EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Are peatlands cool humid islands in a landscape?

Fred Worrall1, Ian Boothroyd1, Nicholas Howden2, Tim Burt3, Tim Kohler4, and Ruth Gregg4
Fred Worrall et al.
  • 1University of Durham, Earth Sciences, Durham, United Kingdom of Great Britain and Northern Ireland (
  • 2University of Bristol, Civil Engineering, Bristol, UK
  • 3University of Durham, Geography, Durham, UK.
  • 4Natural England, Humberhead Peatlands National Nature Reserve, Green Tree Warehousing, Tudworth Road, Doncaster, DN7 6BF, UK.

This study proposed that due to their high standing water tables that peatlands would be cold humid islands within their landscape relative to farmland on mineral soils. Long term satellite observation of across England’s largest raised bog (t km2 former raised bog - Thorne Moors, northern England) showed that as the bog was restored the air temperature over the bog decreased by 1.7 oC relative to the surrounding farmland. So this study set out to test this hypothesis with real field observations.

We measured air temperature and humidity at 17 locations along a 7.8 km transect across the Thorne Moors site. Air temperature and humidity were measured hourly for 1 year and supported with spot albedo measurements. The study represented a factorial experiment with respect to sites of measurement; the type of land use (peat vs arable land); and time of sampling over both the seasonal and diurnal cycles. We could show:

  • That although mean annual temperature was not significantly different between arable and peatlands the arable land showed a decreased amplitude to its seasonal cycle – this is the reverse of the expected pattern.
  • The peatland was colder at night and warmer during the day than the surrounding land.
  • The albedo of the peatland was significantly lower than that of arable land showing that vegetated peatland still absorbed more solar radiation.
  • The specific humidity was lower on the peatland than on the surrounding arable land.

The study therefore could show that whilst shrubby vegetation exists over a peatland then energy budgets are more likely to be dominated by the greater surface roughness and lower albedo of the vegetated peatland relative to arable land. Thus, shrub-dominated peatlands will not be a cold humid island in their landscape.

How to cite: Worrall, F., Boothroyd, I., Howden, N., Burt, T., Kohler, T., and Gregg, R.: Are peatlands cool humid islands in a landscape?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2556,, 2020


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  • CC1: thermal properties, Michel Bechtold, 07 May 2020

    Fred, great that you continue to work on the "cooling island" hypothesis. Which role plays the very different thermal properties of the top centimeters of the peat layer compared to the soil of the mineral land? Surface peat (unless very wet then having lower heat capacity and lower thermal conductivity?) is known as insulating layer and maybe heats up quicker than the arable land? Did you look into that as an explanation for the reverse of your hypothesis?