Geoengineering is not the solution to limiting climate impacts in polar regions

The burning of fossil fuels continues to warm our planet. As climate change intensifies, Antarctica and the Arctic—the vulnerable regions at Earth’s poles—are heating significantly faster than the global average.

Warming at the poles has severe impacts both locally and globally. It is already affecting fragile local communities and ecosystems through the loss of sea ice, glaciers, and ice shelves. The melting of sea ice, which reflects the summer sun’s radiation back into space, allows the ocean to absorb more heat, amplifying global warming. Melting of land ice also contributes to accelerating global sea level rise.

To dampen such feedback loops and avoid the worst impacts of climate change, the Paris Agreement calls for limiting global heating to well below 2°C—and ideally to 1.5°C—above preindustrial levels. According to the IPCC, reaching net zero carbon dioxide emissions by around 2050 is required to have a good chance of limiting warming to 1.5°C.

However given the slow pace of decarbonization and the importance of the polar regions for climate health, some scientists and engineers have proposed technological interventions, known as geoengineering, to mitigate the warming’s impact.

In their Frontiers in Science article, Siegert et al. assess five of the most developed geoengineering ideas currently being considered for deployment in Antarctica and the Arctic.

They conclude that polar geoengineering is not workable, would lead to additional environmental problems, would be prohibitively expensive and would struggle to achieve international agreement. They also offer a word of caution that, to those preferring to continue burning fossil fuels, geoengineering may offer the appealing pretense of a climate solution.

This explainer summarizes the article’s main points.

What is geoengineering?

“Geoengineering”, as used in this paper, refers specifically to large-scale physical interventions in Earth's systems—such as aerosol injections, sea curtains, or ocean fertilization—that aim to mask or delay the symptoms of global heating. It is intended as a potential complement, or alternative, to reducing emissions.

Polar geoengineering refers specifically to interventions in the atmosphere, oceans, sea ice, or ice sheets of the polar regions.

Some definitions of geoengineering include the prevention or removal of carbon in the atmosphere, such as carbon capture and storage (CCS) or reforestation. These are well established and accommodated within the Intergovernmental Panel on Climate Change (IPCC)’s pathways to net zero.

However, scientists are increasingly differentiating between emissions-reduction strategies and geoengineering interventions that alter Earth systems to address the effects of warming. Siegert et al.’s assessment therefore does not include CCS or nature-based solutions (NBS) under the geoengineering umbrella.

Which geoengineering approaches have been proposed for polar regions?

Siegert et al. assessed five polar geoengineering proposals. The chosen ideas are being actively discussed and considered in the scientific and policy communities, as well as in the media. These are:

• stratospheric aerosol injection (SAI): a type of solar radiation modification (SRM) that releases 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 that aim to prevent warm deep water from reaching and melting ice shelves

• sea ice management: the loss of sea ice reduces the amount of solar radiation reflected back to space. This could be countered by artificially thickening ice, or scattering glass microbeads on remaining sea ice to increase its reflectivity

• basal water removal: ice sheets are massive layers of ice that sit on land—such as those in Antarctica and Greenland. They contain ice streams: fast-moving rivers of ice that flow toward the coast, where they can enter the ocean and raise sea levels. Basal water removal pumps out the meltwater beneath these glaciers or builds barriers underneath them, which could increase friction at the base, slow the coastward movement of ice and reduce ice loss

• ocean fertilization: adding nutrients such as iron to polar oceans could promote the growth of tiny marine algae known as phytoplankton. adding nutrients such as iron to polar oceans to stimulate blooms of phytoplankton, which draw carbon into the deep ocean when they die.

What are the risks of geoengineering in polar regions?

Siegert et al. assessed each proposal according to how feasible and effective they are likely to be, as well as their potential consequences, cost, existing legal and regulatory frameworks, scale and timing, and vested interests.

They found that none of the five polar geoengineering ideas hold up to scrutiny as ideas that are workable over the coming decades. Each approach either lacks scientific support, poses serious environmental or political risks, would be prohibitively expensive, or has no clear legal path forward. In some cases, the technologies are so underdeveloped that they remain more speculative than practical. Others could distract from proven solutions like cutting emissions—while appealing to vested interests that hope for fixes to avoid major system change.

The current understanding of these geoengineering approaches relies heavily on computer simulations, with limited real-world testing. This means that scientists require a greater understanding of how geoengineering might work in practice before deployment.

For example, the geological structures beneath the Antarctic ice sheet are poorly understood. This lack of knowledge makes it difficult to accurately predict whether pumping out water would effectively slow glacier movement. In addition, there is significant uncertainty about the environmental impact of polluting polar regions with microbeads, sulfur dioxide, or iron.

To scale up and implement these strategies responsibly could take many decades, even thousands of years in terms of sea ice thickening. As a consequence, these ideas are unviable. A major risk is that investing heavily in geoengineering could divert attention and resources away from proven methods of reducing carbon emissions.

Siegert et al. warn that all five proposals “are extremely unlikely to mitigate the effects of global warming in polar regions and are likely to have serious adverse and unintended consequences.”

What legal protections are in place for polar regions?

The polar regions have complex legal frameworks. While the two poles have significantly different international structures, Siegert et al. suggest that they both “lack the effective governance mechanisms needed to offer protections against the significant potential harms of geoengineering.”

Antarctica is governed through a consensus-based international system of Treaties which means no individual nation holds sole power, complicating the implementation of geoengineering strategies. The Antarctic Treaty includes an environmental protocol requiring comprehensive impact assessments for anything other than minor or transitory activities.

The Arctic is divided into jurisdictions of several neighboring coastal states. Cooperation between states, as well as Indigenous communities, would be needed to accept the consequences of geoengineering projects. For example, as sea ice travels across these borders, glass beads released by one country would eventually pass into the territory of another.

Conflicting national interests could hinder agreement on geoengineering approaches. The approaches may also find opposition from organizations focusing on protecting polar ecosystems or global weather patterns, which some of these proposed ideas are likely to disrupt.

How much would polar geoengineering cost?

All five of the proposals are likely to require hundreds of billions of US dollars to set up and several billions more each year to maintain. This raises significant questions regarding funding sources, especially given competing global priorities. Siegert et al. argue that this budget would be more effectively used to support fundamental climate research and decarbonization efforts.

Beyond the direct costs of the schemes themselves, many approaches will require new polar stations for supply and maintenance. There would also be ongoing costs for monitoring and mitigating undesirable ecological impacts.

What is the best way to protect polar regions from climate change?

According to Siegert et al., decarbonization should remain the key priority for protecting polar regions instead of resorting to physical interventions. They argue that we already possess existing technologies and proven approaches that can be rapidly scaled now to reduce emissions and halt climate change.

By contrast, they argue that geoengineering strategies are “speculative interventions,” and give false hope that decarbonization will not be necessary. This could distract and reduce the pressure on policymakers and carbon-intensive industries to reduce greenhouse gas emissions.