Dr Matt Amesbury
Research Fellow

Research

Research interests

My primary research goal is to better understand the long-term evolution of climate systems, peatland ecosystems and their interactions, with relevance to their response under future climate change. I achieve this through a mechanistic understanding of peatland ecology and functioning and the application of this knowledge to core sediments to address key palaeoclimate research questions. 

My research takes place across different timescales (future, modern, Anthropocene, Holocene) and locations (northern high latitudes, Antarctic Peninsula and sub-Antarctic islands, New Zealand) and uses different proxy (principally testate amoebae and stable isotopes) and statistical methods. Whilst I might think of myself as a palaeoenvironmental scientist, my work is firmly grounded in the present and carried out with an eye to the future. I regard all three of these components as vital parts of my research more broadly and to get the most out of them, I work collaboratively and across disciplines.

My current research is focussed in two main geographical regions: the Southern Hemipshere (SH) high-latitudes and the Arctic.

Firstly, I am interested in the long-term evolution of the Southern Annular Mode (SAM) driven SH westerly winds and their link to the Southern Ocean CO2 sink. The SAM is a principal mode of SH climate variability and one of the main drivers of the Southern Westerly Winds that circle the Southern Ocean and play an important role in how effective the SO is as a sink for anthropogenic CO2. Since about the 1950s, the SAM has undergone a major shift to a more positive phase, resulting in a strengthening and poleward shift of the SWW. However, climate models differ in their ability to reconstruct these instrumental changes and this remains a major uncertainty in future projections of the SAM, with a reduction, reversal or continuation of the recent trend all predicted. Understanding the long-term historical evolution of the SAM offers an important opportunity to feed into improved model projections.

Secondly, I work on the Arctic permafrost peatland response to future warming. Arctic permafrost peatlands are a large and globally important carbon store located in a region predicted with high confidence to undergo rapid future warming. As climate warms, the C locked away in these peatlands, previously rendered inert by freezing, becomes increasingly vulnerable to decomposition. However, release of this C store to the atmosphere may be partly or even entirely compensated by increased productivity in warmer conditions leading to more rapid peat accumulation and C sequestration. How that C is released, whether as CO2 or methane, also depends on the ecosystem state of the peatlands. Understanding the response of these peatlands to past climate in light of the uncertainties around their future is therefore an important research priority.

Separately to these two main research streams, I have recently led two community-driven efforts to compile continental-scale databases of modern peatland testate amoeba data for both Europe and North America, developing standardised transfer functions for both regions.

 

 

Research projects

2019 - 2022: ICAAP (Increasing Carbon Accumulation in Arctic Peatlands). Funded by NERC.

The over-arching aim of the project is to test the hypothesis that changes in the Arctic peatland carbon pool will help mitigate future warming, taking account of both changes in accumulation rates and changes in the extent of peatlands. Demonstration and quantification of an increasing carbon sink in arctic peatlands would represent a fundamental shift in our understanding of the role of the Arctic terrestrial carbon store in mediating climate change. To achieve the overall aim, and test the hypothesis that the Arctic peatland carbon pool will increase with future warming, we will test a series of research hypotheses with a combination of field and satellite data integrated with model simulations. 

2016 - 2019: Holocene evolution of the Southern Annular Mode using novel peat isotope proxies. Funded by the Leverhulme Trust.

The Southern Annular Mode (SAM) is a key control on Southern Hemisphere (SH) climate. It has trended significantly since the 1950s, but its long-term behaviour is poorly understood. Developing reliable SAM reconstructions is therefore critical to understanding SH climate. This project will apply novel palaeoclimate data based on stable isotopes in vascular plant-dominated peatlands to reconstruct SAM variability over the mid-late Holocene. We will test a series of hypotheses concerning the long-term variability of the SAM, its teleconnections with tropical and Northern Hemisphere modes of climate variability and the long-term context of the recent positive trend in the SAM.

2015 - 2016: Understanding and interpreting Eden’s ‘peatland biome’. Funded by the Eden Project and University of Exeter Research Collaboration Fund. 

Our objective was to develop an ecosystem management plan and palaeoenvironmental record for a small peatland located within the Eden estate, supporting its incorporation into the educational and scientific experience of the Eden Project, for both visitors and students. By characterising existing site conditions, including ecohydrological structure and function, this project aimed to understand the present day processes influencing the site. This information contributed to the initial development of an evidence-based and on-going ecosystem management plan. Furthermore, by examining the long-term palaeoenvironmental record preserved in the peat sequence, this project provided a unique ‘history of Eden’.

2012 - 2014: Terrestrial Holocene climate variability on the Antarctic Peninsula. Funded by the NERC Antarctic Funding Initiative. 

You might expect a research project studying Antarctica’s past climate to be using ice cores, some over 4 km thick and hundreds of thousands of years old.  But in the warmer (by Antarctic standards!), more vegetated Antarctic Peninsula there is another archive of past climate just waiting to be investigated.  Banks of moss have been accumulating on islands to the west of the peninsula for thousands of years and it is these we are studying to put the changing climate of one of the most rapidly warming parts of the planet into a longer-term context.  Click here to visit the project website.

2012 - 2013: Developing a novel proxy for Southern Hemisphere Holocene climate change: stable isotope analysis of restiad peat cellulose. Funded by NERC.

Previous studies of changing isotope ratios from peat bogs have used a particular type of moss, called Sphagnum, from which to derive their measurements.  This is effective, but is also limited, both to geographical areas where Sphagnum occurs and also to the parts of a core where Sphagnum is present; nobody wants gaps in their record.  We are addressing these two issues by testing the applicability of studying isotopes in a different type of peat that is found in regions where Sphagnum is less common.  In the Southern Hemisphere, bogs are generally dominated by higher, or vascular, plants rather than mosses; these are plants that can actively control the movement of water and nutrients in their tissue.  Bogs dominated by higher plants are widespread globally, but because of the differences in biology between them and mosses, we can't be certain that the isotope method is applicable without rigorous testing.  We are using bogs in New Zealand to perform further tests.  If we can demonstrate that the isotope method can be applied to this peat type, the method would be applicable over a much wider geographical area and we will be able to address pressing research questions about past climate change more so than at present.  Read our collection of blogs on the project here.

2010 - 2012: PRECIP (Palaeo REconstruction of ocean-atmosphere Coupling In Peat). Funded by NERC.

Using a transect of peatlands in Maine, USA and the Atlantic Provinces of Canada, we aimed to reconstruct the spatial-temporal pattern of moisture balance changes associated with past variability in the Gulf Stream and Labrador Current. These Holocene reconstructions were be generated at (multi-) decadal to millennial time-scales and used to test a set of hypotheses concerning the relationships between ocean thermohaline variability, atmospheric circulation and terrestrially-based palaeoclimate responses.

 

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