Peiku Co, Tibet, 28°55′N 85°35′E
Newcastle staff: Dr Andrew Henderson
External collaborators: Dr Doug Ricketts, Prof Erik Brown (University of Minnesota Duluth, USA), Dr Mario Morellon (University of Cantabria, Spain), Prof Melanie Leng (NERC Isotope Geosciences Laboratory), Prof Jonathan Holmes (University College London), Dr Joe Werne (University of Pitssburgh, USA), Prof Liping Zhou (Chinese Academy of Sciences, China), Dr Torsten Haberzettl (Friedrich Schiller University Jena, Germany), Dr Jesper Olsen (Aarhus University, Denmark)
Project outline: Knowledge of the past variations in the Indian summer monsoon is essential for understanding the monsoon system as a whole and its relationship to other parts of the climate system. Despite existing instrumental data and proxy evidence for variations in the monsoon at sub-decadal to millennial timescales, we still have a poor understanding of how monsoon circulation has controlled long-term moisture over the Asian landmass. This project investigates Indian summer monsoon variability over the past 15,000 years through a high-resolution multi-proxy record (stable isotopes, sediment geochemistry, biomarkers) from sediments in lake Peiku Co, southern Tibet. Peiku Co offers one of the best archives of information of past moisture changes as it lies at the edge of the Indian monsoon rains and is therefore sensitive to changes in monsoon intensity. The isotope record is being used to evaluate changes in the behaviour of the Indian summer monsoon and assesses the relative importance of different forcing factors and wider climatic teleconnections.
Acknowledgements: National Geographic and the Royal Geographical Society supported the expedition to Peiku Co, and NERC New Investigator Grant (NE/H000836), NSF SGER Award (EAR-0732701), as well as the NERC Isotope Geosciences and Radiocarbon Facilities (IP/1043/0508, 1248.1007) have enabled the analytical phase of the project.