A £56.8m programme is funding research, including experiments, to see if some potential approaches to cooling the Earth’s climate could be scaleable, feasible – and safe.
Climate change is likely to cause global temperatures to increase by several degrees by the end of the century, and this could lead to a series of potentially dangerous climate tipping points. The aim of the 21 projects funded by UK research agency ARIA is to explore some of the key climate cooling concepts that could potentially to delay or avert these tipping points.
“Decarbonisation is essential, but our current climate trajectory puts us at risk of triggering temperature-driven tipping points in the coming decades,” explained ARIA’s programme director Mark Symes.
ARIA has now detailed how it will be spending £56.8m on funding research teams working across areas from atmospheric physics, chemistry, and climate modelling to chemical engineering, oceanography, governance and ethics. The projects will use modelling, observations and monitoring, indoor testing - and some small outdoor experiments. It’s these outdoor experiments that have generated the most interest.
The research agency explained that where key questions cannot be resolved by modelling or indoor experiments, these five projects will allow “crucial real-world data” to be gathered responsibly. All the outdoor experiments will be short-term and limited in size and scale so their effects dissipate within 24 hours or are fully reversible, ARIA said.
Of the five projects, one will look at rethickening arctic sea ice, three will explore cloud reflectivity, while one will look at how mineral dusts age in the stratosphere.
For example, one team has been awarded £9.9m to investigate whether deliberately thickening Arctic sea ice during winter can slow summer melt, reduce Arctic warming, and mitigate further ice loss. The experiments in Canada across three winter seasons will involve pumping seawater from beneath the existing ice and spreading it on top to freeze. If the early experiments are a success, then later experiments will aim to cover areas up to 1 km².
Another team of researchers is looking at Marine Cloud Brightening (MCB), which aims to cool areas by enhancing cloud reflectivity using a spray of seawater. This could see small-scale, controlled outdoor experiments over the Great Barrier Reef in years three and four of the £1m-funded 5-year project. These would involve brightening clouds within areas up to 10 km × 10 km, with seawater spraying taking place over five to six weeks, for six to eight hours per day.
A separate £6.1m MCB project aims to develop and test new spray technologies. The first three years will involve modelling, building and testing the bespoke sprayers indoors. Outdoor experiments to test the sprayers’ performance could follow, but would last only a few seconds and creating small plumes of seawater spray just a few hundred metres in size. “Only if these initial tests prove successful and safe might later experiments explore brightening larger cloud areas, potentially up to 10km long and a few hundred metres wide. These tests are inherently benign, replicating natural processes that generate sea spray over the ocean developing spray systems such as those that are already employed to cool crowds with fine mists of water and dampen construction sites to suppress pollution,” the project details said.
Another £2m project will look at cloud brightening with electric charge as an alternative to spraying seawater. “The research aims to determine if carefully managed electrical charges could offer a safe and effective method for enhancing cloud reflectivity,” ARIA explains. The project includes plans for very small-scale - 100 m×100 m - controlled outdoor experiments in the UK during the third year of the project.
Stratospheric Aerosol Injection (SAI) has also been discussed as a potential climate cooling method, but sulfates, the most commonly proposed materials can carry significant hazards in this context, including potential ozone depletion and toxicity, so another of the projects funded by ARIA will look at the properties of non-toxic, non-sulfate materials. As part of this £5.5m project milligram-amounts of materials such as limestone, dolomite, or corundum will be attached to the gondolas of weather balloons. These balloons are likely to be launched from sites in the US or UK and will carry the samples into the stratosphere for periods ranging from hours to weeks. No materials will be released into the stratosphere; the aim is to reveal how stratospheric conditions affect the properties of the materials over time.
“This foundational science is essential to advance understanding of the potential impacts of SAI and for determining if less harmful alternatives to sulfates might exist (and if they might warrant further study in the context of SAI),” ARIA said.
Dr Pete Irvine, Research Assistant Professor, Solar Geoengineering, University of Chicago said that ARIA’s solar geoengineering research programme is the largest single funding effort to date - and will make the UK a world leader in this field.
Climate cooling technologies – also known as Solar Radiation Modification - are still in their infancy and it’s not clear whether they will be effective or what other problems they could introduce across complex weather systems. They also don’t treat the underlying cause of climate change which is tied to the excessive amount of greenhouse gases such as carbon dioxide in the atmosphere. Even if climate cooling can reduce temperatures in the short term, bringing down the amount of CO2 entering the atmosphere – and then actually reducing levels – is seen as the best way of tackling climate change. Beyond this there is the concern that creating technologies to put a break on climate change could actually act as a dis-incentive for countries to push ahead with decarbonisation plans.
However, Professor Stuart Haszeldine, Professor of Carbon Capture and Storage, School of School of GeoSciences, University of Edinburgh, said: “Humans are losing the battle against climate change. Engineering cooling is necessary because in spite of measurements and meetings and international treaties during the past 70 years, the annual emissions of greenhouse gases have continued to increase. The world is heading towards heating greater than any time in our civilisation.”
ARIA emphasised that is not funding the deployment of climate cooling technologies but only aims to see if the suggested approaches work and what their effects are. It added: “ARIA is not funding any activities designed to 'block the sun' or carry out large-scale climate modification. Our programme focuses strictly on foundational research, modelling, and, where necessary carefully controlled, small-scale outdoor experiments to investigate fundamental scientific processes.”
It added: “ARIA is not deploying these technologies, and there is no risk of termination shock.” Termination shock is one of the potential risks of large-scale climate projects; if such projects were implemented and then abruptly halted, there is the risk that this could lead to a sudden increase in temperature again.
More on climate change technologies
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- Unrealistic climate change plans need rethink says Tony Blair
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