Climate protection left high and dry – moorland drainage.
The consequences of drainage: moorland is irreversibly damaged, biodiversity is lost and climate rescuers become climate killers. The problem is that the conventional use of moorland inevitably leads to its destruction. This is because the water table must first be lowered, which in turn alters the hygroscopicity and conductivity of the peat. It comes into contact with oxygen and mineralises, not only releasing smaller amounts of the even more harmful greenhouse gas N2O (nitrous oxide or ‘laughing gas’), but also huge amounts of climate-damaging CO2.
The drainage-induced aeration of the peat soil oxidises the carbon sequestered there, causing huge amounts to be released back into the atmosphere as CO2. For every 10 cm the mean water table is lowered, approximately five tonnes of additional CO2 are released into the atmosphere per hectare, per year. The widespread use of drained moorland as arable land and grassland in Germany causes ongoing CO2 emissions of 40 and 30 tonnes per hectare, per year respectively.
In Germany alone, approx. 45 million tonnes of CO2 escape from drained moorland every year. This equates to 5% of the total annual emissions in Germany and almost 40% of emissions from German agriculture.
Moorland also suffers from the effects of climate change and excessive nitrogen levels in the groundwater. Longer periods of drought and heat cause groundwater levels to drop. Extreme rainfall events also present problems, since the moors can no longer absorb the elevated water quantities. Both climate phenomena thus contribute to moorland drainage. Nitrate contamination of groundwater is due to nitrogen oxide emissions from combustion engines and, above all, to fertilisers containing high levels of nitrates. As a result of the process known as eutrophication, nutrient-seeking organisms displace the existing biocenoses, which also promotes drying out. In addition to this, the nitrogen output during droughts causes peat to mineralise much faster, thus releasing CO2.