Tuesday, August 29, 2023

Agriculture emissions rising steeply

The National Farmers Union reports that greenhouse gas emissions from agriculture have increased by 41 per cent since 1990.


While that’s highlighted in the NFU news release, in the full report prepared by Darrel Qualman, it says compared to last year’s report, nitrous oxide emissions from synthetic nitrogen fertilizer have been reduced by approximately 20 percent between 1990 and 2020 and nitrous oxide emissions from the application of organic nitrogen fertilizers (including manure) and decomposition of crop residues have been reduced by about 40 percent. 


Sequestration of carbon dioxide has increased by 100 to 400 percent, depending on the year, as Environment and Climate Change Canada changed is measuring methods.


Canada has committed to reduce economy-wide GHG emissions by at least 40 percent by 2030 and to reach net zero by 2050.


But in the news release, the NFU said total greenhouse gas  emissions from Canadian agriculture increased from 58.6 million tonnes of carbon dioxide  in 1990 to 82.6 million tonnes in 2021.


It also said emissions from nitrogen fertilizers and from fossil fuels both doubled in that same time frame.


The full report also questions the reliability of some of the data the federal government is using, such as the United Nations’ estimate of livestock methane emissions and manure management relating to nitrous oside emissions.


Qualman also notes that beef farming has reduced methane emissions in the last five years, mainly because there are fewer cattle. Dairy cattle emissions have also declined.


But the full report also said  “beef and dairy-related emissions may contribute more than 40 percent of all agricultural emissions in Canada.”

But it goes on to report “quantification of methane sources and sinks entails large uncertainties.


“There is a disconnect between the quantification of emissions tonnages from cattle and the interpretation of those reported emissions. 


“Consider this hypothetical: If the fossil fuel sector was a source only of carbon dioxide but not of methane, then current atmospheric methane concentrations would be much closer to long-term historical levels and therefore methane and cattle might not be seen as contributing to climate change. 


“That said, from many sources, humans have tripled atmospheric concentrations of methane.”


While reduced tillage gets a lot of credit for reducing emissions, Qualman said a bigger factor is the reduction in summerfallow acreage.


He also notes that the federal government is not measuring emissions related to reducing wetlands, mainly across the Prairies.


He also concludes that farmers’ carbon sequestration accounts for only a 22 per cent decrease in the balance of total emissions and that contribution is declining and likely to continue to decline.


In the conclusions in the full report, Qualman wrote that despite all the uncertainties “we have more than enough data and more than enough precision to move forward swiftly, energetically, and courageously to reduce agricultural emissions. 


“Commitments by governments to cut emissions from methane, from fertilizer, and from the economy as a whole provide clear signals that we need to act now and in each coming year to reduce emissions from all agricultural categories.”


The full 43-page report is available at  https://www.nfu.ca/publications/ag-ghg-emissions-in-cad-3rd-edition