Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2018 Sep 13;9:3734. doi: 10.1038/s41467-018-05938-3

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2018

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

Fig. 1 — Proposed climate geoengineering techniques focused on in this review, placed in the context of mitigation efforts. a Mitigation is defined here as reducing the amount of CO₂ and other climate forcers released into the atmosphere by either reducing the source activities (e.g., less energy consumption), increasing efficiency (thus reducing emissions per unit of the activity, e.g., kWh of energy produced), or removing forcers like CO₂ directly at the source prior to their emission, e.g., from the concentrated stream of CO₂ at power or industrial plants. For the latter, the captured CO₂ can either be stored subsurface (CCS—carbon capture and storage), or utilized in long-lived materials such as carbonate-based cement (CCU—carbon capture and utilization). b In contrast to mitigation (including CCS and CCU), carbon dioxide removal (CDR) aims to reduce the amount of CO₂ after it has been emitted into the ambient atmosphere, thus reducing greenhouse warming due to the absorption of terrestrial radiation (red arrows). The main proposed techniques are based on uptake of CO₂ either by photosynthesis (techniques 1–5) or by abiotic chemical reactions (techniques 6 and 7), followed by storage of the carbon in various biosphere or geosphere reservoirs. c Radiative forcing geoengineering techniques aim to modify the atmosphere-surface radiative energy budget in order to partly counteract global warming, by two distinct approaches: increasing the amount of solar shortwave radiation (yellow arrows) that is reflected back to space (techniques 8, 9, 11, and 12), or increasing the amount of terrestrial longwave radiation which escapes to space (technique 10). The focus of this class of techniques is on inducing a negative radiative forcing (i.e., cooling). Thus, in place of the commonly used misnomers solar radiation management (SRM) and albedo modification^14,15,17, which focus only on the solar radiation techniques and exclude terrestrial radiation modification by cirrus cloud thinning, we introduce the term radiative forcing based climate geoengineering, which we abbreviate to radiative forcing geoengineering (RFG)