Can megafauna shift the carbon and surface radiation budgets of the Arctic?

Lead Research Organisation: University of Oxford
Department Name: Geography - SoGE


One of the key challenges and concerns when considering 21st century climate change is the identification and avoidance of positive feedbacks (which may lead to "tipping points") in the biosphere carbon cycle, where parts of the biosphere respond to climate change by becoming major emitters of greenhouse gases to the atmosphere. High latitude tundras are particular regions of concern, as they hold substantial reserves of permafrost carbon -especially the Yedoma soils of northeast Siberia and north-western North America- and are also substantial sources of atmospheric methane. Although these regions are now dominated by wet shrub- and moss-dominated tundra and forest-tundra vegetation, there is evidence that throughout Pleistocene glacials and interglacials the region was dominated by highly productive grasslands ("the mammoth steppe"), the most extensive land biome on Earth, which supported high animal biomass despite the cold temperatures. SA Zimov (1995, 2012) proposed that the mammoth steppe was created and maintained by the abundance of large herbivores (e.g. bison, horses, rhinoceros, mammoths), and that it was the extinction of these megafauna, most likely caused by the spread of human hunting populations into the Arctic in the Late Pleistocene and early Holocene, that led to the collapse of the mammoth steppe and its replacement by the current low productivity wet tundra vegetation. Moreover, he proposed that the introduction of a guild of megafauna herbivores with diverse feeding strategies such as horses and bison into the Arctic could lead to the rebirth of this lost cold high-latitude ecosystem. This would stabilise soil carbon reserves and act as mechanism to diffuse the threat of a carbon cycle positive feedback in the permafrost regions. In 1996, SA Zimov established the "Pleistocene Park" in northeast Siberia to demonstrate the feasibility of megafaunal introduction in the Arctic and its potential to shift ecosystem states from tundra to grassland. While the experiment has succeeded in initiating a vegetation shift from wet tundra and forest-tundra to open, grass-dominated landscapes, to date no detailed and systematic monitoring has been implemented to test the core components of SA Zimov ecosystem-climate hypothesis. These outline how such an ecosystem shift would affect land surface radiation and water budgets, soil and surface temperature and moisture, and net carbon balance. Here, we propose to work closely with Sergey and Nikita Zimov to conduct the first detailed evaluation of the above hypotheses, using state-of-the art techniques to assess the carbon, water and radiation budgets of the land surface with and without megafaunal rewilding. We will measure the net flux of carbon and water from the ecosystem to the atmosphere using flux measurement towers and soil CO2 efflux measurements, coupled with detailed measurements of soil and atmospheric conditions and energy balance, and scaled using drone-based maps. Detailed observation of ecosystem and microclimate processes in the field will provide parametrisation of key aspects of the system in two Earth System Models (BNU-ESM & CAS-ESM), allowing exploration of the potential impacts of different possible scenarios of high-latitude biome shift on planetary climate and biogeochemical processes. This work would provide unique mechanistic insights into the present, past and potential future ecosystem and climate dynamics of large parts of the Arctic


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Description 2024 - PRE-IMPACT: GRANT PROGRESS GRANT PAUSE, PIVOT TO GREENLAND, TRANSFER TO SCOTT POLAR RESEARCH INSTITUTE, UNIVERSITY OF CAMBRIDGE, FIRST FIELDWORK A. 01/03/2022 - 24/04/2023: The award was suspended due to the Russian invasion of Ukraine, which prevented proceeding with the originally planned fieldwork location in NE Siberia. A 2-month NCE was automatically awarded due to the need to change the project on 24/10/2023. B. Upon approval of pivoting the project to a new field site location in Greenland, the award was reactivated on 24/04/2023, however this was not communicated by NERC to the PI until 10/08/2023. C. July 2023: PI Marc Macias-Fauria accepted a new position at the Scott Polar Research Institute, University of Cambridge (start date 01/01/24). This further delayed the recruitment and appointment of researcher. D. 24/10/2023. As part of my negotiation with the University of Cambridge, I obtain a top up for the budgeted PDRA linked to this project, so that we can employ a more senior researcher. NERC UKRI agrees with this and allows the PDRA to be advertised and budgeted using the funding on the grant to part fund the PDRA with a top up from the University of Cambridge. E. March 2024. Workshop organised in Kangerlussuaq, Greenland, with the participation of the Greenland Institute of Natural Resources and members of the Qeqqata Commune, West Greenland, amongst other researchers. F. 11/04/2024. The Research Associate linked to the project (Dr Jeff Kerby) starts his job at the Scott Polar Research Institute, University of Cambridge (with a delay linked to processing visa application as the researcher is a USA national). G. 29/04/2024. The award is accepted by the University of Cambridge and its start date of 11/03/2024 is confirmed. H. As a result, and following advice from Helen Armstrong (NERC UKRI), we applied for a 20-month NCE, with revised end date of 10/03/2027 to enable the researcher employed on this project - Dr Jeff Kerby - to deliver the 36m schedule of work. I. May and June 2024. first fieldwork in the research site of Kangerlussuaq, Greenland.
First Year Of Impact 2024
Sector Environment
Impact Types Cultural



Policy & public services

Description Building synergies to explore the role of herbivores in ecosystem processes and biogeochemical cycling West and South Greenland.
Amount £17,000 (GBP)
Funding ID NERC United Kingdom - Greenland Arctic Research Bursaries Scheme. 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 03/2023 
End 04/2024
Description Collaboration with the Greenland Institute of Natural Resources - 
Organisation Greenland Institute of Natural Resources
Country Greenland 
Sector Public 
PI Contribution We are doing research in the Qeqqata Commune on the role of herbivores on tundra vegetation, which is relevant to the Greenland Institute of Natural Resources. We organised a workshop - see extra funding - in March 2024, attended by staff at the Greenland Institute of Natural Resources, most notably by Dr Mathilde LeMoullec, Terrestrial ecologist at the Institute, where we discussed collaboration avenues. In June 2024, we conducted a scoping trip to possible sites in the vicinity of our sites for plots to be established by the Greenland Institute of Natural Resources.
Collaborator Contribution Staff at the Greenland Institute of Natural Resources have attended our workshop, come with us to the field in Greenland, and discussed collaboration options.
Impact March 2024. Workshop in Kangerlussuaq, Greenland. June 2024. Join field trip close to Kangerlussuaq, Greenland.
Start Year 2024