(Mis)conceptions about modeling of negative emissions technologies

Abstract

Intentionally removing carbon from the atmosphere with negative emission technologies (NETs) will be important to achieve net-zero emissions by mid-century and to limit global warming to 2°C or even 1.5°C (IPCC 2018). Model scenarios that consider NETs as part of mitigation pathways are still largely restricted to afforestation and bioenergy with carbon capture and storage (BECCS), while the '[f]easibility and sustainability of [NETs] use could be enhanced by a portfolio of options deployed at substantial, but lesser scales, rather than a single option at very large scale' (IPCC 2018, p 19). Here, we show the results from an anonymous expert survey, including 32 Earth-System-Model (ESM) experts and 18 Integrated-Assessment-Model (IAM) experts, about the role of NETs in future climate policies and about how well the various technologies are represented in current models. We find that they strongly support the view that technology portfolios are required to achieve negative emissions, however, the responses show that the number and range of NETs that can be assessed in IAMs is small and that IAMs and ESMs are rather applied to analyze technologies separately than in combination. IAM experts in particular consider BECCS as part of a future NETs portfolio; but at the same time, all experts judge the constraints BECCS would face regarding future overall feasibility and more particularly regarding resource competition to be the highest. Regarding the assessment of constraints the ESM experts are much more skeptical than the IAM experts; they also think that the BECCS carbon removal pathways are less sufficiently represented in ESMs compared to what the IAM experts thinks about the representation in their models. Despite the perceived need for NETs portfolios, the range of NETs which can be assessed in IAMs is rather small and ocean NETs have, so far, mostly been overlooked by the IAM experts.

Attitudes on Carbon Capture and Storage (CCS) as a Mitigation Technology within the UNFCCC

“…As yet, however, BECCS, alongside afforestation, remains a key technology in assessments of the potential for CO2 removals. This is likely to remain the case in the near future (see for example [43]).…”

“…The debate on the role that BECCS should play in producing negative emissions is relatively nascent but is becoming more and more vivid by the day, as is the research on negative emissions [39]. The potential of BECCS to produce negative emissions on large scales has meant that it has received a lot of attention in climate modelling, and increasingly also in politics [40,41], but it is also noted that modeling the global potential of a large set of highly context-dependent negative emission technologies is difficult [42,43]. In the near future, we will likely see an intensified debate also on other CO2 removal options, and how these may supplement BECCS deployment.…”

Public Perceptions of Ocean-Based Carbon Dioxide Removal: The Nature-Engineering Divide?

“…In an expert survey, earth system modelers and integrated assessment modelers perceived political and public acceptability on average as the strongest constraint on the feasibility of ocean iron fertilization, alkalinity enhancement, and artificial upwelling followed by cost effectiveness. In contrast, they only saw it as a weak constraint on blue carbon management (Rickels et al, 2019). This assessment of the role of public acceptability might partly be fueled by past protests against research projects such as LOHAFEX on ocean iron fertilization in the Southern Ocean (Schiermeier, 2009a,b) and SPICE on stratospheric aerosol injection in the UK (Pidgeon et al, 2013), proposals for CO 2 -injection off the coast of Hawaii and Norway (Gewin, 2002;Giles, 2002;Figueiredo et al, 2003;Scott, 2006) or the ocean fertilization project by the Haida Salmon Restoration Corporation in international waters off the Canadian west coast (Tollefson, 2017;Gannon and Hulme, 2018).…”

“…Public acceptability ranks highly on the list of potential constraints on CDR deployment (Fuss et al, 2014;IPCC, 2018;GESAMP, 2019;Rickels et al, 2019). In an expert survey, earth system modelers and integrated assessment modelers perceived political and public acceptability on average as the strongest constraint on the feasibility of ocean iron fertilization, alkalinity enhancement, and artificial upwelling followed by cost effectiveness.…”

Unveiling assumptions through interdisciplinary scrutiny: Observations from the German Priority Program on Climate Engineering (SPP 1689)

“…In CDRMIP, the value of interdisciplinary dialogues is recognized to such a degree that they will inform the design of all new experiments. The interdisciplinary dialogue also spurred further research efforts to identify modeling biases and misconceptions (Rickels et al 2019).…”