Climate engineering

Climate engineering or climate intervention, commonly referred to as geoengineering, is the deliberate and large-scale intervention in the Earth's climate system, usually with the aim of mitigating the adverse effects of global warming. Climate engineering is an umbrella term for measures that mainly fall into two categories: greenhouse gas removal and solar radiation management. Greenhouse gas removal approaches, of which carbon dioxide removal represents the most prominent subcategory addresses the cause of global warming by removing greenhouse gases from the atmosphere. Solar radiation management attempts to offset effects of greenhouse gases by causing the Earth to absorb less solar radiation.Climate intervention is no substitute for reductions in carbon dioxide emissions and adaptation efforts aimed at reducing the negative consequences of climate change. However, as our planet enters a period of changing climate never before experienced in recorded human history, interest is growing in the potential for deliberate intervention in the climate system to counter climate change. ...Carbon dioxide removal strategies address a key driver of climate change, but research is needed to fully assess if any of these technologies could be appropriate for large-scale deployment. Albedo modification strategies could rapidly cool the planet’s surface but pose environmental and other risks that are not well understood and therefore should not be deployed at climate-altering scales; more research is needed to determine if albedo modification approaches could be viable in the future.Models consistently suggest that SRM would generally reduce climate differences compared to a world with elevated GHG concentrations and no SRM; however, there would also be residual regional differences in climate (e.g., temperature and rainfall) when compared to a climate without elevated GHGs....Models suggest that if SRM methods were realizable they would be effective in countering increasing temperatures, and would be less, but still, effective in countering some other climate changes. SRM would not counter all effects of climate change, and all proposed geoengineering methods also carry risks and side effects. Additional consequences cannot yet be anticipated as the level of scientific understanding about both SRM and CDR is low. There are also many (political, ethical, and practical) issues involving geoengineering that are beyond the scope of this report. Climate engineering or climate intervention, commonly referred to as geoengineering, is the deliberate and large-scale intervention in the Earth's climate system, usually with the aim of mitigating the adverse effects of global warming. Climate engineering is an umbrella term for measures that mainly fall into two categories: greenhouse gas removal and solar radiation management. Greenhouse gas removal approaches, of which carbon dioxide removal represents the most prominent subcategory addresses the cause of global warming by removing greenhouse gases from the atmosphere. Solar radiation management attempts to offset effects of greenhouse gases by causing the Earth to absorb less solar radiation. Climate engineering approaches are sometimes viewed as additional potential options for limiting climate change or its impacts, alongside mitigation and adaptation. There is substantial agreement among scientists that climate engineering cannot substitute for climate change mitigation. Some approaches might be used as accompanying measures to sharp cuts in greenhouse gas emissions. Given that all types of measures for addressing climate change have economic, political, or physical limitations, some climate engineering approaches might eventually be used as part of an ensemble of measures, which can be referred to as climate restoration. Research on costs, benefits, and various types of risks of most climate engineering approaches is at an early stage and their understanding needs to improve to judge their adequacy and feasibility. Almost all research into solar radiation management has to date consisted of computer modelling or laboratory tests, and an attempt to move to outdoor experimentation has proven controversial. Some carbon dioxide removal practices, such as afforestation, ecosystem restoration and bio-energy with carbon capture and storage projects, are underway to a limited extent. Their scalability to effectively affect global climate is, however, debated. Ocean iron fertilization has been investigated in small-scale research trials. These experiments have proven controversial. The World Wildlife Fund has criticized these activities. Most experts and major reports advise against relying on climate engineering techniques as a main solution to global warming, in part due to the large uncertainties over effectiveness and side effects. However, most experts also argue that the risks of such interventions must be seen in the context of risks of dangerous global warming. Interventions at large scale may run a greater risk of disrupting natural systems resulting in a dilemma that those approaches that could prove highly (cost-)effective in addressing extreme climate risk, might themselves cause substantial risk. Some have suggested that the concept of engineering the climate presents a moral hazard because it could reduce political and public pressure for emissions reduction, which could exacerbate overall climate risks; others assert that the threat of climate engineering could spur emissions cuts. Some are in favour of a moratorium on out-of-doors testing and deployment of solar radiation management (SRM). The United Nations is involved in discussions regarding some aspects of the topic. With respect to climate, geoengineering is defined by the Royal Society as '... the deliberate large-scale intervention in the Earth’s climate system, in order to moderate global warming.' Several organizations have investigated climate engineering with a view to evaluating its potential, including the US Congress, the National Academy of Sciences, the Royal Society, and the UK Parliament. The Asilomar International Conference on Climate Intervention Technologies was convened to identify and develop risk reduction guidelines for climate intervention experimentation. Some environmental organisations (such as Friends of the Earth and Greenpeace) have been reluctant to endorse solar radiation management, but are often more supportive of some carbon dioxide removal projects, such as afforestation and peatland restoration. Some authors have argued that any public support for climate engineering may weaken the fragile political consensus to reduce greenhouse gas emissions. The 1965 landmark report 'Restoring the Quality of Our Environment' by U.S. President Lyndon B. Johnson's Science Advisory Committee warned of the harmful effects of fossil fuel emissions, and also mentioned 'deliberately bringing about countervailing climatic changes,' including 'raising the albedo, or reflectivity, of the Earth.' Teller et al. 1997 suggested to research and deploy reflective particles, to reduce incoming solar radiation, and thus to cancel the effects of fossil fuel burning.