Researchers at Australia's Queensland University of Technology (QUT) have found a much more accurate means of measuring agricultural emissions of nitrous oxide (N2O), a potent greenhouse gas (GHG) that's a significant contributor to total GHG emissions. Based on "groundbreaking data" on N2O emissions from a QUT colleague, QUT Institute for Future Environments Smart Futures Fellow Professor Richard Conant's new statistical approach improves global N2O emissions estimates by as much as 65%, according to a PhysOrg article.
It's estimated that agriculture is responsible for some 20% of global GHG emissions, primarily due to methane emissions associated with livestock. Though less than carbon dioxide (CO2) emissions, N20 emissions are a big part of that, primarily the result of N2O emissions from fertilizers.
Three-quarters of estimated global agricultural N20 emissions came from fertilizer, according to Conant, who shared the 2007 Nobel Peace Prize with Al Gore as a member of the UN Intergovernmental Panel on Climate Change (IPCC).
"We're providing a tool that has significantly improved the accuracy of measuring N2O," Conant was quotes as saying. "Our hope is that this information will enable developing countries that lack detailed measurements to keep better track of N2O emissions."
Prof. Conant's new statistical method and estimates are based on a new N2O emissions data set compiled by fellow QUT Professor Peter Grace. Conant's statistical approach then analyzes the proportion of fertilizer lost as N2O.
Accounting for 50% of global N2O emissions, Conant, Grace and PhD. student Aaron Beranier found that N2O emissions are greatest in the US, Europe, East Asia and Japan. Africa and the former USSR accounted for another 13%.
Efficient Fertilizer Use
Though the quantity of fertilizer used in agriculture is important, efficient use of nitrogen in fertilizer is even more important, according to Conant. Nitrogen and fertilizer use is more efficient in the US, Europe and Japan as compared to that in Africa and the former USSR, he noted, producing more food per unit.
Conant said the new statistical method can help developing countries become more efficient in producing food and enhance food security at a time when population growth, climate change and resource scarcity are placing increasing strains on both. "This latter group of countries is not using very much nitrogen on their crops, which is affecting their ability to produce food," he said.
Developed and developing countries need to take account of externalities, such as nitrogen pollution and GHGs even as they strive to increase agricultural output, he cautioned. Simply increasing fertilizer use to meet growing food demand could accelerate N2O emissions faster than previously estimated, he warned.
A 2004 IPCC report estimated that 36 gigatons of CO2 was emitted into the atmosphere every year as compared to 3 gigatons of N2O and 4.5 gigatons of methane, the latter two being more potent than CO2.
Prof. Conant's research paper, Regionally-differentiated estimates of cropland N2O emissions reduce uncertainty in global calculations, has been published in Global Change Biology.