Antarctica. Credit: SarahNic via Pixabay
An expert assessment of 5 leading geoengineering proposals considered for use in the Arctic and Antarctic has determined none are feasible or likely to succeed, and all are “environmentally dangerous”.
The review, published in the journal Frontiers in Science, warns that further research into these techniques would not be an effective use of limited time and resources which could otherwise be put towards reaching net zero carbon emissions to halt global warming.
Dr Bethan Davies, chair in glaciology at Newcastle University in the UK, who was not involved in the research, says: “It is important that we don’t look to polar geoengineering as some kind of easy solution to the climate crisis, and one that means that we can avoid the worst impacts of failing to meet the net zero goals agreed at the Paris COP[21].
“Fundamentally, the paper shows clearly and far-sightedly that these polar geoengineering interventions are a dangerous distraction from reducing carbon emissions and do not pose a realistic or cost effective solution.”
What is polar geoengineering?
Geoengineering involves large-scale human interventions in the Earth’s natural systems to counteract climate change.
The technological approaches explored in this review interfere in the polar region’s atmosphere, oceans, sea ice or ice sheets to “change heat uptake or distribution around the planet” as a “potential complement to or alternative for reducing emissions”.
One intervention, stratospheric aerosol injections, would involve releasing particles into the upper atmosphere to increase the amount of sunlight reflected out and away from the Earth.
Stratospheric aerosol injection (SAI) in polar environments. The pale blue shading shows the effective time period for SAI in the Arctic. The Inset icons (bottom right) show whether the option has been proposed for Antarctica, the Arctic, or both. Credit: Frontiers
Another would see ‘sea curtains’ installed over tens of kilometres of the ocean floor to prevent warm water from reaching and melting ice shelves.
Managing sea ice, which cools the Earth by reflecting solar energy, could include scattering hollow glass beads to enhance its reflectivity, or artificially thickening the sea by pumping seawater onto the surface or into the air to fall as snow.
Using glass beads as a means to reflect sunlight off polar surfaces. Credit: Frontiers
Basal water removal involves pumping water out from underneath glaciers to slow ice sheet flow and reduce ice loss.
Lastly, ocean fertilisation would require the release of certain nutrients, such as iron, to promote phytoplankton growth and photosynthesis at the ocean surface. This would increase the fixation of CO2, which would sink to the deep ocean to be sequestered once the organisms died.
Ocean fertilization to “draw down” atmospheric CO2. Credit: Frontiers
“Geoengineering has received increased attention in recent years,” says Davies.
“Much of this geoengineering work has lacked adequate and thorough scrutiny from polar scientists and geopolitical experts, which as a community has been slow to respond. This therefore is a very welcome perspective paper that carefully explores the scope of implementation, effectiveness, feasibility, negative consequences, cost and governance.
“The manuscript is thorough – it reviews well the existing shape of the literature. Til now, this has largely been fairly one sided, with most of the scholarly debate focused around those who support or conceptualise these interventions. The answering debate is long overdue.”
More likely to harm than help
The authors estimate that each proposal will cost at least $10 billion to set up and maintain.
“The paper is very clear that [the] interventions … lack evidence that they are effective in achieving their stated goals, are prohibitively costly, and would be challenging to install and govern given the geopolitical complexities of the Arctic and Antarctic,” says Davies.
Each polar geoengineering intervention also poses risk of environmental damage to the region’s fragile ecosystems.
Arctic sea ice thickening to counteract the loss of ice. Credit: Frontiers
For example, stratospheric aerosol injection could lead to ozone depletion, may exacerbate ocean acidification and risks disrupting global climate patterns. Sea ice management may inadvertently darken the ice or have unknown impacts on polar organisms.
Drilling could introduce contaminants into previously pristine subglacial environments.
Subglacial water removal in ice sheets to slow ice flow to the ocean. Drilling to the bed of thick, flowing ice is highly technologically challenging and has never been undertaken for the sustained period required to maintain the drainage of subglacial water. Credit: Frontiers
Sea curtains may act as barriers disrupting habitats, migration routes and interfere with the flow of nutrients. There is also no telling how introducing nutrients would change the composition of phytoplankton species in the ocean.
The authors conclude that none can be deployed at sufficient scale, fast enough, to tackle the climate crisis within the limited time available.
Sea curtains to block warm water from flowing towards ice sheet grounding zones. Credit: Frontiers
Professor Martin Siegert, lead author of the study from the UK’s University of Exeter, says: “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 5 polar projects is likely to work against the polar regions and planet.
“Mid-century is approaching, but our time, money, and expertise is split between evidence-backed net zero efforts and speculative geoengineering projects. We’re hopeful that we can eliminate emissions by 2050, as long as we combine our efforts towards reaching zero emissions.
“The good news is that we have existing goals that we know will work. Global heating will likely stabilise within 20 years of us reaching net zero. Temperatures would stop climbing, offering substantial benefits for the polar regions, the planet, and all lifeforms.”