Climate change risk management approaches (i.e., policy options) generally fall into four broad categories: 1) mitigation—efforts to reduce greenhouse gas emissions; 2) adaptation—increasing society’s capacity to cope with changes in climate; 3) geoengineering or climate engineering—additional, deliberate manipulation of the earth system that is intended to counteract at least some of the impacts of greenhouse gas emissions; and 4) knowledgebase expansion—efforts to learn and understand more about the climate system, which can help support proactive risk management.
Each category of response consists of a broad family of potential options (described in greater detail below), most of which have well-known strengths and weaknesses. In some cases the boundaries between the categories becomes somewhat fuzzy (e.g., efforts to reduce emissions might increase adaptive capacity in some cases and vice versa). Indeed, many experts characterize geoengineering approaches as mitigation or adaptation rather than a separate category of risk management.
None of the risk management options is mutually exclusive. Indeed, comprehensive climate change risk management almost certainly includes a combination of policy responses. However, policy choices necessarily integrate both objective information about the climate system and our relationship with it, and subjective value judgments such as whether we are more averse to the risks of changes in climate or the policy responses, the ways we assess issues of fairness among nations and peoples, and the consideration we give to cultural heritage or nonhuman species. This creates a complex and often contentious risk management challenge.
Higgins, 2014; Edenhofer et al. 2014; Field et al. 2014
By reducing emissions, mitigation reduces society’s future contributions to greenhouse gas concentrations in the atmosphere. Ultimately, this can help reduce the amount that climate will change and thereby increase the potential that societal impacts will remain manageable.
Adaptation involves planning for climate impacts, building resilience to those impacts, and improving society’s capacity to respond and recover. This can help reduce damages and disruptions associated with climate change.
Geoengineering refers to deliberate, often global-scale, manipulations of the climate system. Two categories of geoengineering are most prevalent within scientific and policy discussions: solar radiation management (offsetting human-caused warming due to greenhouse gas emissions by reflecting incoming sunlight back to space) and carbon removal and sequestration (extracting carbon dioxide from the air and storing it deep in the ground or ocean).
Policies can also be designed to expand the knowledge base relating to the climate system or to reveal information relating to the management of risks associated with climate change.