Scientists in the UK have received government funding of almost €70 million to pursue geoengineering projects aimed at artificially cooling the Earth, in an attempt to slow the progression of climate change – but the projects are causing controversy in the scientific community.
Geoengineers at the Advanced Research and Invention Agency (Aria), could try to thicken the Arctic ice pack by injecting seawater into the frozen blocks, under the programme Exploring Options for Actively Cooling the Earth.
Another project could see them attempt to make clouds more reflective by pumping reflective particles into the upper reaches of the skies to limit solar radiation.
"Climate change, largely caused by anthropogenic greenhouse gas emissions, could cause the global temperature to increase by several degrees by the end of the century, precipitating climate tipping points with serious consequences," said the programme's director Mark Symes.
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"The solution to this problem is to cease the burning of fossil fuels and to eliminate excess greenhouse gases from the atmosphere. However, lowering atmospheric greenhouse gas levels – even under the most aggressive scenarios – may not happen fast enough to prevent the onset of tipping points."
Aria proposes small-scale, controlled, geographically confined outdoor experiments on approaches that might help reduce global temperatures, and could give mankind more time to adapt to the consequences of climate change.
"[The experiments] are not meant to be stepping stones to deployment," Symes added. "The research conducted in this programme should allow us to provide critical – and currently missing – real-world data to scientists and society on what the options are for actively cooling the Earth, how such approaches might work, and what the consequences of their use might be, allowing better-informed assessments of their risks and benefits."
Experiments
As well as thickening Arctic sea ice blocks to make them more reflective, projects which could lead to field experiments include marine cloud brightening (MCB) and stratospheric aerosol injection (SAI).
One proposed MCB experiment is to spray a fine mist of natural sea water into the atmosphere from a coastal location in the UK and then analyse whether this brightens clouds and increases their reflectivity.
An example of an SAI project is putting a small amount of natural mineral dust in a weather balloon and sending it high into the atmosphere to see how it responds in that environment.
Aria researchers say that no outdoor experiments will be conducted before the public has been consulted. And when they are held, they will be closely supervised and limited.
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Controversy
However, Aria's planned projects have coincided with a burgeoning campaign for an international agreement not to use solar geoengineering.
"Conducting small-scale experiments risks normalising highly controversial theories and accelerating technological development, creating a a slippery slope toward full-scale deployment," said Mary Church, geoengineering campaign manager at the Centre for International Environmental Law.
"Solar geoengineering is inherently unpredictable and risks breaking further an already broken climate system," she added.
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As the 79th United Nations general assembly and New York Climate Week drew to a close last September, countries across Africa, Europe, Latin America and the Pacific joined more than 500 academics and 2,000 civil society organisations to signal their support for bans on tampering with the atmosphere.
"Solar geoengineering deployment cannot be fairly governed globally and poses unacceptable risk if implemented as a future climate policy option," reads an open letter calling for a ban on such experiments.
"An international non-use agreement on solar geoengineering would be timely, feasible, and effective," the letter added. "It would inhibit further normalisation and development of a risky and poorly understood set of technologies."
"The UK government risks triggering a costly, dangerous and distracting race to develop technologies that should never be used," Church echoed. "Even experimenting with these technologies could further destabilise an already tense geopolitical context."
Global average temperatures in 2024 were 1.6C above pre-industrial levels, temporarily exceeding the target set by the 2015 Paris Agreement.
Current trajectories show the world passing 1.5C of long-term warming by the end of the early 2030s.
