In Norway, agricultural emissions are generally regarded to contribute about 8% of total emissions. How has this changed over time? And where do those emissions come from?
The decline has declined
The 2017 edition of Norway's National Inventory Report (NIR) on Greenhouse Gas Emissions was released earlier this month by the Norwegian Environment Agency. For agriculture there is a significant change from last year's report: While last year it was reported that emissions from Norwegian agriculture had gone down by 11% since 1990, this figure is now only 6%. What happened?
The basic answer is that the Statistics Norway and the dairy cooperative Tine did not communicate very well with each other. Tine provided the wrong numbers for how many livestock there are in Norway, and on revision there are now 24% more dairy cows in Norway (see figure, below). While industry bodies such as Tine and Nortura know exactly how many cows and pigs there are throughout the year, for national emissions calculations annual figures are needed, and that complicates matters. Many livestock are born and many die throughout the year, so there are careful definitions for what the annual number is. This is similar to measuring the number of full-time-equivalent staff a company has: you don't just add the part-timers to the full-timers. In this year's NIR, the Environmental Agency states that Statistics Norway and Tine "have assessed the data sources and data needs, and have established a cooperation to ensure that the correct data is used in the future."
Sources of agricultural emissions
So we now have a better estimate of how much agricultural emissions have dropped, but the reasons behind that drop are not so well known. What's more, the emission numbers for agriculture usually exclude activities that are clearly part of the agricultural sector: heating of glasshouses, on-farm use of diesel, cultivation of drained wetlands, and uptake of carbon by mineral soils. When these additional sources of emissions are included, the total for the agricultural sector was significantly higher, but has declined about 8.5% since 1990.
The figure below shows how different sources of emissions in the agricultural sector have changed since 1990. What's evident at a glance is that cultivation of drained wetlands ('organic soils' or 'dyrket myr') is a large and fairly stable share of the total. Normally when plants die, the dead material is rapidly decomposed by bacteria, fungi, and others, but when the dead plant material is submerged under water, only much less efficient anaerobic ("living without air") bacteria are involved. This means that carbon builds up over time in the soil, reaching very high levels. But when these wetlands are drained, and especially when they are ploughed, the carbon-rich soil becomes exposed to the air, allowing decomposition to proceed at a rapid pace. With such a lot of carbon to get through, this process goes on for many years, releasing a lot of carbon dioxide into the air.
Organic soils account for only 7% of Norway's cropland, and less than 2% of grassland, but contribute more than 2.3 million tonnes of carbon dioxide, methane and nitrous oxide emissions. Norway needs more experience in restoration of wetlands, and it is difficult to see how large areas of cultivated organic soils could be taken out of production, in strong conflict with policies to increase food production. It seems there is also a need for increased awareness. In apparent direct conflict with official statistics showing significant emissions from drained wetlands, the Industry Committee (Næringskomiteen), comprising members of parliament, recently reported to parliament that "cultivation and draining [of wetlands] are important measures for increasing food production and reducing greenhouse gas emissions" and argued that there should be "more cultivation and draining" of wetlands.
The second-largest category of emissions in this figure is the emissions of methane from the digestive systems of cattle: enteric fermentation (fordøyelsesgass). There have been considerable changes in the milk industry since 1990, and the number of mature dairy cows in Norway dropped by about a third over this period. Why? In line with declining milk consumption, production has dropped by 20%. Meanwhile, the yield of milk per cow has increased by more than 20%, largely because of more efficient feed (think soy, etc.). The combination of these two drivers means that far fewer cows are required to meet Norway's current demand for milk. But then why didn't the emissions from cattle drop by a third? Because the consumption of beef is about the same now as it was in 1990, and with a significant reduction in the number of dairy cows to meet that demand, Norway's beef cattle (ammekyr) industry has grown by almost a factor of ten. Emissions from these new cattle partly offset the reduced emissions in the dairy industry.
Apart from this change in the dairy industry, the largest drop in emissions occurs in the 'other' category (see first figure again). The main reason for this is my inclusion into this category of uptake of carbon by agricultural soils: negative emissions. The amount of CO2 absorbed by agricultural soils (both under crops and grass) since 1990 has increased significantly. But here we must be cautious. This absorption of carbon occurs almost entirely in the first year after conversion from forestry, and thereafter mineral soils are approximately in equilibrium. Effectively, the only reason for this 'improvement' in emissions in this category is because of conversion of forestry to agriculture, something that is not sustainable, and reduces the amount of carbon that forestry might otherwise absorb from the atmosphere. In addition, the update by soils was equivalent to only about 14% of the emissions from organic soils in 2015, and you can't include one in the accounts without including the other.
There are other achievements, including a reduction in carbon dioxide emissions from the glasshouse industry, about 60% down compared to 1990 because they now use cleaner fuels. Also Norwegian farmers are using significantly less lime (calcium carbonates) on their soils, resulting in a drop in emissions of more than 60% from that source.
But most categories of emissions in the agricultural sector have been stable over these 25 years. The Norwegian government has been tasking experts with how emissions in the agricultural sector could be reduced, and several solid reports have already been produced (e.g. this one). Measures include reducing food waste, shifting some consumption from red meat to white meat, ending the new cultivation of wetlands, production of biogas, biochar, improved drainage of mineral soils, and restoration of cultivated wetlands. Unfortunately, only a few of these measures have so far been costed, and this will be critical before any decision is made about how much Norwegian agriculture should contribute to Norway's overall emissions reductions targets.
On the way up again?
In the last few years total agricultural emissions have increased again. What's happened?
The category with the largest increase over the last two years was enteric methane emissions from sheep, and this is a direct result of sheep numbers having increased. The number of sheep goes up and down every few years, and this could be just another swing. It is, however, a strange time for sheep numbers to increase, when there is a growing surplus of unsold frozen sheepmeat in storage.
The next largest increase is emissions from use of artificial fertiliser. The amount of artificial fertiliser used in Norwegian agriculture has increased by more than 7% in just the last two years, leading directly to increased emissions of nitrous oxide.
Enteric methane emissions from cattle have also increased, with the steady increase of beef cattle numbers, the number of dairy cows flattening out, and some growth in the number of young cattle.
Emissions from organic soils continue their slow increase as more wetland is drained and converted to cropping or grassland.
The number of beef cattle increased again in 2016, continuing to rise to meet demand for beef, so it is likely that agricultural emissions rose again in 2016. We'll find out what SSB has to say on the 19th of May.
- Miljødirektoratet, 2017. Greenhouse Gas Emissions 1990-2015, National Inventory Report. The Norwegian Environment Agency, Oslo. Download
- Næringskomiteen, 2017. Innstilling fra næringskomiteen om Endring og utvikling - En fremtidsrettet jordbruksproduksjon, Oslo. Download
- Miljødirektoratet, Landbruksdirektoratet, 2016. Plan for restaurering av våtmark i Norge (2016-2020). Download