Coastal wetland carbon sequestration: impacts of climate change

There is a general consensus that over the last century global climate has undergone change largely as a response to the 40 per cent increase in atmospheric carbon since AD1750.

Plants perform an important ecosystem service by removing some of this carbon from the atmosphere and eventually, through plant matter decomposition, locking it away in the soils, a process known as soil carbon sequestration.

Coastal wetland soils have been identified as one of the largest terrestrial carbon sinks with high rates of carbon sequestration due to the unique processes occurring within the soils related to frequent and regular inundation. However, soil carbon sequestration is influenced by a wide range of factors including inundation frequency, allochthonous/autochthonous carbon sources, wetland progradation/erosion providing the question ‘how is this process responding to climate change?’.

This project identified how carbon sequestration is responding to impacts of climate change such as sea level rise, increased storminess, changes in precipitation/temperature and decreases in sea ice for polar/sub polar areas.

Furthermore, combining historical meteorological data and stable isotope analysis of carbon and nitrogen temporal variations in carbon sources was also identified. Spatial coverage includes a range of coastal wetland types including Arctic salt marshes, northern and southern hemisphere temperate/sub polar salt marshes, boreal Baltic salt meadows and tropical/equatorial mangroves.


Partners

Federal University of Rio Grande, Brazil

Federal University of Sao Paulo, Brazil

Federal University of Paraiba, Brazil

Federal University of Parana, Brazil

State Government of Paraiba, Brazil

National University of Mar de Plata, Argentina

Estonian University of Life Sciences

The project uses soil cores collected from a global network of coastal wetlands including Arctic Norway, east and west Scotland, western and southern England, north, northeast and southern Brazil (including the Amazon estuary), and Argentina. 210Pb/137Cs radionuclide dating provided a geochronology for the cores. Stable isotope analysis of carbon/nitrogen and total organic carbon data was combined with the geochronology to identify how sources and sequestration rates have varied over time.

Utilising historical sea level, precipitation/estuarine discharge, temperature and sea ice records provided important information as to how carbon sequestration rates and sources have responded to past climate variation and thus enabled predictions to be made in future climate scenarios.

Selected publications

Ward, R (2020) Carbon sequestration and storage in Norwegian Arctic coastal wetlands: Impacts of climate change in Science of the Total Environment

Ward, R, Friess, DA, Day, R, MacKenzie, RA (2017)

'Impacts of climate change on mangrove ecosystems: a region by region overview' in Ecosystem Health and Sustainability.