Five well-publicized polar geoengineering ideas are highly unlikely to help the polar regions and could harm ecosystems, communities, international relations, and our chances of reaching net zero by 2050.
This is according to a new assessment, published in Frontiers in Science, which looked at five of the most developed geoengineering proposals currently being considered for use in Antarctica and the Arctic.
The polar regions are home to fragile communities and ecosystems, as well as most of the world's ice. Technological 'geoengineering' approaches have been proposed to delay or address the impacts of climate breakdown in these regions.
Yet this new review finds that five of those most publicized polar geoengineering ideas are likely to cost billions in set-up and maintenance, while reducing pressure on policymakers and carbon-intensive industries to reduce greenhouse gas emissions. The proposals were also found likely to introduce additional ecological, environmental, legal, and political challenges.
"These ideas are often well-intentioned, but they're flawed. As a community, climate scientists and engineers are doing all we can to reduce the harms of the climate crisis—but deploying any of these five polar projects is likely to work against the polar regions and planet," said lead author Prof Martin Siegert from University of Exeter.
"If we instead combine our limited resources towards treating the cause instead of the symptoms, we have a fair shot at reaching net zero and restoring our climate's health," said co-author Dr Heidi Sevestre from Arctic Monitoring and Assessment Programme Secretariat.
The proposals
To conduct the new assessment, the researchers looked at five geoengineering proposals that have received the most attention to date:
stratospheric aerosol injections (SAI): releasing sunlight-reflecting particles such as sulfate aerosols into the atmosphere to reduce the sun's warming effect
sea curtains/walls: flexible, buoyant structures anchored to the seabed to prevent warm water from reaching and melting ice shelves
sea ice management: pumping seawater onto sea ice to artificially thicken it, or scattering glass microbeads onto sea ice to boost its reflectivity
basal water removal: pumping subglacial water away from underneath glaciers to slow ice sheet flow and reduce ice loss
ocean fertilization: adding nutrients such as iron to polar oceans to stimulate blooms of phytoplankton—microscopic creatures that draw carbon into the deep ocean when they die.
They measured each proposal against their likely scope of implementation, effectiveness, feasibility, potential negative consequences, cost, and existing governance frameworks that would allow timely deployment at scale. They also assessed each proposal's potential appeal to those vested in avoiding emissions cuts.
According to the review:
Effectiveness and feasibility: none of the ideas were found to currently benefit from robust real-world testing. No field experiments were found to exist for sea curtains or sea ice reflection; SAI had only been tested with computer modelling, ocean fertilization experiments were inconclusive, and glacier water removal had not been demonstrated beyond limited drilling.
The authors note that the polar regions are some of the world's harshest environments to work in, and even simple logistics are challenging to deploy. They assert that the scale of polar geoengineering would require a human presence in the polar regions unlike anything we have considered to date, and say that many of the ideas do not consider these challenges
Negative consequences: each of the five ideas were found to risk intrinsic environmental damage, with sea ice management carrying particular ecological risks, such as glass beads darkening the ice, and water pumps requiring vast infrastructure. The authors also found that the risks of SAI include ozone depletion and global climate pattern change; sea curtains risk disrupting habitats, feeding grounds and the migration routes of marine animals including whales, seals and seabirds; glacier water removal risks contaminating subglacial environments with fuels; and ocean fertilization carries uncertainty as to which organisms will flourish or decline, as well as the potential for triggering shifts in natural ocean chemical cycling
Cost: the authors estimate that each proposal will cost at least $10 billion to set up and maintain. Among the most expensive are sea curtains, projected at $80 billion over 10 years for an 80 km structure. They caution that these costs are likely underestimates, because they are likely to climb higher once knock-on consequences, such as environmental and logistical impacts, are considered
Governance: the authors found no existing governance frameworks to regulate SAI or sea ice management. Sea curtains and glacier water removal would fall under Antarctic Treaty provisions, while ocean fertilization is treated as marine pollution and restricted under United Nations rules. They caution that each proposal would require extensive political negotiation and the creation of new governance structures and infrastructure
Scale and timing: the authors conclude that, even if the proposals offered some benefit, none can be deployed at sufficient scale, fast enough, to tackle the climate crisis within the limited time available
Vested interest appeasement: the authors found that all proposals risk appealing to those seeking to avoid emissions cuts. They note that claims about sea ice management preserving Indigenous Peoples' rights and environments are misleading, and stress that only rapid decarbonization can achieve this without the introducing additional risks.
Split resources
Geoengineering is a divisive topic among experts and affected communities. Some cite large uncertainties in effectiveness, risks of negative consequences, and major legal and regulatory challenges. Others warn against dismissing proof-of-concept research, and argue that geoengineering could buy time while the world cuts emissions.
Although the authors acknowledge the importance of explorative research, they say that continuing to pursue these five polar geoengineering proposals could shift focus and urgency from the deep systemic change needed to cut greenhouse gas emissions. Geoengineering, they argue, therefore risks splitting monetary and research resources when time is of the essence.
"Mid-century is approaching, but our time, money, and expertise is split between evidence-backed net zero efforts and speculative geoengineering projects," said Prof Siegert. "We're hopeful that we can eliminate emissions by 2050, as long as we combine our efforts towards reaching zero emissions."
"While research can help clarify the potential benefits and pitfalls of geoengineering, it's crucial not to substitute immediate, evidence-based climate action for as-yet unproven methods. Crucially, these approaches should not distract from the urgent priority of reducing emissions and investing in proven mitigation strategies," said Dr Sevestre.
They note that while their assessment focuses on the polar areas, other geoengineering ideas, such as marine cloud brightening and space-based solar reflectors, also need to be assessed against these criteria.
"The good news is that we have existing goals that we know will work. Global heating will likely stabilize within 20 years of us reaching net zero. Temperatures would stop climbing, offering substantial benefits for the polar regions, the planet, and all lifeforms," said Prof Siegert.
