A Geoengineering Series


As we grapple with the urgent challenge of climate change, technology stands as both our ally and, at times, our most misleading mirage – akin to attempting to shield the planet from warming with an umbrella in the face of the sun, or a corset to hold glaciers in place as the ice sheets melt.

Roll the Dice to Save the Arctic?

25 March 2024

By Dr. Robbie Mallett (Research Scientist at UiT The Arctic University of Norway) and Prof. Dr. Julienne Stroeve (Professor at the University College London; Chief Science Officer at Arctic Basecamp) 


The Arctic is warming at nearly four times the global average rate, and its sea ice, ice sheets and permafrost are melting in response. Rapid environmental change affects those who live in the Arctic, disrupting the livelihoods and lifestyles of communities who have contributed comparably little to the climate crisis.  

But Arctic warming also profoundly affects those who live outside the region: for instance, the Arctic Ocean is the most rapidly acidifying ocean on Earth, and this will soon affect fisheries and ecosystems that extend well beyond the region. Retreating sea ice is exposing new trade routes, but also amplifying geopolitical tensions between Arctic and sub-Arctic states. Since 1992 the melting Greenland ice sheet has contributed more than 1.2 cm to global sea level rise, and our historical emissions alone have already committed us to around 25 cm more 

The implications of the Arctic’s environmental crisis are so immediate and so great that proposals to “save the Arctic” by means other than emissions cuts have recently come to prominence. These controversial techniques are often referred to as Geoengineering or Climate Intervention. 

Geoengineering proposals to save the Arctic often have a science-fiction aura, and run the gamut of feasibility. At the niche end of the spectrum is the deployment of underwater curtains to shield floating ice shelves from warm water which is creeping towards them from the deep ocean. Others have suggested pumping millions of tonnes of water onto the surface of the Arctic’s sea ice to thicken it, a concept similar to building ice stupas in the Himalayas, or spreading billions of tiny glass beads on the surface to reflect sunlight (Arctic Ice Project).  

Another proposal is to reduce the intensity of incoming sunlight by launching optically reflective sulphate aerosols into Earth’s stratosphere; this is known as stratospheric aerosol injection (SAI). The method has a natural analogue: particularly explosive volcanic eruptions have historically placed similar aerosols into the stratosphere, and cooling has been observed. As a proposal it has enjoyed some support by high profile climate scientists such as Paul Crutzen and, more recently Jim Hansen. Unfortunately the deployment of these aerosols has never been rigorously tested outdoors, and the presence of stratospheric sulphates has some known drawbacks such as ozone depletion. 

Large uncertainties persist in the full impact of the geoengineering approach on Earth’s key systems. At present, many of these uncertainties are linked to the behaviour and dynamics of Earth’s stratosphere, especially the polar vortex and corresponding impacts on atmospheric circulation. 

Besides the scientific debate around geoengineering, there may soon be a legal one. Global warming above preindustrial temperatures was around 1.26°C in 2022, and many climate scientists now consider it very likely that we will overshoot the 1.5°C limit recommended by the 2015 Paris climate agreement by 2030. However, the specific wording of the agreement advocates “pursuing efforts to limit the temperature increase to 1.5°C”. 

Some will therefore interpret the Paris Agreement as a mandate for geoengineering the climate back to 1.5°C in the case of an overshoot. The two alternatives for returning below 1.5°C would be a massively expensive carbon dioxide removal effort (which some consider a form of geoengineering), or a multidecadal wait for the Earth’s excess carbon dioxide to be reabsorbed by the ocean. Spending several decades above 1.5°C before dropping back down would probably cause some polar tipping points  be crossed, transforming the face of the planet for millennia to come. 

Geoengineering was advocated at several side events of the COP28 climate summit in Dubai last year. More widely, it appears to be gaining traction as a policy option as humanity consistently fails to reduce its greenhouse gas emissions. The risks and potential benefits of geoengineering are numerous and complex, but we would like to emphasise three key points here which are often overlooked: 

  1. Climate intervention approaches such as SAI, glass bead spreading, water pumping and floating curtains can never be a substitute for humanity’s transition to a net-zero world. This is for a simple reason: while humanity continues to emit greenhouse gases, the amount of intervention required every year to keep global temperatures stable will increase until the interventions are themselves unsustainable. 
  2. The methods mentioned above do nothing to combat ocean acidification, which is happening fastest in Earth’s polar oceans. Ocean acidification is detrimental because it disrupts marine ecosystems, destabilising marine food webs and biodiversity. In fact, climate intervention could represent a moral hazard, and encourage additional emissions in the knowledge that they would not raise global temperatures. This would be a disaster for polar marine ecology and biodiversity.
  3. The governance landscape of climate intervention appears much more complex and volatile than the alternative of governing greenhouse-gas induced climate change. While climate mitigation and adaptation efforts via the UN Framework Convention on Climate Change are painfully slow, progress is being made. For example, during winter 2022 renewables in Europe produced more electricity than fossil fuels for the first time. Furthermore, the stresses of climate change and the required responses have not yet caused major geopolitical conflict or war. It is possible that geoengineering by a nation or even a private company would cause such a conflict. For example, the regional effects on the hydrological cycle would be highly contentious.  

Are the risks and side effects of geoengineering a price worth paying to temporarily suppress global temperature rise, one of the most harmful symptoms of humanity’s addiction to fossil fuels? The answer lies beyond the remit of hard science. As scientists in the global north, we are less exposed to climate risks such as heatwaves, food and water scarcity and flooding. 

Any demand that we hold off on geoengineering and instead wait for emission cuts may therefore ring hollow to the 600 million people that have already been pushed out of humanity’s climate niche by rising temperatures. 

But similarly, we also have the least to lose from geoengineering’s risks and side effects. How can scientists from the midlatitudes advocate for SAI when it does nothing to address (and would probably distract from) the acidification crisis in the Arctic Ocean, where ecosystem disruption would disproportionately affect Arctic communities? 

Instead of simply advocating for one side of the debate, policymakers should urgently consult on the matter with those who are most affected by climate change now, and those who would be most affected by geoengineering in the future. These people lie disproportionately in the global south, in low-lying countries, and in Indigenous communities. We are of course all stakeholders in the Earth’s climate. However, it is critical to remember that some hold considerably bigger stakes than others. Before we roll the dice, vulnerable communities must be consulted first. 


Dr Robbie Mallett began his career studying Physics at Oxford University in the UK, before moving to University College London for an MSc in Climate Change. In 2022 he completed his PhD at UCL’s Centre for Polar Observation and Modelling, combining field campaigns to both polar regions with satellite observations and computer modelling. In 2023 Robbie joined the University of Manitoba in Canada and returned to Antarctica, overwintering for eight months while working on the nearby sea ice. He now works at UiT The Arctic University of Norway, and is a fellow of the International Arctic Science Committee. 


Professor Julienne Stroeve is the Chief Science Officer for Arctic Basecamp. Additionally, she is a senior scientist at the National Snow and Ice Data Center, specializing in remote sensing of the cryosphere. Additionally, Professor Stroeve is also affiliated with the University of Manitoba during a seven-year tenure as a Canada C150 Chair, and as a Professor at University College London. Her research groups focus on improving sea ice retrievals using satellites, the impacts of sea ice loss on extreme weather events and northern communities, and future projections of ice conditions. She regularly conducts fieldwork in the Arctic and Antarctic to collect validation data for sea ice algorithms as well as deploy buoys and moorings. Stroeve’s work is regularly featured in documentaries, and at policy meetings. She is passionate about informing policy makers and the general public about the urgency of limiting global warming to less than 2°C. 

Read the full blog series HERE.