On December 12, 2015, the United Nations Climate Change Conference of the Parties (COP21) arrived at a legally binding international treaty to limit the global temperature rise to 1.5°C above pre-industrial levels. Eight years later, the global temperature has already risen by about 1.2° and the UN Environment Programme warns that current policies will lead to a 2.6° temperature rise by the end of the century—called climate overshoot.
Any overshoot, even if temporary, can be catastrophic leading to loss of nearly all coral reefs, reduction of global crop yields and rising sea levels. Some changes could also be irreversible like the Antarctic ice sheet melt. Climate scientists say the risk to biodiversity from temperature overshoot will “arrive suddenly, but decrease only gradually”. There is evidence suggesting that patterns of atmospheric circulation known as Hadley cells—which are already changing, leading to drier weather in the subtropics—may not return to their original state, even if carbon dioxide levels go down again.
But, the question is whether solar geoengineering or Solar Radiation Modification (SRM) technologies, which reflect sunlight back to space, are a viable solution to reduce temperatures. The technologies that are talked about are space-based reflectors, stratospheric aerosol injection, cirrus cloud thinning and marine cloud brightening.
Recently, the White House Office of Science and Technology Policy released a report showing keen interest in SRM tech. Now, the Climate Overshoot Commission, an independent body, has come out with its first report recommending solar geoengineering. Such an interest in solar geoengineering is being viewed sceptically by researchers due to several ‘unknown risks’ associated with these technologies. In the report, the Commission said: “If it were used at large scale, SRM would reduce temperatures within a few years and would have global effects.” It suggested more research and deliberations.
Aarti Khosla, founder of the think tank Climate Trends, told TNIE: “Technological fixes like solar geoengineering have limited applicability, and may discourage countries from pursuing emissions reductions by providing false promises.” She said risks associated with solar engineering have led to a moratorium on climate-related geoengineering under the Convention on Biological Diversity.
The need for tight governance was underscored earlier this year when in a seemingly cynical move, a US startup temporarily relocated operations to Mexico where it released sulphur particles in a rogue experiment that brought an ensuing ban from the country. There are also concerns that Global South countries like India could be used as testing grounds for SRM technologies, as we already see patterns of Global North and wealthy extractive nations seeking to offshore their emissions to the Global South. Prakash Kashwan, associate professor in environmental studies at Brandeis University, said: “It is bit ironical that the report flags potential for transboundary harms of solar geoengineering outdoor research but pays little attention to the potential for severe disruption of monsoons that are the main source of drinking water and irrigation critical to the lives and livelihoods of at least a billion people in South Asia, South-east Asia, and Eastern Africa.”
Prof Joeri Rogelj from Imperial College London says, “The idea that we can easily control climate change in an overshoot scenario should be viewed extremely sceptically. The unknowns of such a world mean that there are no safe bets.” However, in their defence, Frances Beinecke, President Emerita, and member of the overshoot commission said the Commission’s mandate was to examine the different options under consideration for avoiding overshoot. “Even as we explored the various methods (SRM) outlined in the report, it became crystal clear that the only effective means to avoid overshoot is to act now to cut emissions and phase out fossil fuels. ”