Farming overtakes deforestation and land use as a driver of climate change
A new study finds that greenhouse gas emissions from growing crops and raising livestock are now higher than from deforestation and land use change.
The research, published in Global Change Biology, estimates the contribution of agriculture, deforestation and land use change to global emissions. While the emissions of the sector as a whole are dropping, emissions from agriculture are still on the rise, the research says.
The study combines three global datasets of greenhouse gas emissions for the ‘Agriculture, Forestry and Other Land Uses’ (AFOLU) sector. It includes emissions from different sectors and human activities such as deforestation, clearing and burning biomass, and from raising and feeding livestock.
Whether the actual emissions are of carbon dioxide, methane or nitrous oxide, the figures are all converted into figures of ‘carbon dioxide equivalent’, which makes them easier to compare.It shows a trend where the emissions of the AFOLU sector as a whole are falling, while emissions from agriculture are still on the rise.
As a whole, the sector takes up a decreasing share of total manmade emissions, the study finds. In the 1990s, AFOLU was responsible for around 29 per cent of our emissions, but this dropped to 24 per cent in the 2000s and then to 21 per cent in 2010.
There are two reasons for this: first, emissions from deforestation and land use change have fallen over the past two decades, and second, the overall total of manmade greenhouse gas emissions are growing.
The result is that AFOLU is responsible for a decreasing share of a growing global emissions pie. You can see this is the infographic below, which shows the figures for one of the three datasets that the study uses.
Within the AFOLU sector, the study shows that while emissions from deforestation and land use change are dropping, emissions from agriculture are on the increase.
On average, cutting down trees and clearing land contributed the equivalent of 6.4 gigatonnes (Gt) of carbon dioxide to the atmosphere each year of the 1990s. This fell to 5.4 Gt in the 2000s and to 4.9 Gt in 2010, the study finds.
In comparison, global emissions from crop and livestock production rose from 4.8 Gt in the 1990s, to 5.2 Gt in the 2000s and to 5.4 Gt in 2010. Emissions from agriculture are growing at around one per cent per year, the study estimates.
The news follows a recent global survey by Chatham House which identified a lack of awareness about the size of greenhouse gas emissions from meat and dairy production.
Less than a third of people surveyed thought that it makes a large contribution to climate change, despite meat and dairy having a carbon footprint larger than all the cars, trains, planes and ships in the world, Chatham House says.
With the likes of the Intergovernmental Panel on Climate Change including agriculture as part of the wider AFOLU group, the new study shows why it’s necessary to look into the detail of how and where emissions are changing.
Article reference: Francesco N. Tubiello1, Mirella Salvatore, Alessandro F. Ferrara, Simone Rossi, Riccardo Biancalani, Rocio D. Condor Golec, Sandro Federici, Heather Jacobs, Alessandro Flammini, Paolo Prosperi, Paola Cardenas, Josef Schmidhuber, Maria J. Sanz Sanchez, Pete Smith, Jo House, Nalin Srivastava, ‘The Contribution of Agriculture, Forestry and other Land Use activities to Global Warming, 1990-2012: Not as high as in the past’, Global Change Biology, DOI: 10.1111/gcb.12865