Amid the frequent bad news about climate change, some potentially good news has emerged: Existing technologies, diligently applied, could enable the world to meet the target set for reducing agricultural methane emissions by 2030.
That’s the conclusion of a new international study that has its roots in Penn State’s College of Agricultural Sciences. The work was initiated by Alexander Hristov, distinguished professor of dairy nutrition, in 2015 when he was the chair of the Feed and Nutrition Network of the 35-country Global Research Alliance on Agricultural Greenhouse Gases.
In the meta-analysis published today (May 10) in the Proceedings of the National Academy of Sciences (PNAS), a group of experts in livestock emissions from around the world reviewed hundreds of peer-reviewed studies for strategies designed to decrease enteric methane emissions while maintaining or increasing animal productivity. That latter aspect — not reducing the quality and quantity of animal production — is critical for the adoption of these practices by livestock producers, says Hristov, who is a co-author of the paper.
The researchers found that the world could meet the targets for 2030 set by the 2015 Paris climate agreement — with the proviso that the strategies detailed in the accord be fully adopted, a goal that would require concerted action to identify and remove adoption barriers and implement the strategies. Under the 2015 Paris agreement, methane from agriculture must be reduced by 11 to 30% by 2030, if the world is to limit global warming to 2.7 degrees Fahrenheit.
“This study shows that meeting the Paris targets is mostly within our grasp — certainly in the developed world — provided we can summon the political will to do so,” said lead researcher Claudia Arndt, senior scientist and co-leader of the Mazingira Centre, a laboratory equipped to measure agricultural greenhouse gas emissions, which is operated by the International Livestock Research Institute in Kenya.
The research shows effective strategies to reduce enteric methane emissions and meet agricultural climate targets, Arndt added. Because a 100% adoption of these strategies is unlikely, other proposed means of decreasing methane production, such as strategies that remove emissions from the supply-and-demand side of the agricultural sector, are needed.
Methane is a byproduct of microbes in the digestive tract of ruminants decomposing feed, a process called enteric fermentation. The world’s billion or so ruminants — cattle, sheep and goats mostly — then belch out the methane, contributing 5% of the total anthropogenic greenhouse gas emissions.
Ruminants provide about half the animal protein produced by livestock. In low- and middle-income countries, where consumption of animal-source foods often is below recommended dietary levels, ruminant livestock play a critical role in food security and provide a host of other benefits, such as traction and manure for fuel and fertilizer. In contrast, in high-income countries, the consumption of animal protein often is above recommended levels.
Because of ruminants’ multiple uses and their contribution to the United Nations’ Sustainable Development Goals, the researchers focused on strategies that reduce methane emission but simultaneously increase animal production per unit of input. The study identified three practices related to feed management that could reduce methane emission per unit of meat or milk by an average of 12% and five practices related to reducing daily methane emissions by 21% on average.
The strategies included reducing ruminants' grazing on mature grass and increasing feeding level. The analysis also considered strategies such as supplementation with methane inhibitors and so-called electron sinks as well as feeding oils and tanniferous (containing tannin) forages to reduce daily methane emissions while maintaining animal production.
The scientists calculated global reductions using Europe to represent high-income countries and Africa to represent low- and middle-income countries, Hristov pointed out.
In Europe, they found multiple scenarios that did not require 100% adoption of identified strategies but that still could meet the 2030 targets. However, the researchers reported, meeting the more stringent 2050 targets set by the Paris climate agreement would require wholesale adoption by livestock producers. In Africa, by contrast — because of that continent's growing human and livestock population — even the most concerted efforts that would significantly reduce methane production per animal would not be enough to fully meet 2030 or 2050 targets.
This international study originated from the Global Network project coordinated by Hristov, who has been conducting research related to measuring and mitigating enteric methane emissions for more than 20 years. The work is funded by the U.S. Department of Agriculture through the European Joint Programming Initiative on Agriculture, Food Security and Climate Change.
The project focus was to collate large international databases on environmental emissions from ruminants and develop robust models to more accurately predict enteric methane and nitrogen emissions. The study also evaluated the efficacy of mitigation practices for dairy and beef cattle and small ruminants.
The Global Network project team has produced several reports in high-impact scientific journals, Hristov noted, with the current PNAS article being one of them. The database used in the analysis is freely available through Penn State’s data commons, he said, and the research team intends to make it a live, global database that will be updated continuously.Source : psu.edu