Upscaling of greenhouse gas emissions from freshwater wetlands

The single most important global environmental and policy concern in the 21st century is that of human-induced climate change, with an urgent need for quantitative information about the sources and sinks of the responsible greenhouse gases (GHGs); indeed, the international agreements from the 2015 Paris climate conference (COP21) emphasised the need for "the best available science" to aid in reducing atmospheric GHG growth rates. Unfortunately, there are serious gaps in our quantification of some major global natural sources and sinks of GHGs, and northern lakes and wetlands represent one such on-going debate. These limitations to our knowledge are largely a reflection of the necessary technologies for making the measurements. The two basic methods for quantifying GHG fluxes are called 'chamber' and 'eddy covariance (EC)' flux techniques; the former is a well-established technology which involves placing a small chamber over a land or water area and monitoring the gas concentration changes inside the chamber over time. The second, EC approach, relies upon summating small concentration differences in upward and downward air gusts (eddies) to derive a net system flux. Both systems Have their failings and advantages; for example, chamber systems only measure over small areas and are expensive to build and operate, whilst EC systems can provide a flux for a large area (km2) but cannot resolve down to locate point sources at the 'hotspot' or experimental plot scale. Under recent NERC funding, scientists at York have developed a totally new measurement approach, based on the technique used to move overhead cameras at major sports events. The system can rapidly place a chamber, or piece of heavy equipment, anywhere in a large measurement arena, to an accuracy of a few mms, achieved using precision-controlled winches, under the automatic control of a pre-programmed computer, and working continuously. The system can therefore provide highly replicated measurements in time and space, overcoming many of the problems of existing methods. The current grant is targeted at establishing such a system at one of the leading, and best equipped, GHG monitoring sites in the world (Lake Foljesjon, Sweden), where there are major unresolved questions about the key sources of the large GHG fluxes coming from this inland lake. The UK team have been invited to work collaboratively at the site because of the inherent difficulties of working in this terrain. The resulting international team will measure detailed GHG exchanges from the lake, identifying whether specific vegetation types, open water, specific sediment types etc. are the major hotspots for the observed gases fluxes (e.g. methane). Our roving equipment will work day and night, under all weather conditions, and will be unique throughout the world supported by full access to the existing sophisticated infra-structure (e.g. 3 phase electricity at the site, field accommodation and vehicles, local engineering support, access to existing datasets) as well as state-of-the-art sensors (e.g multi-spectral scanners, precision lasers) for test 'flying' on the head of our novel system, enabling unprecedented and accurate data about the structure of the lake and it's vegetation. If we successfully prove the technology in this difficult environment then similar systems could well be adopted around the world (e.g volcanos, agricultural research) leading to entirely new, UK-based, environmental monitoring technology and expertise. The International Opportunities Fund (IOF) scheme is designed to enable NERC-supported researchers to build long-term partnerships with overseas scientists, add value to current NERC-funded science; this is precisely the aim of the current work, with the resulting collaboration addressing a key global question neither group can answer alone, and initiating a potentially long-lived dovetailing of two highly complementary research groups.

The work undertaken as part of this project will directly benefit both the scientific and policy making communities. Within the scientific community the research will be of particular interest to various sub groups, including, inter alia i. ecosystem scientists (for example, the Swedish groups involved in the SITES programme (http://www.fieldsites.se/en/)) ii. GHG flux modellers iii. The eddy covariance (EC) community and iv. Industrial manufacturers of EC equipment, e.g. Campbell Scientific.
i. The continuous flux measurements that this project will produce will be made at both the ha and < 1 m2 scales and will provide unprecedented detail about the processes driving GHG fluxes, especially CH4, from boreal lakes. This will significantly further our understanding of GHG emissions and how they contribute to climate. ii. The high frequency flux data, allied to a comprehensive suite of ancillary environmental data will greatly improve the accuracy of process driven models for explaining CH4 emissions. The shortcomings in modelling CO2 and CH4 flux have frequently been highlighted in the literature, and the team from University of York has a strong track record of working closely with leading modellers Prof Mat Williams of the University of Edinburgh, Prof Pete Smith of the University of Aberdeen and Dr Pete Levy (Centre for Ecology and Hydrology, Edinburgh) on the ELUM and GREENHOUSE projects. We have consulted Professor Williams during the experimental planning of this project and we will continue to conult the GREEBHOUSE team to ensure that the data produced will be in the most useful format for informing future CH4 and CO2 models (see letter of support). iii. If successful, the deployment of roving EC will revolutionise this technology and will enable application of EC at the plot scale, facilitating monitoring of manipulative experiments by EC for the first time, opening a whole new field of research. The methods developed here will be applicable to experiments on multiple land uses, including agriculture (e.g. crop trials), forestry, or a combination of terrestrial and aquatic systems. iv. SkyLine3D was showcased for the first time at EGU16 in Vienna, resulting in nearly 100 groups and individuals expressing concrete interest in the availability of this technology. Amongst the interested parties were several commercial manufacturers of analytical equipment, including the UK firms Delta-T and ADC, and US-based Campbell Scientific and LI-COR.
With accurate reporting of GHG inventories a pivotal element of international treaties on climate change (UNFCCC, Kyoto), increasing the accuracy of models will lead to better informed policy makers and thus improve our ability to mitigate GHG fluxes. Policy makers- better informed regarding national GHG inventories.
The nature of the ecosystem-scale processes which will be in investigated in this programme have a global impact which will endure for generations. With accurate reporting of GHG inventories a pivotal element of international treaties on climate change (UNFCCC, Kyoto), increasing the accuracy of models will lead to better informed policy makers and thus improve our ability to mitigate GHG fluxes. Policy makers- better informed regarding national GHG inventories.