As global heating heads to 1.8C, is it time to consider the ‘Voldemort’ of climate policy?

The world is set to miss the 1.5°C global warming target , and plans are underway for UN climate talks in the Pacific and Turkey.

Climate mitigation – reducing or preventing greenhouse emissions – was once treated as the only legitimate response to global warming. In comparison, climate adaptation – trying to adjust to global warming – was seen as a form of defeatism, or worse, hubris.

But that taboo has long since lifted : our collective failure to prevent climate change means adaptation is now an essential part of climate policy.

Similarly, attitudes to actively removing carbon dioxide from the atmosphere have undergone an evolution. While there are reasons to doubt whether carbon removal can work at scale, Australia’s “net zero emissions” plans rely on these interventions.

Now, the taboo surrounding another controversial form of climate intervention – solar radiation modification (SRM) – appears to be lifting.

What is solar radiation modification?

SRM refers to large-scale technological interventions that reflect a small amount of sunlight back into space, thereby lowering global temperatures. Increasingly called the more benign term ” climate stabilisation “, the proposed methods include space mirrors – satellites equipped with large reflective surfaces – and cloud brightening , where microscopic particles are sprayed into clouds to make them more reflective.

The most commonly discussed SRM technique is stratospheric aerosol injection (SAI) – the release of particles into the upper atmosphere to recreate the cooling effects observed following volcanic eruptions .

SRM is so controversial it’s sometimes called the ” Voldemort of climate policy “. While it could reduce global temperatures, it does not limit carbon emissions, and the ecological effects of deployment are uncertain.

Some critics are worried a potential techno-fix will deter mitigation efforts. Others point out the risks of “termination shock”: once implemented, ending SRM would cause abrupt temperature rise . Scientific research suggests the strong warming experienced since 2023 is likely a case of inadvertent termination shock. When new fuel regulations reduced sulphur dioxide emissions from international shipping, the rapid warming that followed revealed this pollution had, incidentally, been cooling the planet.

At present, SRM inhabits an international and domestic policy vacuum. Many scholars advocate for a ban on both research and deployment, saying these technologies “play God” with nature. We argue a ban on research is no longer tenable.

Why challenge the taboo?

The case for taking SRM seriously does not usually rest on enthusiasm for the technologies, but on global warming’s grim reality . We are approaching planetary tipping points such as significant polar sea ice retreat, the death of the Amazon rainforest and widespread coral reef loss . SRM advocates say it should be viewed as a complement, not an alternative, to mitigation: a means of limiting the extent and duration of temperature overshoot while decarbonisation continues.

Government appetite for this approach is limited and patchy. When the UN Environment Assembly discussed a Swiss proposal for SRM research in 2024 , countries could not agree even on whether and how to regulate research in this area. Countries such as Japan and Saudi Arabia pushed for ongoing research, while vulnerable Pacific and African countries argued against any language that risked endorsing the practice .

Nowhere is the politics of SRM more volatile than the United States. One group of Republicans reject the climate change “hoax” but is so convinced SRM is already happening that many Republican states have criminalised it. Some think tanks advocate SRM as a way to defend ” American Weather Sovereignty “. NASA has an exploratory program investigating space-based reflective dust clouds . For now, the Trump administration has not chosen a side, but it’s easy to imagine a future administration unilaterally blocking, or implementing, SRM.

If we don’t challenge the SRM taboo, self-interested actors are poised to fill the policy vacuum. Elon Musk has recently spoken out in favour of SRM, while ventures such as the US-Israeli startup Stardust are pursuing research without public oversight.

What is Australia’s position?

Australia has no policy on SRM research or deployment, but federal government funds have supported related research into local interventions, including the Reef Restoration and Adaptation Program (RRAP). This trialled the world’s most respected marine cloud brightening research over the Great Barrier Reef.

Existing environmental and climate law might regulate risks posed by small-scale research, but does not consider the larger risks of eventual deployment. With the exception of some ad hoc efforts , SRM research is not subject to any dedicated ethics framework.

The planetary scale of SRM impacts means we urgently need research to consider the geographic distribution of benefits and harms from any deployment, and the security implications of unilateral deployment by any state or private actor.

What should Australia do?

As a trusted middle power, Australia is well positioned to help lead discussions on the future of SRM. At a minimum, Australia should assess the potential impacts of various options on Australia’s climate, agricultural production and natural environment, and develop a public position on research.

Waiting until a foreign government or well-resourced private actor forces the issue would leave Australia reacting to decisions made elsewhere. Instead, we should prepare for the surprises a fast-moving, under-governed field is likely to produce.

As temperature overshoot becomes an inevitability , SRM is emerging as a new element of international climate policy whether we like it or not. We do not argue anyone should deploy SRM, but that we should break the taboo and enable responsible scientific research and public deliberation.