The researchers found that well-established agricultural management practices such as planting cover crops, optimizing grazing and sowing legumes on rangelands, if instituted globally, could capture enough carbon from the atmosphere and store it in the soil to make a significant contribution to international global warming targets.
Their initial aim was to determine if such practices could reduce global temperatures at least 0.1 degree Celsius (0.18 degrees Fahrenheit). This is one-tenth of the Intergovernmental Panel on Climate Change’s goal of limiting the average global temperature increase between now and the year 2100 to 1 degree Celsius (1.8ºF), or 2 above temperatures before the industrial revolution.
When combined with aggressive carbon emission reductions – the best scenario for limiting warming from climate change – the study found that improved agricultural management could reduce global temperatures 0.26 degrees Celsius – nearly half a degree Fahrenheit – by 2100.
“As someone who has been working on carbon sequestration for a long time, I have always had this question in the back of my mind, ‘Will sequestration in soils make a difference with climate change at a global scale?’ ” said study senior author Whendee Silver, a professor of environmental science, policy and management at UC Berkeley. “We found that there are a wide range of practices deployable on a large scale that could have a detectable worldwide impact. A big take-home message is that we know how to do this, it is achievable.”
By throwing in biochar, a controversial soil additive – essentially charcoal – obtained by burning crop residue in an oxygen-free environment, these practices could offset even more warming, potentially as much as 0.46 degrees Celsius (0.7ºF).
The caveat, Silver said, is that this “is only achievable if you couple sequestration with aggressive emissions reduction.” If carbon concentrations increase in the atmosphere, then sequestration becomes less effective at reducing temperature. We would have to pull much more carbon out to realize the same reductions.
She and her colleagues, including lead author Allegra Mayer, a UC Berkeley graduate student, will publish their findings Aug. 29 in the online journal Science Advances.
See more at http://news.berkeley.edu/2018/08/29/improving-soil-quality-can-slow-global-warming/