A controversial technology with the potential to control the global climate is gaining interest in India.

The technology in question, solar geoengineering, is a proposal to cool the earth by reflecting some of the sun’s radiation back into space. The repercussions of this technology on the earth’s natural systems, as well on global governance, have led to widespread resistance to its experimentation.

But Indian scientists are beginning to show an interest in researching the implications of solar geoengineering, prompted by global discussions that have intensified in recent years. By most estimates, global warming is slated to cross 2.6 degrees by the end of the century. Increasingly, expert bodies are considering the possibility of deploying solar geoengineering as a temporary, emergency measure if global warming reaches critical levels and the current techniques of carbon dioxide mitigation don’t deliver.

Solar geoengineering scholarship has spurred an expert review of the technology by the United Nations Environmental Programme, which was published last year. The Overshoot Commission, an independent high-level body evaluating global climate actions, also called for more discussions and research on solar geoengineering.

The question of whether solar geoengineering, also known as solar radiation modification (SRM), could be fairly deployed and governed, and the anxieties about its unintended consequences, are reasons why there continues to be strong opposition to the technology. At the recently concluded Conference of Parties under the UN Biodiversity Convention, countries agreed to continue a moratorium on geoengineering technologies.

“This is a big win for the climate justice movement, peoples and communities. With the climate and biodiversity crisis worsening with each passing day, it’s time to focus on real climate solutions that address the root cause of climate change and biodiversity, and not geoengineering technofixes,” said Coraina de la Plaza, Global Coordinator of the NGO Hands Off Mother Earth Alliance, in a statement. “At the upcoming UNFCCC COP29, we hope governments will take this historic decision into account and not push for false solutions like geoengineering to be part of discussions,” she added.

How solar geoengineering could impact monsoon

The most widely studied method of SRM involves injecting sulphate aerosols – tiny particles consisting of compounds of sulphur – into the stratosphere, which then block a fraction of solar radiation and reflect it back into space. This method mimics the dimming effect that volcanic reactions produce when an eruption spews reflective sulphates into the atmosphere, resulting in cooling. Other methods, such as marine cloud brightening, propose injecting a salt spray in shallow marine clouds so they become more bright and reflective.

In a paper published in July 2024, Govindasamy Bala, an atmospheric scientist at the Indian Institute of Science, along with two other researchers, investigated what effect releasing sulphate aerosols at different altitudes might have on tropical rainfall in South Asia and the rest of the world. Bala is among India’s foremost scientists leading research into solar geoengineering, having published one of the first papers modelling the global impacts of solar geoengineering in 2000.

The 2024 study modelled impacts of sulphate aerosol injection at three different altitudes in the lower stratosphere, and found that in each scenario, global and tropical mean precipitation decreased irrespective of height. More than precipitation, temperature was sensitive to changes in altitude, with more surface cooling occurring for higher altitudes of aerosol injection.

Sulphate injections have the potential to offset global heating by blocking the sun’s radiation, but reductions in precipitation may not be proportionate, Bala explained. Greenhouse gases like carbon dioxide, which are responsible for global warming, inhibit the ability of heat to leave the earth’s atmosphere. Solar radiation modification, on the other hand, inhibits the amount of heat coming into the earth. Since these two mechanisms are different, the impacts they have on the earth’s natural systems vary too. 

“If you offset the increase in global warming exactly, you won’t actually offset the increase in global mean precipitation exactly. Instead, it will be over corrected, meaning the reduction will be more,” he said, adding “This is because the global hydrological cycle is more sensitive to sunlight than to carbon dioxide.”

David Keith, Professor and Founding Faculty Director of the Climate Systems Engineering Initiative at the University of Chicago, said the study was “beautifully written” and that it was consistent with the findings of existing research. “In a way, the big news here is that there’s no news. From a public policy perspective, this paper’s findings don’t present anything we don’t already know,” he said. “In the last 25 years of research, the evidence seems to get stronger that these technologies really could reduce some key climate risks without having a big additional risk of their own.”

The implications and tradeoffs of using solar geoengineering are significant for a country like India – where hundreds die in heat waves every year, but whose agrarian economy depends primarily on rainfall. Proponents say the hydrological impacts can be calibrated so as to offset some degree of warming without disrupting rainfall patterns dramatically. “No one is suggesting we release a large amount of sulphates to bring down temperatures all the way back to pre-industrial levels,” said Keith, adding, “What would be more useful is to start very slowly and gradually to reduce temperatures by half a degree or one degree by late this century.”

In part, the excessive reduction in precipitation from solar geoengineering is caused by the nature of the sulphate aerosol itself. While they reflect sunlight, they also absorb some amount of heat, causing a slight heating effect within the stratosphere. “This heating not only affects the hydrological cycle. There is a circulation in the tropical stratosphere called the quasi biennial oscillation, and the heating could destroy that,” said Bala. The quasi biennial oscillation is a wind circulation that strengthens winter in the Northern Hemisphere.

There are dimensions of sulphate aerosol injection that are not yet well understood – such as how the size and distribution of aerosols might affect impacts, which need further study.

A growing interest

The paper co-authored by Bala was supported by the Degrees Initiative, an organisation that works towards building the capacity of developing countries to conduct their own research on SRM. The vision of the organisation is to have experts from every region in the Global South “play a central role in the evaluation and governance of SRM.”

“When we first held meetings with interested countries, climate experts would say they wanted local researchers to report on the local impacts of SRM,” said Andy Parker, CEO of the Degrees Initiative. “We received 75 high quality applications for six grants in the first year of launching our grant programme, which indicated huge interest among countries in the global south. We ultimately increased it to eight grants to try and meet this demand.”

The concept of solar geoengineering has been studied for decades, but most research on the topic has been generated by richer countries in the West. The United States leads in funding solar geoengineering research, followed by the United Kingdom and Germany, as per a 2018 analysis. Civil society groups and governments have expressed concern that the imbalance of research between the Global North and South could influence bargaining power when it comes to making decisions about deployment.

Bodies like the Degrees Initiative, that seek to close this gap, have emerged over the last 10 years, in the aftermath of the Paris Agreement. Even as they seek to platform voices and research from the Global South, these groups have drawn criticism from activists for “covertly” attempting to build consensus on the use of solar geoengineering. The Alliance for Just Deliberation on Solar Geoengineering (DSG), based in the United States and founded in 2023, is another such organisation, whose mission is to “empower people to formulate their own perspectives on solar geoengineering research and potential deployment, rather than boxing them into existing narratives.”

“We don’t tell scientists what they should research, and we don’t tell them which models to use either. We believe in letting scientists pursue the questions they see as most relevant for their regions,” Parker told Mongabay India.

In India, a small-scale survey among 30 climate change experts, conducted by the U.S. based NGO Resources for the Future, found that a majority of respondents saw research on solar geoengineering as an area in need of government support. The foremost preference was to scale up climate modelling research “to be on par with developed countries”. Respondents also felt India should have a national policy on solar geoengineering, saying there is a need for “regulation, transparency, stakeholder consultation, public disclosure, and monitoring.”

According to Bala, who was also part of the group conducting the survey, solar geoengineering is still a “fringe topic” among researchers in India, but he expects it to become a more mainstream topic when climate impacts escalate.

There is also interest in understanding the social aspects of SRM. Researchers at The Energy and Resources Institute (TERI) plan to study how perspectives on the governance of solar geoengineering are evolving in India and South Asia – research that is again supported by the Degrees Initiative. “We want to have a sense of how climate policy researchers and international relations researchers, some of whom represent government interests, view the issue of solar geoengineering use,” said Manish Shrivastava, a senior fellow and associate director at TERI who will lead the project for the next two years.

The aim, Shrivastava said, is to explore whether concerns raised by these groups are consistent with negotiation processes under multilateral agreements like the United Nations Framework Convention on Climate Change (UNFCCC), where the topic of solar geoengineering has largely been absent.

In a meeting in February, under the United Nations Environmental Assembly, India agreed with a proposal to set up an expert committee on solar geoengineering, arguing that the committee should strictly focus on assessing scientific research and not the social, legal, security, and geopolitical risks involved. The resolution was put forward by Switzerland, and supported by the U.S. and Japan. “SRM technologies are being researched in different parts of the world. We need to understand how it is progressing and need to integrate (that) under the process of UNFCCC,” India reportedly said during the meeting.

African countries opposed the resolution entirely, calling for a ban on its use. “SRM, management, or manipulation poses severe and maybe even existential risks to Africa and to the world,” the African group said during talks, a motion that was supported by Pakistan, Mexico, Brazil, Fiji, and Vanuatu, among several other countries.

The proposal was ultimately withdrawn because countries couldn’t agree on how to proceed.

Geopolitical risks

With concerns spanning the scientific, ethical, and political ramifications of solar geoengineering, large scale deployment is still a distant possibility. Among the most vexing questions has to do with whether deployment can be equitable and just.

“What we need is to make transformational changes to our systems and reduce emissions, but instead this is a techno fix with so many uncertainties that risks maintaining the status quo,” Dhanashree Jayaram, Assistant Professor of Geopolitics and International Relations at the Manipal Academy of Higher Education, told Mongabay India.

Jayaram is a signatory to and a coordinating member of the Solar Geoengineering Non Use Agreement. The Agreement is an open letter signed by hundreds of scientists calling for a commitment to five core tenants: no public funding for the development of solar geoengineering technologies, no outdoor experiments, no patents on the technology, no deployment, and no support in international institutions. “Given the anticipated low monetary costs of some of these technologies, there is a risk that a few powerful countries would engage in solar geoengineering unilaterally or in small coalitions even when a majority of countries oppose such deployment,” says the Agreement.

The cooling effect brought on by sulphate aerosol injection lasts in the atmosphere for between a year and two years, which means aerosols would have to be released periodically to sustain the effects of cooling. An uneven release of aerosols over the northern and southern hemispheres could lead to uneven impacts over these geographies. “This is a technology that needs serious deliberation, even more than carbon dioxide removal, because people with this technology can potentially control the global climate,” said Bala.

According to the Non Use Agreement, existing processes under the UN are “incapable of guaranteeing equitable and effective multilateral control over deployment of solar geoengineering technologies at planetary scale.” Despite conventions like the UNFCCC being founded on the principles of equity, rich countries have defaulted on climate finance payments and continue to hold a monopoly over climate mitigation technologies that have been inadequately shared with the developing world. “Many developing countries, including India, have seen the push for solar geoengineering as an attempt to circumvent the historical responsibility rich countries have to mitigate climate change,” said Shrivastava of TERI.

Offsetting global warming through aerosol injection also does not address the underlying cause of climate change: Greenhouse gas emissions from fossil fuel use. The overwhelming scientific consensus is in favour of reducing carbon emissions to halt global warming. “If the idea is seriously entertained, fossil fuel companies and high emitting countries will continue to emit,” said Jayaram.

According to Keith, a thorough assessment of all solar geoengineering research is needed in order to inform a policy position on its use and deployment. “There’s a lot of research out there, but what we really need is a good, unbiased, and trusted assessment of the research,” he said.

“India needs to develop a greater understanding of the risks and be aware of the possible ramifications politically,” said Jayaram, adding, “There’s been an uptick in understanding this topic since 2018. It’s important to keep the discussions going in India, because we don’t want to one day wake up and realise we’ve missed the bus, with no decision making power on the rules of engagement,” she said.

Read more: Stop efforts to dim the Sun and cool Earth, say scientists

Banner image: Solar geoengineering is based on injecting aerosol particles into the stratosphere which may form clouds and reflecting some of the sun’s radiation back into space. Image by Bharathnallan via Wikimedia Commons (CC BY-SA 4.0).

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