UK Nature and Environment

As well as being an important habitat for wildlife, the sites are able to sequester CO2 from the atmosphere, much in the way that forests or peat bogs do. But the UK’s salt marshes are at risk. As sea levels rise due to global warming, saltmarshes can become inundated by seawater, effectively drowning the sites. Saltmarshes have also been lost as land is claimed for agriculture. Researchers in Yorkshire, therefore, are now warning of the major impact that future losses of salt marshes could have for both carbon emissions and biodiversity. “Salt marshes provide a whole range of different benefits to the natural world and to human populations,” says Ed Garrett, assistant professor in Physical Geography in the Department of Environment and Geography at the University of York. “This ranges from being an effective flood-defence mechanism – storing water during flooding – to reducing the energy of incoming waves, thereby reducing coastal erosion. They provide a biodiversity hotspot as well, and are much more biologically productive than some other coastal environments. “But salt marshes are much more rare than they used to be. We now have about 450 sq km, but if we go back to the mid 1800s we had about 3,000 sq km of salt marsh. “The Humber is really depleted in its salt marsh area. Only two per cent of the Humber estuarine area is currently salt marsh, and that's against a national average of six per cent of estuarine areas, so the Humber is much lower, there are only a few small fragments left.” Garrett was one of several researchers to work on a paper published late last year on the role of saltmarshes in storing and sequestering carbon. The research found that the UK’s salt marshes currently store around 5.2 million tonnes of carbon. Should these habitats be lost, however, that carbon is at risk of being released. “When we’re talking about protection of saltmarshes, the biggest thing that could be done is to act on the climate crisis and address the causes of current sea level rise,” says Garrett.