Designing effective mitigation policies for greenhouse gas (GHG) emissions from agriculture requires understanding the mechanisms by which management practices affect emissions in different agroclimatic conditions. Agricultural GHG emissions and carbon sequestration potentials have been extensively studied in the Mediterranean biome, which is a biodiversity hot spot that is highly vulnerable to environmental changes. However, the absolute magnitude of GHG emissions and the extent to which research efforts match these emissions in each production system, are unknown. Here, we estimated GHG emissions and potential carbon sinks associated with crop and livestock production systems in the Mediterranean biome, covering 31 countries and assessing approximately 10,000 emission items. The results were then combined with a bibliometric assessment of 797 research publications to compare emissions estimates obtained with research efforts for each of the studied items. Although the magnitude of GHG emissions from crop production and the associated carbon sequestration potential (261 Tg CO2eq yr−1) were nearly half of those from livestock production (367 Tg CO2eq yr−1), mitigation research efforts were largely focused on the former. As a result, the relative research intensity, which relates the number of publications to the magnitude of emissions, is nearly one order of magnitude higher for crop production than for livestock production (2.6 and 0.4 papers Tg CO2eq−1, respectively). Moreover, this mismatch is even higher when crop and livestock types are studied separately, which indicates major research gaps associated with grassland and many strategic crop types, such as fruit tree orchards, fiber crops, roots and tubers. Most life cycle assessment studies do not consider carbon sequestration, although this single process has the highest magnitude in terms of annual CO2eq. In addition, these studies employ Tier 1 IPCC factors, which are not suited for use in Mediterranean environments. Our analytical results show that a strategic plan is required to extend on-site field GHG measurements to the Mediterranean biome. Such a plan needs to be cocreated among stakeholders and should be based on refocusing research efforts to GHG balance components that have been afforded less attention. In addition, the outcomes of Mediterranean field studies should be integrated into life cycle assessment-based carbon footprint analyses in order to avoid misleading conclusions.
Bibliographical noteFunding Information:
The authors are grateful to the Spanish Ministry of Economy and Competitiveness (AgroSceNA-UP, PID2019-107972RB-I00) and Asociación Valor Ecológico – Ecovalia. EA is supported by a Juan de la Cierva research contract from the Spanish Ministry of Economy and Competitiveness (IJC2019-040699-I and FJCI-2017-34077). ASC would like to thank the Autonomous Community of Madrid and UPM for their economic support through the research project APOYO-JOVENES-NFW8ZQ-42-XE8B5K. EA and ASC acknowledge the Spanish National Institute for Agricultural and Food Research and Technology and the Agencia Estatal de Investigación Grant (MACSUR02-APCIN2016-0005-00-00). The authors would like to thank Dr. Luis Lassaletta for his helpful comments with respect to the manuscript. The authors gratefully acknowledge the editor and two anonymous reviewers for their constructive and useful suggestions.
- Agricultural GHG emissions
- Carbon sequestration
- Livestock GHG emissions
- Mediterranean agriculture
- Research gaps