The Academy of Sciences recommends the implementation of a solar geoengineering research program.

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Present situation of research and treatment of solar energy geoengineering

The report considers three solar geoengineering measures: stratospheric aerosol injection (increasing the number of tiny reflected particles in the stratosphere to increase the reflection of incident sunlight); whitening of ocean clouds (adding particles to the lower atmosphere to increase the reflectivity of low clouds over the ocean); and cirrus thinning (changing the characteristics of high-altitude ice clouds to allow more infrared radiation to escape into space).

(1) stratospheric aerosol injection. A large number of models and empirical evidence show that stratospheric aerosol injection can reduce land surface temperature on a global scale, but there is still a lot of uncertainty about the cooling potential of injection volume, location and aerosol type, and the effects of aerosol increase on atmospheric chemistry and transport, and the resulting regional and local climate impacts.

(2) Ocean cloud whitening. Current studies have shown that in some cases, adding aerosols to ocean clouds can increase cloud reflectivity. However, the scientific community's limited understanding of aerosol / cloud interactions has led to a great deal of uncertainty about where and to what extent cloud albedo has changed, and whether the feedback process will mask or amplify some effects.

(3) Cirrus becomes thinner. Due to the limited understanding of the characteristics of cirrus clouds and the microphysical processes that determine how cirrus clouds change, the effectiveness of cirrus thinning is unclear. Due to these uncertainties, several existing climate models have produced contradictory results for the simulation of cirrus thinning.

So far, the research on solar geoengineering is relatively scattered, and there are still a lot of knowledge gaps and uncertainties in many key fields. There is a need to strengthen interdisciplinary integration in research, to link the natural, social and ethical dimensions, and to enhance public participation. Research on the potential impact of solar geoengineering on ecosystems, human health, political and economic and other social problems is still in its infancy. In addition, the current solar geoengineering research is also lack of coordination and systematic governance mechanism.

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Proposed framework and method of solar energy geoengineering research and research governance

The report recommends the development of a comprehensive plan to manage solar geoengineering research to ensure that it moves forward in a socially responsible manner. The specific recommendations are as follows:

(1) the framework of the research project

The United States should implement a strong combination of climate mitigation and adaptation policies. In addition, in view of the urgency of climate change and the need to fully understand possible responses, the United States Federal Government should work with other countries to establish an interdisciplinary solar geoengineering research program. The plan should be a small part of the overall US research plan to address climate change, focusing on developing policy-related knowledge rather than advancing deployment paths. The plan should: (1) improve knowledge related to decision-making, including the design of future research work; (2) ensure transparency and public and stakeholder participation; (3) coordinate research between federal agencies and outside the United States federal government; and (4) limit technical research directly applicable to deployment to early basic research.

The plan should establish sound mechanisms to involve civil society and other key stakeholders in the design of research programmes and to promote their participation in relevant components of the programme. Key stakeholders include climate vulnerable groups and a number of special groups, including groups from indigenous peoples and the Southern Hemisphere (mainly referring to populations from countries historically underrepresented in global decision-making).

The plan and its results should be regularly reviewed and evaluated by a diversified and inclusive group of experts and stakeholders, including consultations with international counterparts, to determine whether continued research is justified and, if so, how objectives and priorities should be updated.

The "exit ramp" (that is, the criteria and agreements for terminating the research project) should be a clear part of the programme and there is a mechanism for terminating research activities. For example, if the research project may pose unacceptable natural, social, geopolitical or environmental risks, or if the study makes it clear that a particular solar geoengineering technology is unlikely to be effective.

(2) Inter-departmental coordination

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A comprehensive agenda for solar geoengineering research

The agenda of the solar geoengineering research project should include three broad research areas: research background and objectives; impact and technical dimensions; and social dimensions. Under these three categories, it is recommended to focus on the following areas of research:

(1) the background and goal of solar geoengineering research. 1 the way of project development. Design solar geoengineering research programs to maximize the prospects for a wide range of useful results. (2) future conditions. Explore the conditions under which solar geoengineering decisions will be made in the future. 3Comprehensive decision analysis. Understand the uncertainty that affects the decisions related to solar geoengineering, and adopt corresponding strategies. (4) capacity building. Develop the capacity required for all countries to participate meaningfully in solar geoengineering research and research governance activities.

(2) influence and technology dimension. 1Atmospheric process. Understand how the addition of substances to the atmosphere changes the chemical and physical mechanisms of the reflection and propagation of atmospheric radiation. (2) Climate response. Assess how different solar geoengineering methods will affect key climate outcomes. 3other influences. Assess the potential impact of solar geoengineering intervention strategies on the environment and society. 4Monitoring and attribution. Design an observation system (and understand its limitations) to detect, monitor and attribute the deployment and impact of solar geoengineering. (5) Technology development and evaluation. Solve scientific and engineering problems related to hardware, materials and infrastructure.

(3) Social dimension. 1 Public awareness and participation. Explore how to better understand the public's views on solar geoengineering, and how to fairly and effectively involve the public and stakeholders in the research, development and deployment of solar geoengineering. (2) political and economic trends. Explore the impact of solar geoengineering on national and international relations and related incentive structures. (3) governance. Develop effective and adaptable processes and systems to manage solar geoengineering activities. (4) ethics. Incorporate the ethics and justice considerations of current and future generations into solar geoengineering research and research governance.

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Governance mechanism of solar energy geoengineering research

The National Solar Geoengineering Research Program of the United States should operate under a sound research governance mechanism and support the development of international governance mechanisms. Important elements of governance mechanisms include research codes of conduct, public registration studies, periodic project evaluation and review procedures, outdoor experiment licensing systems, intellectual property guidance, inclusive public and stakeholder participation processes, mechanisms to promote international information sharing and cooperation (between research teams and national scientific institutions), and the establishment o