Northern fens: methane flux and climatic change

Abstract

Methane flux from northern peatlands is believed to be an important contribution to the global methane budget. High latitude regions are predicted to experience significant changes in surface temperature and precipitation associated with the 2 x C0 2 climate scenarios, but the effects of these changes on methane emission are poorly understood. A peatland hydrologic model predicted June-August decreases in water storage of between 82 and 144 mm, using as inputs increases in temperatures of 3 °C and rainfall of 1 mm d -1 • These changes translate into a water table drop, relative to the peat surface, of between 14 and 22 cm, depending on whether the fen has a floating or non-floating surface. The 3 °C air temperature increase was predicted to raise peat temperature at 10 cm depth by 0.8 °C. These changes were then applied to relationships derived at a subarctic fen for water table: methane flux: temperature at 10 cm depth. Increased temperatures raise the methane flux by between 5 and 40 % , but the lowered water table decreases methane flux by 74 and 81 % , at the floating and non-floating fen sites, respectively. These results suggest that methane emissions from northern peatlands are more sensitive to changes in moisture regime than temperature within the range of changes predicted for 2 x C0 2 scenarios.

Impacts of climate change on methane emissions from wetlands

“…Another study showed a comparable increase in high latitude emissions in response to warming, but a large reduction should the water table drop [Roulet et al, 1992]. That model's results appear comparable to ours, since our simulations showed increased precipitation at high latitudes along with warmer temperature and therefore an increased emission.…”

Methanogenesis and methane emissions: effects of water table, substrate type and presence of Phragmites australis

“…Changes in temperature and precipitation and the associated effects on water table position will influence methanogenesis and CH 4 emission in a predictable manner (Roulett et al, 1992;Moore, 1994). However, climate changes will also affect plant production and seasonality as well as the area of distribution of P. australis (Matthews, 1993).…”

Experimental drying intensifies burning and carbon losses in a northern peatland

“…In addition to changes in land use practices, warming and increased evapotranspiration associated with climate change will lead to drying of peatlands unless increases in precipitation alleviate soil moisture deficits 16,17 . Whereas projected annual water yields in North American basins vary by region and by global or regional climate model scenarios, higher evapotranspiration from warming generally is expected to compensate for increases in precipitation in some regions and will magnify the effects of precipitation declines in other regions 18,19 .…”