Farm animals are bad for the climate, cows are climate killers - these theories are often repeated in the debate on reducing CO2 emissions. However, scientists from the University of Oxford, the University of Reading, CICERO Oslo and the Victoria University of Wellington have come to a clear conclusion in a new joint study: a constant emission rate of short-lived greenhouse gases, such as methane, does not lead to any change in global warming. This means: a cattle herd with constant methane production does not contribute to further warming of the atmosphere. Rather, an increase in the methane emission rate causes warming, and a decrease in the methane emission rate in turn causes cooling. This was not accurately reflected with the conventional conversion of methane emissions to CO2 equivalents used in international climate reporting. The new conversion measure is now abbreviated as CO2* or CO2w.
The results of this study are confirmed in a recent research report by the Austrian Agricultural Research Institute HBLFA Raumberg-Grumpenstein. The starting point for modelling the warming effects of methane and nitrous oxide from agriculture was precise livestock data from the early days of industrialisation. For Austria in 1890, methane emissions are very similar to today, also due to the larger number of draft animals in the past. The total effective warming effect summed over the time axis since 1890 was very small and close to net-zero climate neutrality because of the rapid decomposition of methane and the subsequent reuptake of carbon by agriculture.
These results are related to the release of methane from different origins: Fossil methane from natural gas production is converted to CO2 after eight to twelve years. In the process, a total of more carbon is transferred into the atmosphere than can be bound in soils - this in turn leads to further warming of the Earth's surface. Methane from livestock farming, using existing biomass, also enters the atmosphere and is converted into CO2 after a few years, but the corresponding carbon is again bound by plants and soils to the same extent. However, this only works if the carbon sinks are not impaired in their function, i.e. if soils are not further sealed or drained or forests are not cut down.
The scientists at the FBN support the important and necessary measures to reduce emissions and global warming. In particular, intensive research is being conducted on ways to reduce methane emissions from ruminants and the associated cooling effect, for example in the projects "eMissionCow", "MethAnLand" and "BlueCow". The consideration of ecological cycles and the use of recent biomass is crucial here.