Modeling meets science and technology: an introduction to a special issue on negative emissions

Abstract

This article introduces the Climatic Change special issue dedicated to negative emissions technologies, also known as carbon dioxide removal (CDR) from the atmosphere. CDR is the only class of mitigation options able to reduce the carbon stock in the atmosphere significantly. In this special issue CDR is explored from the perspectives of integrated assessment, technology optimization, environmental science, and political science.

Differences between carbon budget estimates unravelled

“…Earlier studies have indeed shown that this is the case 7,8,18,19 , at least for peak warming and monotonously increasing cumulative carbon emissions. If a set carbon budget limit is exceeded, CO 2 needs to be removed actively from the atmosphere afterwards [20][21][22] to bring emissions back to within the budget. Figure 1 illustrates this path independency (even for moderate amounts of net negative CO 2 emissions), and shows with the simple carbon-cycle and climate model MAGICC 7,23,24 that even with large variations in the pathway of CO 2 emissions during the 21 st century, the transient temperature paths as a function of cumulative CO 2 emissions are very similar -a characteristic also found in other models 18,25 .…”

Betting on negative emissions

“…Along with afforestation, the production of sustainable bioenergy with carbon capture and storage (BECCS) is explicitly being put forth as an important mitigation option by the majority of integrated assessment model (IAM) scenarios aimed at keeping warming below 2 °C in the IPCC's fifth assessment report (AR5) 6 . Indeed, in these scenarios, IAMs often foresee absorption of CO 2 via BECCS up to (and in some cases exceeding) 1,000 Gt CO 2 over the course of the century 7 , effectively doubling the available carbon quota.…”

The Potential of Photoelectrochemical Carbon Sinks

“…The currently explored options are direct air capture and biomass production. [6][7][8][9][10][11] Renewably driven direct air capture is believed to be expensive and has not yet demonstrated scalability. Therefore, the currently most feasible option appears to be the use of natural photosynthesis to generate biomass through afforestation or ocean fertilization.…”