Alternative pathways to the 1.5 °C target reduce the need for negative emission technologies

Abstract

Mitigation scenarios that achieve the ambitious targets included in the Paris Agreement typically rely on greenhouse gas emission reductions combined with net carbon dioxide removal (CDR) from the atmosphere, mostly accomplished through large-scale application of bioenergy with carbon capture and storage, and afforestation. However, CDR strategies face several difficulties such as reliance on underground CO 2 storage and competition for land with food production and biodiversity protection. The question arises whether alternative deep mitigation pathways exist. Here, using an integrated assessment model, we explore the impact of alternative pathways that include lifestyle change, additional reduction of non-CO 2 greenhouse gases and more rapid electrification of energy demand based on renewable energy. Although these alternatives also face specific difficulties, they are found to significantly reduce the need for CDR, but not fully eliminate it. The alternatives offer a means to diversify transition pathways to meet the Paris Agreement targets, while simultaneously benefiting other sustainability goals.

The contradiction of the sustainable development goals: Growth versus ecology on a finite planet

“…Both the Van Vuuren et al () and Grubler et al () scenarios cited above represent a degrowth approach, showing the Paris target can be brought within reach (and, in the case of Grubler, achieved) by reducing material throughput and energy demand, with positive synergies for the social and environmental objectives of the SDGs. The Grubler et al scenario was included in the IPCC Special Report on 1.5°C () as an alternative to relying on speculative negative emissions technologies.…”

“…These models are restricted to relatively conventional approaches, such as taxes and efficiency improvements. Alternative approaches—including a planned transition to wind and solar power, reductions in global population and meat consumption, and so forth (i.e., IRENA, ; Van Vuuren et al, )—may allow for some continued global economic growth, but significantly lower than the rate required by Goal 8. Schroder and Storm () find that, if we are to reduce emissions in line with the 2°C target, global economic growth can be no more than 0.45% per year over the coming decades.…”

“…Third, the necessary CO2 storage capacity may not exist (De Coninck & Benson, ; Global CCS Institute, ). Anderson and Peters () conclude that “BECCS thus remains a highly speculative technology” and that relying on it is therefore “an unjust and high stakes gamble”; if it is unsuccessful, “society will be locked into a high‐temperature pathway.” This conclusion is shared by a growing number of scientists (e.g., Fuss et al, ; Vaughan & Gough, ; Larkin, Kuriakose, Sharmina, & Anderson, ; Van Vuuren et al, ), and by the European Academies Science Advisory Council ().…”

“…The International Renewable Energy Association (IRENA, ) modelled a rapid shift to solar and wind energy with installation rates up to 4.6 times faster than the present, plus improvements in energy intensity of the global economy at double the historical rate. Van Vuuren et al () modelled a decline of global population to 6.9 billion by 2100; 80% reduction of meat consumption by 2050; and a rapid shift to the most efficient cars, airplanes, and production facilities for cement and steel, in addition to a carbon tax and other aggressive mitigation strategies. Both studies found that even with these highly optimistic assumptions in place, the pressures of continued GDP growth drive emissions to exceed the carbon budgets for 1.5°C and 2°C.…”

Afforestation for climate change mitigation: Potentials, risks and trade‐offs

“…Ambitious climate change mitigation scenarios aiming to limit global warming to 2°C or less require very rapid reductions in greenhouse gas (GHG) emissions (Clarke et al, ; van Vuuren et al, ). Even if stringent policies are adopted, it is likely that negative CO 2 emissions will become indispensable to achieve the Paris Agreement climate goal as shown in many mitigation scenario studies (Rogelj et al, ; Van Vuuren, Hof, Sluisveld, & Riahi, ; van Vuuren et al, ). The need for such negative emissions highlights the role of land use in the context of mitigation.…”