Key Concepts & Definitions

The following are some key concepts and associated definitions and infographics. See resources and publications to find more information related to these.

Solar Geoengineering

Solar Geoengineering (also referred to as solar radiation modification or SRM) is the large-scale and intentional intervention to increase the amount of sunlight reflected back into space to counteract some types of climate change impacts.

Large Scale: Many small actions affect how much sunlight is reflected but solar geoengineering is focused on interventions that are resource-intensive and have big, risky effects.

Intentional: There are both natural and accidental ways of changing how much sunlight is reflected, but the deliberate manipulation of Earth’s reflectivity is novel and unprecedented.  

Sunlight Reflection: Greenhouse gases increase the proportion of the sun’s energy that remain in the atmosphere as heat. To reduce this effect, we must reduce greenhouse gas emissions, but solar geoengineering could also reduce the amount of sunlight that is absorbed by the Earth at atmosphere by reflecting it back into space as a complimentary approach to address a subset of climate impacts. 

Solar geoengineering has the potential to protect the most vulnerable from some types of major climate impacts, but does not address all climate impacts (e.g. it cannot address ocean acidification), and also presents a range of ecological and social risks and challenges.


There are a variety of ways that sunlight might be reflected back into space, but there are two techniques that have received the most attention:

Stratospheric Aerosol injection (SAI)

SAI would involve the insertion of small particles into the upper atmosphere. This would reflect a very small proportion of sunlight back into space.

Marine cloud brightening (MCB)

MCB would use the spraying of sea salt to create and brighten clouds. More clouds and brighter clouds would make the planet more reflective.


In short, solar geoengineering governance refers to actions that steer or influence how decisions about solar geoengineering are made.

Governance refers to the structures, processes, and actions through which private and public actors interact to address goals related to whether and how solar geoengineering research or deployment occurs. This includes any system of formal or informal institutions and the norms, rules, laws, regulations, procedures, or voluntary guidelines for deciding, managing, implementing and monitoring actions at any geographic or political scale, from global to local (adapted from IPCC 2022; see also Academic Working Group 2018, 3).

Actors in governance span a wide set of sectors, and is not only about governments. Non state actors especially have an important role to play. These include scientists, academic institutions, funders, civil society organizations, and intergovernmental entities.

Solar geoengineering governance is needed for at least two different levels: research and deployment. Research is ongoing and will involve greater effects on the environment at different scales. Research needs to be responsible, inclusive, and environmentally safe. Deployment of solar geoengineering will involve a wide variety of interests, costs, and benefits. Its effectiveness will need to be monitored and its impacts properly attributed. Governance mechanisms will be needed to ensure that solar geoengineering is used justly. 

Solar geoengineering governance can also be enabling or restrictive. In thinking about research, governance is often thought of only as restrictive measures focused on inhibiting harmful or irresponsible actions. However, it’s important to remember that governance also means processes or actions that can enable better decision-making and better research. This could include actions that make it more feasible, and for the research enterprise to be more inclusive. A few examples across both spaces include codes of conduct, civil society advocacy, and funding.


Justice demands the protection of basic rights, the fair treatment of individuals, and equal opportunity of all to participate in the decision-making processes that govern their lives. 

There are different types of justice: 

Distributive justice is the protection of basic rights and the fair distribution of benefits and burdens across a society.

Procedural justice is equal opportunity to influence the deliberations of governance structures to whom one is subject. It is also genuine accountability for those who exercise power in order to prevent domination or exploitation.

Historical/Restorative justice is atonement for contemporary wrongdoing and reparations for historical injustice.

All three types of justice can be applied to specific issue areas. Issue area justice orients our thinking away from individual culpability and towards social structures that distribute opportunities, benefits, costs, rights, or privileges. Climate justice is the application of these concepts—distributive, restorative, and procedural justice—the domain of climate change and climate policy.

For example: what is the just distribution of the benefits and costs of our emissions behavior and our transition to a carbon-free economy? Who should have a say in climate policy, research, and governance and what institutions have the legitimacy to decide? To what extent do historical emissions represent an injustice and how can rich nations compensate for them? Similarly, how can the nations that are causing negative climate impacts compensate, restore, or make whole those who are suffering them?

Importantly, climate justice is distinct from environmental justice and energy justice.

Environmental justice tends to focus on local environmental issues, such as pollution or conservation and show that negative environmental impacts fall disproportionately on vulnerable communities. Key examples: Landfills or polluting factories are often located amongst disadvantaged communities. 

Energy justice concerns equitable access to sustainable, clean, and reliable energy needed to live decent lives. While clearly related to climate change, it is distinct as there are causes of climate change impacts that are not related to energy provision

Solar geoengineering governance should be designed to ensure that solar geoengineering research and deployment follows the requirements of climate justice. Important questions at the intersection of climate justice and solar geoengineering include: are the benefits and costs of research or potential deployment distributed fairly while protecting the basic rights of the most vulnerable? Do all those affected have an opportunity to participate and have a say in how solar geoengineering will be research, deployed, and governed? Are powerful actors held genuinely accountable for their actions? Are there plans for those who could be harmed by solar geoengineering to becompensated, rehabilitated, or restored?

Read the DSG paper that looks at the justice-based rationale for our work.

capacity building

Capacity building for solar geoengineering governance refers to a sustained process through which individuals, organizations, and societies mobilize and sustain knowledge, skills, tools, and practices that enable their ability to implement and engage in local, national, and international forms of solar geoengineering governance.

Read the DSG paper that looks at previous definitions of capacity building and work in this space to learn more.

Public Engagement

Public participation and/or engagement refers to approaches by which researchers, funding institutions, and other decision-making bodies can aim to inform, understand, draw input from, and empower publics and stakeholders. People can engage in decision-making, such as by weighing in on what policies, laws, or rules should be adopted; and people can also engage in research, such as by providing local knowledge to researchers or by working alongside researchers to interpret the results of a study. 

Authoritative solar geoengineering assessments and governance reports (see our resources page) agree that public engagement is essential for legitimate, inclusive, just, and effective solar geoengineering governance. These reports have argued that not only is involving people in solar geoengineering decision-making the right thing to do, but doing so can lead to better decisions, for example by ensuring that decisions are made with diverse values, perspectives, and forms of knowledge in mind. As philosopher Dr. Marion Hourdequin stated, “research on SRM cannot fully comprehend or take account of the diverse distributive impacts of this technology without robust engagement and input from those affected and their distinctive cultures, perspectives, and relationships to the natural environment.” (Hourdequin 2019, 465-366).

Public engagement is no panacea; when done poorly, it can feel ‘fake’ or symbolic from the point of view of participants; vulnerable or marginalized populations are also often left out. It is also difficult to define the “public”. Even within a single country, there is not one “public”, but rather many publics, with different values, beliefs, and worldviews. DSG supports public engagement activities that are inclusive, particularly of vulnerable groups, and that aim to empower participants, including by providing them with the power to make decisions and by building their capacity to engage in solar geoengineering deliberations. 

civil society

Civil society can be defined in many ways. We understand civil society as an arena for societal deliberation comprised of a network of groups, communities, and voluntary associations that is distinct from the state and that excludes profit-motivated entities. Examples of civil society actors include non-governmental organizations, community-based organizations, and public interest groups.


Inclusion requires improving participation for those who have been disadvantaged, marginalized, and vulnerable through enhanced opportunities, access to resources, voice, and respect for rights. (Adapted from the United Nations Department of Economic and Social Affairs)


Deliberation refers to discussion and processes surrounding decision-making.