Non-Sewered Sanitation Systems’ Global Greenhouse Gas Emissions: Balancing Sustainable Development Goal Tradeoffs to End Open Defecation

Abstract

Discharge of excreta into the environment and the use of decentralized sanitation technologies, such as septic tanks, pit latrines and ecological sanitation variants (i.e., container-based sanitation), contribute to greenhouse gas (GHG) emissions but have remained poorly quantified. The purpose of this analysis was to investigate the impacts that meeting Sustainable Development Goal (SDG) 6.2 (i.e., ending open defecation by 2030) would have on SDG 13 (i.e., combatting climate impacts). The current Intergovernmental Panel on Climate Change GHG estimation methodology was used as the basis for calculations in this analysis, augmented with improved emission factors from collected data sets for all types of on-site sanitation infrastructure. Specifically, this assessment focused on the three different service levels of sanitation (i.e., improved, unimproved and no service) as defined by UNICEF and WHO as they pertain to three Shared Socioeconomic Pathways. This analysis considered the 100-year global warming potential values in carbon dioxide equivalents of methane and nitrous oxide that can be emitted for each scenario and decentralized sanitation technology. Ultimately, six scenarios were developed for various combinations of pathways and sanitation technologies. There was significant variability between the scenarios, with results ranging from 68 Tg CO2eq/year to 7 TgCO2eq/year. The main contributors of GHG emissions in each scenario were demonstrated to be septic tank systems and pit latrines, although in scenarios that utilized improved emission factors (EFs) these emissions were significantly reduced compared with those using only standard IPCC EFs. This analysis demonstrated that using improved EFs reduced estimated GHG emissions within each SSP scenario by 53% on average. The results indicate that achieving SDG sanitation targets will ultimately increase GHG emissions from the current state but with a relatively small impact on total anthropogenic emissions. There is a need for the continued improvement and collection of field-based emission estimations to refine coarse scale emissions models as well as a better characterization of relevant biodegradation mechanisms in popular forms of on-site sanitation systems. An increase in the understanding of sanitation and climate change linkages among stakeholders will ultimately lead to a better inclusion of sanitation, and other basic human rights, in climate action goals.

Non-negligible greenhouse gas emissions from non-sewered sanitation systems: A meta-analysis

“… Shaw et al (2021) also estimated the GHG emissions of NSSS as 560 Mt CO 2 e/year, which is slightly higher than our results. Shaw et al (2021) reported their results as 20 Mt CO 2 e/year, but these data seemed to have a unit problem not multiplied by the GWP value of CH 4 relative to CO 2 . We have corrected this problem.…”

“…Every person in the world who abandons OD and uses NSSS would add about 111 kg CO 2 e/year, which means an increase of 55 Mt CO 2 e/year when OD is completely eliminated. Evidence such as these has important implications for the development of sanitation systems, which, as Shaw et al (2021) argued, will provide a clear path to the sustainable development of NSSS.…”

Container-based sanitation in urban Haiti: how can it improve human rights as a component of citywide inclusive sanitation?

“…With expansion, per-capita service delivery costs are likely to decrease, creating a positive feedback loop (EY 2020). Furthermore, public service providers investing in broad-scale CBS application may be able to avail themselves of atypical funding resources, such as carbon mitigation credits (Shaw et al 2021) or other environmentally linked financial incentives, due to the unique characteristics of CBS technologies. Alternatively, with growing recognition of the ability for CBS to meet SDG 6.2 and human rights or alleviate some environmental pollution crises, emerging regulations or international agreements could create positive pressure to adopt CBS.…”

Investigation on the Status Quo of Ecological Environment Construction in Northeast China from the Perspective of Dual Carbon Goals

“…In particular, it has caused an important impact on the drought situation in the northeast and central and western regions. Scientific research has confirmed that the reduction of rainfall is the main manifestation of drought in the central and western regions of Northeast China, resulting in the decline of the natural environment [ 17 ].…”