Carbon Dioxide Removal after Paris

Limits to Paris compatibility of CO2 capture and utilization

Geo-engineering, henceforth referred to as climate engineering, can be described as an intentional intervention on the Earth’s climate system for the purpose of temporarily reducing the increase in surface temperatures due to global warming. While it is generally acknowledged that climate engineering cannot solve the problem of global warming resulting from unrestricted greenhouse gas (GHG) emissions (Launder and Thompson, 2010), it may “buy time” for non-carbon energy systems to dominate global energy production and for GHG emissions to be reduced to safe levels. The longer meaningful global policy decisions on GHG emissions are delayed, the stronger the demand is likely to be for climate engineering research and development. As described by Anderson and Bows (2010), even if an effective global treaty on GHG emissions were to take effect now, it would still be extremely difficult to prevent mean global surface temperatures from rising above 2°C (above which it is argued that the consequences of climate change would be unacceptable). It is thus defensible to argue that some combination of GHG mitigation and climate engineering may be necessary to limit the mean increase in global surface temperatures to 2°C. A modeling study by Arora et al. (2011) also finds that a mean global warming exceeding 2°C may be unavoidable. Using updated GHG emission scenarios and an upgraded Earth system model (which accounts for aerosol effects and represents the carbon-cycle more realistically), the study finds that even under the lowest, most optimistic GHG emission scenario, the global average temperature will still increase more than 2°C (the limit agreed to by various governments in the Copenhagen accord) by 2100. To limit warming to 2°C by 2100, carbon dioxide emissions would need to be reduced to zero over the next 50 years followed by ongoing carbon sequestration (removal of CO2 from the atmosphere) through the end of this century. While few scientists advocate tinkering with the earth’s climate (Schneider 2010), climate engineering of some kind may become a necessity rather than an option. Two types of climate engineering have been recognized: carbon dioxide removal (CDR) strategies and solar radiation management (SRM). CDR approaches can be biological, such as iron fertilization of the oceans to increase phytoplankton uptake of CO2 (Lampitt et al., 2010; Smetacek and Naqvi, 2010), or they can be physically based, such as the direct capture

We introduce solar geoengineering (SG) and carbon dioxide removal (CDR) into an integrated assessment model to analyze the trade-offs between mitigation, SG, and CDR. We propose a novel empirical parameterization of SG that disentangles its efficacy, calibrated with climate model results, from its direct impacts. We use a simple parameterization of CDR that decouples it from the scale of baseline emissions. We find that (a) SG optimally delays mitigation and lowers the use of CDR, which is distinct from moral hazard; (b) SG is deployed prior to CDR while CDR drives the phasing out of SG in the far future; (c) SG deployment in the short term is relatively independent of discounting and of the long-term trade-off between SG and CDR over time; (d) small amounts of SG sharply reduce the cost of meeting a [Formula: see text]C target and the costs of climate change, even with a conservative calibration for the efficacy of SG.

Carbon dioxide is essential to life on Earth, however its concentration in the atmosphere has significantly
\nincreased since pre-industrial era, causing global warming and climate change. To reduce these effects, the
\nParis Climate Agreement has established greenhouse gas emissions reduction targets, which can be
\nachieved by decarbonizing energy-intensive industries as electricity production. Post-combustion removal of
\ncarbon dioxide can be obtained by employing aqueous solutions of amines - in most of the cases
\nMonoEthanolAmine (MEA) is used - which absorb this acid gas from the flue gas streams and are then
\nregenerated and recycled. They are widely employed, though being characterized by several drawbacks, as
\nthe high energy requirement at the reboiler of the regeneration section. Therefore, though adding Carbon
\nCapture & Storage (CCS) to a power plant makes the production of electricity more advantageous from an
\nenvironmental point of view, its operation represents an economic loss for the plant. Possible ways of
\nminimizing the economic disadvantages due to the carbon dioxide removal section include running this section
\nin flexible mode, on the basis of the price of electricity which varies from hour to hour and from day to day. The
\nCapture Level Reduction (CLR) and the Solvent Storage (SS) methods are two possible solutions for flexible
\noperation. This work focuses on the purification of a flue gas stream from a power plant fed with natural gas
\nand performs simulations and techno-economic analyses of the CLR and SS modes, taking into account also
\nthe possible application of a carbon tax. By analysing the obtained results a comparison between the two
\noptions is carried out, and the best operating mode is determined.

Challenges and Opportunities for Integrated Modeling of Climate Engineering

Cutting through the noise on negative emissions

Carbon removals from nature restoration are no substitute for steep emission reductions

The Paris Agreement has set stringent temperature targets to limit global warming to 2°C above preindustrial level, with efforts to stay well below 2°C. At the same time, its bottom-up approach with voluntary national contributions makes the implementation of these ambitious targets particularly challenging. Climate engineering – both through carbon dioxide removal (CDR) and solar radiation management (SRM) – is currently discussed to potentially complement mitigation and adaptation. Results from integrated assessment models already suggest a significant role for some forms of climate engineering in achieving stringent climate objectives1. However, these estimates and their underlying assumptions are uncertain and currently heavily debated2–4. By reviewing the existing literature and reporting the views of experts, we identify research gaps and priorities for improving the integrated assessment of climate engineering. Results point to differentiated roles of CDR and SRM as complementary strategies to the traditional ones, as well as diverse challenges for an adequate representation in integrated assessment models. We identify potential synergies for model development which can help better represent mitigation and adaptation challenges, as well as climate engineering.

This article adds conceptual discipline to a well‐rehearsed but largely intuitive argument within the climate engineering community that carbon dioxide removal (CDR) and solar radiation management (SRM) should be treated separately – ‘split’ rather than ‘lumped’ – in policy discussions. Specifically, we build the first, theoretically derived argument for ‘splitting’. We do this by engaging a set of theoretical insights from the international relations literature, having to do with the relationship between problem structure and institutional design. Centrally, we apply some key elements of problem structure – which allows us to compare policy issues along variables such as geographic scope, costs, and actor number and asymmetries – to the cases of SRM and CDR. By analyzing their problem structures, we demonstrate that SRM and CDR are different in ways that are likely to yield different state preferences for institutional design, and thus policy proposals that split SRM and CDR are more likely to be adopted by states. In short, we construct a theoretical argument for ‘splitting’ SRM and CDR governance in global policy discussions.

Chapter 10 - Climate engineering

Governance of bioenergy with carbon capture and storage (BECCS): accounting, rewarding, and the Paris agreement

International CO2 emissions reduction commitments are insufficient to avert damaging global warming and imperil a sustainable future. Climate engineering approaches are increasingly proposed as near-term intervention strategies, but deployment of these controversial techniques will require careful engagement with and the support of the public. New quantitative measurements of public perceptions for six climate engineering approaches show that the public of the United Kingdom (UK), United States (US), Australia (AU) and New Zealand (NZ) continue to have little knowledge of climate engineering. All approaches are regarded unfavourably, albeit less so for carbon dioxide removal (CDR) than solar radiation management (SRM). Knowledge and perceptions are remarkably similar between countries although UK and US respondents are more favourable towards SRM and UK respondents are more favourable towards CDR. Stratospheric aerosol injection is the most negatively perceived approach. Support for small-scale trials is also higher for CDR approaches than SRM. Statistical analyses yield mixed relationships between perceptions of climate engineering and age, political affiliation and pro-ecological views. Thus far, attempts to engage the public with climate engineering have seen little change over time and consequently, there is growing urgency to facilitate careful citizen deliberation using objective and instructive information about climate engineering.

Legal guardrails on states’ dependence on carbon dioxide removal to meet climate targets

Net-zero emissions chemical industry in a world of limited resources

Climate change is a complex and contentious public issue, but the risk-management options available to us are straightforward and have well-characterized strengths and weaknesses.