The following are some key concepts, along with associated definitions and infographics. For more information, see resources and publications.

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 have a global impact.

Intentional: The deliberate manipulation of Earth’s reflectivity is novel and unprecedented.

Sunlight Reflection: Greenhouse gases increase the proportion of the sun’s energy that remains in the atmosphere as heat. To reduce this effect, we must reduce greenhouse gas emissions and invest in removing emissions from the atmosphere. Solar geoengineering could also reduce the amount of sunlight that is absorbed by the Earth’s atmosphere by reflecting it back into space as a complementary approach to reducing global temperatures and addressing a subset of climate impacts.

SG could potentially lessen the burden on the most vulnerable by decreasing temperatures, but it does not address all climate impacts (e.g. it cannot address ocean acidification). It also presents a range of ecological and social risks and challenges that are not fully understood at this stage.

Approaches

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

Stratospheric Aerosol injection (SAI)

SAI would involve inserting small particles into the upper atmosphere, which 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.

Governance

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 – governance 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 would involve a wide variety of interests, costs, and benefits. Its effectiveness would need to be monitored and its impacts properly attributed. Governance mechanisms would be needed to ensure that solar geoengineering is used justly. 

Solar geoengineering governance can also be enabling or restrictive. When it comes to 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

Justice demands the protection of basic rights, the fair treatment of individuals, and equal opportunity for 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—to 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 follow 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 researched, 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 be compensated, 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.

Research

Modeling and simulation refers to using computational methods to predict and analyze the potential impacts, benefits, and risks of solar geoengineering techniques. These simulations help assess the effectiveness, feasibility, and consequences of interventions aimed at mitigating climate change.

Fieldwork involves conducting experiments and observations in outdoor environments to evaluate the practical effectiveness, feasibility, and potential environmental impacts of solar geoengineering techniques. This research provides empirical data to inform models and policy decisions regarding climate intervention strategies.

Social science refers to the interdisciplinary study of the societal, ethical, political, and economic implications of solar geoengineering. This field examines public perception, governance frameworks, equity issues, and the potential impacts of solar geoengineering on human and social systems. Social science involves multiple disciplines and provides critical insights around how to understand, design, and advise on decision-making.

Impacts research focuses on studying the potential environmental, social, economic, and health effects of implementing solar geoengineering. This research aims to understand the broader consequences and trade-offs of these interventions to inform policy and decision-making.

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

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

Deliberation refers to discussion and processes surrounding decision-making.

Climate Tipping Points

Tipping points are critical thresholds in a system that, when exceeded, can lead to a significant change in the state of the system, often with an understanding that the change is irreversible. These are elements of the Earth system in which small changes can kick off reinforcing loops that ‘tip’ a system from one stable state into a profoundly different state. These elements broadly fall into three categories — cryosphere, ocean-atmosphere, and biosphere — and range from the melting of the Greenland ice sheet to the death of coral reefs. Read the Global Tipping Points report for more.

OVERSHOOT

Overshoot refers to crossing important temperature thresholds, namely 1.5 degrees C.

PEAK SHAVING

In the context of solar geoengineering, peak shaving refers to the idea of using SRM techniques to temporarily reduce the intensity of extreme temperature spikes, or “peaks,” caused by climate change. By reflecting a small portion of sunlight back into space, these techniques aim to lower global temperatures or at least prevent them from exceeding certain thresholds during critical periods. This “shaving” of temperature peaks could theoretically reduce the severity of heatwaves or other climate-related extreme events, offering a temporary mitigation while long-term solutions to climate change are pursued.