Glossary of road map assessment parameters

Description of approach A brief description of the proposed approach to slow the loss of Arctic sea ice and relevant background information.

• Snow is the most reflective material on Earth (Holland et al. 2021), and snow-covered sea ice has a higher albedo than sea ice alone. Some proposals for thickening ice via pumping water include a component of adding snow. Snow could be added directly through a device on or near the sea ice, or potentially through cloud seeding. Snow addition has also been suggested as a strategy to stabilize ice sheets (Feldmann et al. 2019). Snow on sea ice can decrease ice growth, but it also decreases surface ice melt (Holland et al. 2021). As warming continues, and in addition to potential for increased black carbon pollution, snow may melt faster, decreasing the potential of this approach. For an additional approach with the intent of increasing albedo of sea ice see hollow glass microspheres.

Description of what it does mechanistically A brief description of the physical process of the approach and its intended impact(s).

• Expected physical changes (global)
  • No expected global physical changes.
• Expected physical changes (Arctic region)
  • Increases surface albedo, decreases solar absorption, changes insolation of sea ice or other surface.

Spatial extent (size) The spatial size proposed for application of the approach. When possible, this is provided in terms of area (km²).

• Unknown
  • Sea ice and other ice areas in the Arctic.

Where applied – vertically A description of where the approach would be applied in terms of the vertical dimension (e.g., stratosphere, troposphere, sea surface, etc.). For atmospheric approaches, the altitude of application is provided in km.

• Surface of sea ice, glaciers
  • Should not be considered for areas in the Arctic near permafrost, as increased snow on permafrost in the Arctic has accelerated permafrost thawing and increased carbon emissions (Pedron et al. 2023 found that more snow thawed permafrost and led to a four-fold increase in the amount of organic matter available for microbial decomposition).

Where applied – geographically (regional vs global application, is it targeting the Arctic?) A description of where the approach would be applied spatially, indicating if application would be global or would be applied in a specific region or location, and if the approach would be applied within the Arctic region.

• Sea ice and other ice areas in the Arctic

When effective (summer, winter, all year) A description of when in time the approach would produce its desired result.

• Increasing snow volume increases sea ice volume all year; increases in ice area are most pronounced during summer months (Holland et al. 2021).

Impact on

Albedo A description of the approach’s potential impact on albedo - the fraction of light reflected by a surface. Albedo ranges from 0 (no reflectance) to 1 (total reflectance). The impact on albedo will refer to that of sea ice, ocean, land surfaces or for clouds in the atmosphere depending on the approach.

• Increases of 0.27-0.35
  • Adding snow to new ice can increase its albedo from 0.15 to 0.42 (Webster and Warren 2022).
  • Thicker seasonal and multiyear ice with snow has albedo of about 0.85. As snow melts albedo decreases to below 0.5 (Perovich and Polashenski 2012).

Temperature (Arctic region and global)

• Global A description of the approach’s potential impact on global mean surface temperature (°C).
  • Unknown
    • Likely small global impact.
• Arctic region A description of the approach’s potential impact on temperature within the Arctic region (°C).
  • Unknown
    • Possible regional impact.

Radiation budget

• Global A description of the approach’s potential impact on global radiative forcing (Wm^-2). For some approaches, this will be in regard to the surface radiative forcing. For atmospheric approaches, this will be in regard to the top of atmosphere (TOA) radiative forcing. For context, the global energy imbalance from human activities at the top of the atmosphere is 0.90 ±0.15 Wm^-2 (Trenberth and Cheng 2022).
  • Unknown
    • Likely small global impact.
• Arctic region A description of the approach’s potential impact on radiative forcing in the Arctic (Wm^-2). For some approaches, this will be in regard to the surface radiative forcing. For atmospheric approaches, this will be in regard to the top of atmosphere radiative forcing. For context, the global energy imbalance from human activities at the top of the atmosphere is 0.90 ±0.15 Wm^-2 (Trenberth and Cheng 2022).
  • Unknown
    • Possible regional impact.

Sea ice

• Direct or indirect impact on sea ice? This describes if the approach has a direct effect on sea ice or if the approach impacts sea ice indirectly through an impact on another aspect of the climate system, such as temperature.
  • Directly applied to sea ice.
• New or old ice? Approaches may impact sea ice via the formation of new ice, the reinforcement of older existing ice, or both.
  • Both
• Impact on sea ice A description of the approach’s potential impact on sea ice in terms of sea ice extent (m² or km²), area (m² or km²), thickness, or volume (m³), dependent on what is reported in the scientific literature.
  • Increasing snow volume increases sea ice volume in spring and summer months (Holland et al. 2021). Snow can slow ice growth during winter.

Scalability

Spatial scalability Ability to replicate and expand the approach to the appropriate spatial scale to have an impact.

• Unknown
  • Snow production to stabilize glaciers has been deemed not feasibly scalable due to technological requirements and cost (van Wijngaarden et al. 2023). Technology would need to be adapted for a sea ice environment and then scaled.

Efficiency Here we define efficiency as the ratio of impact on radiative forcing to the amount of energy required for the approach ((Wm^-2) J^-1).

• Unknown

Timeline to scalability The estimated time until this approach could be scalable for deployment.

• Unknown
  • Adding snow to sea ice could be logistically challenging in places.

Timeline to global impact (has to be within 20 yr) The estimated time until this approach could have a global impact on climate change in terms of temperature or radiative forcing. Consistently ice-free conditions in September are expected by mid-century, with daily ice-free conditions expected ~4 years earlier (Jahn et al. 2024). Therefore, having a timeline to impact within 20 years might prevent ice-free conditions.

• Unknown

Timeline to Arctic region impact (has to be within 20 yr) The estimated time until this approach could have an impact on sea ice in the Arctic. Consistently ice-free conditions in September are expected by mid-century, with daily ice-free conditions expected ~4 years earlier (Jahn et al. 2024). Therefore, having a timeline to impact within 20 years might prevent ice-free conditions.

• Unknown

Cost

Economic cost The estimated cost of applying this approach ($USD) per relevant metric for the approach when available (e.g., $USD per 1ºC temperature decrease).

• Unknown
  • Cost for snow production to stabilize glaciers in Europe was estimated at $4.3 USD/m2 around 2010 based on ski resort snow production, but this number is likely outdated and is based on availability of freshwater nearby (Abermann et al. 2022).

CO₂ footprint The estimated energy required to apply this approach (CO₂(t)) per relevant metric for the approach when available (e.g., CO₂(t) per 1ºC temperature decrease).

• Unknown
  • Snowmaking would require a substantial amount of water. Making snow from seawater would require a desalination procedure, which can be energy-intensive.
  • A study looking at snow addition onto ice sheets noted that such a procedure would require a significant amount of energy and infrastructure to make the snow (Feldmann et al. 2019).
  • Current snowmaking practices in ski resorts require 3.5-4.3 kWh electricity per m³ (Energi & Kylanalys 2011). 1 square mile of area with 1 m snow would require 2,500,000 m³ of snow and is estimated to require 2.5 GWh (Moseman 2022).

Missing information in this section does not indicate the absence of risks or co-benefits; it simply reflects that sufficient information is not yet available.

Physical and chemical changes

• Co-benefits Potential beneficial impacts to the physical or chemical domain due to application of the approach.
  • Adding snow to thin ice can push the ice below the surface of the water and cause the ice to flood. Under cold conditions, that seawater-flooded snow refreezes, with similar results to ice thickening approaches (Sturm and Masson 2016).
• Risks Potential negative impacts to the physical or chemical domain due to application of the approach.
  • Increased snow on permafrost in the Arctic has accelerated permafrost thawing and increased carbon emissions (Pedron et al. 2023).
  • Blowing snow events, where airborne snow and wind speed pass a threshold, in the Arctic lead to sea salt aerosols in the atmosphere that can have a warming effect during winter and spring (Gong et al. 2023).
  • Adding snow to thin ice can push the ice below the surface of the water and cause the ice to flood, reducing albedo. Under warm conditions, such flooding would speed ice melt (Sturm and Masson 2016).

Impacts on species

• Co-benefits Potential beneficial impacts to species due to application of the approach.
  • Ringed seals use ice to rest, whelp, and nurse young in snow caves. As the Arctic warms, they are becoming more vulnerable to predators in the water and on sea ice as the availability of these resources decreases (Kelly 2022). Adding snow may help maintain these components of their environment.
• Risks Potential negative impacts to species due to application of the approach.
  • Unknown

Impacts on ecosystems

• Co-benefits Potential beneficial impacts to ecosystems due to application of the approach.
  • Adding snow to thin ice can push the ice below the surface of the water and cause the ice to flood. Under cold conditions, that seawater-flooded snow refreezes, with similar results to ice thickening approaches (Sturm and Masson 2016). This may benefit sea ice ecosystems.
• Risks Potential negative impacts to ecosystems due to application of the approach.
  • Some chemicals used in snowmaking contain seeding bacterial and chemical compounds that could have unknown effects in varying environments (Dingle 2018). However, snow can be made without additional compounds, but snow-making efficiency is lower.
  • Adding snow to thin ice can push the ice below the surface of the water and cause the ice to flood, reducing albedo. Under warm conditions, such flooding would speed ice melt (Sturm and Masson 2016), with negative ramifications for sea ice ecosystems.

Impacts on society

• Co-benefits Potential beneficial impacts to society (human communities) due to application of the approach.
  • Unknown
• Risks Potential negative impacts to society (human communities) due to application of the approach.
  • Unknown

Ease of reversibility The ability of the environment and/or climate to revert to a state without application of the approach once an approach is stopped. While this section focuses on reversibility of the environment and/or climate impact, there is also mention of constraints on reversibility due to infrastructure related to the approach.

• Easy
  • It would be relatively easy to cease snowmaking operations.

Risk of termination shock An estimate of the outcome(s) for the environment and/or climate if an approach were to be abruptly stopped.

• Medium
  • For application to sea ice, sea ice would return to levels of albedo and thicknesses for that without snow and return to associated levels of melt.

International vs national jurisdiction A description of whether the approach would be subject to international or national jurisdiction for decisions or regulations related to research activities.

• Applicable to all approaches within Ice Management:
  • For all Ice Management approaches, research and testing could be done within national jurisdiction (territorial seas or Exclusive Economic Zones (EEZs); note that different legal rules apply to territorial seas and EEZs). Scalability may require deployment to additional areas within international waters.  See “Existing governance” for other available information on relevant governance structures.
• Specific to Adding Snow:
  • Mostly national
    • For sea ice, research and testing could be done within national jurisdiction, but scalability may require deployment to additional areas within international waters in the Arctic Ocean. For glaciers and ice sheets, this technique would be deployed within national jurisdiction.

Existing governance A description of existing treaties, laws, and regulations as well as codes of conduct and recommendations that might guide research into the approach. When available, descriptions will delineate existing governance for research versus deployment.

• Applicable to all approaches within Ice Management:
  • The Arctic Ocean is governed by the United Nations Convention on the Law of the Sea (UNCLOS), which includes all Arctic coastal states except the United States. The United States, however, is bound to customary law “including customs codified or that have emerged from UNCLOS” (Argüello and Johansson 2022).
    • UNCLOS and marine scientific research (MSR):
      • MSR is governed by Part XIII of UNCLOS. In general, the right of states to conduct MSR is subject to the rights and duties of other states under UNCLOS (UNCLOS Article 238). There is a duty on parties to promote and facilitate MSR (UNCLOS Article 239).
      • MSR shall be conducted exclusively for peaceful purposes, it may not unjustifiably interfere with other legitimate uses of the sea, and it must be conducted in compliance with all relevant regulations adopted in conformity with the Convention, including those for the protection and preservation of the marine environment (UNCLOS Article 240).
      • States are responsible and liable for damage caused by pollution of the marine environment arising out of MSR undertaken by them or on their behalf (UNCLOS Article 263(3)).
        • Any approaches that involve adding material or energy to the ocean that would cause or be likely to cause damage to the marine environment would constitute “pollution of the marine environment” within the meaning of Article 1(1)(4) of UNCLOS, and States would have a duty to minimize the pollution pursuant to Article 194.
      • National Jurisdiction and MSR under UNCLOS
        • In a coastal state’s territorial sea (12 nautical miles from shore baseline), the coastal state has the exclusive right to regulate, authorize, and conduct MSR.
        • In a coastal state’s EEZ (200 nautical miles from shore baseline), coastal states also have the right to regulate, authorize, and conduct MSR, and MSR by other states requires the consent of the coastal state (UNCLOS Article 246(2)). States ordinarily give their consent, and they are required to adopt rules to ensure that consent is not delayed or denied unreasonably. UNCLOS further specifies grounds for refusing consent, including if the MSR involves introducing harmful substances into the marine environment (UNCLOS Article 246(5)(b)).
      • Areas outside National Jurisdiction and MSR under UNCLOS
        • On the high seas, UNCLOS provides for freedom of MSR (UNCLOS Article 87(1)(f)), but it must be done with due regard for the interests of other States in their exercise of the freedom of the high seas (Articles 87(2)).
        • The high seas are reserved for peaceful purposes (Article 88) and no state may subject a portion of high seas to its sovereignty (Article 89).
  • The United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP) states that Indigenous Peoples have the right to determine how their lands and resources are used, and that to conduct any project affecting Indigenous Peoples’ lands or resources, free, prior and informed consent (FPIC) must be obtained through the Indigenous Peoples’ own representative institutions (UN 2007). 
    • In Canada, the establishment of the National Council for Reconciliation provides a formal mechanism for Indigenous Peoples to hold all levels of government in Canada accountable for implementing UNDRIP, among other reconciliation actions (Bill C-29 2024). Canada maintains a nation-to-nation relationship with Indigenous Peoples (Government of Canada 2024). 
  • The Arctic Council has been called upon as a venue for providing oversight on approaches to slow the loss of Arctic sea ice, or to establish working groups to provide guidance (Bodansky and Hunt 2020, Bennett et al. 2022). If the objective of the approach is to slow the loss of Arctic sea ice, rather than altering global temperatures, the Arctic parties have the primary interest (Bodansky and Hunt 2020). However, the current geopolitical landscape and lack of participation from Russia makes consensus difficult.
  • The American Geophysical Union released an Ethical Framework for Climate Intervention (AGU 2024) to guide responsible research, emphasizing the need for inclusive dialogue and expanded engagement.
  • See Argüello and Johansson (2022) for further details of governance related to ice management.
• Specific to Adding Snow:
  • Unknown
    • Most snowmaking activities are occurring on private land at ski resorts.

Justice Here we define justice related to approaches to slow the loss of Arctic ice through distributive justice, procedural justice, and restorative justice. Following COMEST 2023, we consider questions of ethics through a justice lens.

• Here we define justice related to approaches to slow the loss of Arctic sea ice through distributive justice, procedural justice, and restorative justice. Following COMEST (2023), we consider questions of ethics through a justice lens. Note that this is not an exhaustive list of justice dimensions and as the field advances, so will the related considerations and dimensions.
• Distributive justice Distributive justice is the protection of basic rights and the fair distribution of benefits and burdens across a society. This section answers the question, “are the benefits and costs of research or potential deployment of the approach distributed fairly while protecting the basic rights of the most vulnerable?” (DSG)
  • Applicable to all approaches within Ice Management:
    • If distributive justice is considered, the objective would be that benefits and costs of research or potential deployment of the approach be distributed fairly while protecting the basic rights of the most vulnerable.
  • Specific to Adding Snow:
    • No additional information.
• Procedural justice Procedural justice is the equal opportunity to influence the deliberations of governance structures to whom one is subject. It is also genuine accountability for those who exercise power in order to prevent domination or exploitation. This section answers the question, “Do all those affected have an opportunity to participate and have a say in how the approach will be researched, deployed, and governed?” (DSG)
  • Applicable to all approaches within Ice Management:
    • If procedural justice is considered, people affected by research would have an opportunity to participate and have a say in how the approach will be researched, deployed, and governed.
    • Bennett et al. (2022) suggests an inclusive governance approach that incorporates stakeholder concerns in the design and deployment of approaches and effectively communicates risk. Within the development of such a framework there is an opportunity to prioritize Indigenous self-determination and procedural justice (Chuffart et al. 2023). Note, however, that stakeholders may also include non-local people.
  • Specific to Adding Snow:
    • No additional information.
• Restorative justice Restorative justice is atonement for contemporary wrongdoing and reparations for historical injustice. This section answers the question, “Are there plans for those who could be harmed by the approach to be compensated, rehabilitated, or restored?” (DSG)
  • Applicable to all approaches within Ice Management:
    • If restorative justice is considered, plans would be developed for those who could be harmed by the approach to be compensated, rehabilitated, or restored.
  • Specific to Adding Snow:
    • No additional information.

Public engagement and perception Public engagement describes ways in which “researchers, funding institutions, and decision-making bodies aim to inform, understand, draw input from, and empower publics and stakeholders” (definition from DSG). This section describes how people have been engaged in research for a given approach, as well as capacity building efforts to build knowledge around science and governance. This section also provides information on public perception when available.

• Unknown for Arctic sea ice application
  • Public support has improved over time for application to ski areas (Pütz et al. 2011).

Engagement with Indigenous communities This section describes how Indigenous peoples and communities have been engaged in research for a given approach, as well as capacity building efforts to build knowledge around science and governance.

• Applicable to all approaches within Ice Management:
  • The principle of free, prior, and informed consent (FPIC) in the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP) is the foundation for engagement with Indigenous Peoples.
  • Particular to any potential Arctic research or deployment, The Inuit Circumpolar Council (2022) has published Circumpolar Inuit Protocols for Equitable and Ethical Engagement, which include eight protocols:
    • ‘Nothing About Us Without Us’ – Always Engage with Inuit
    • Recognize Indigenous Knowledge in its Own Right
    • Practice Good Governance
    • Communication with Intent
    • Exercising Accountability – Building Trust
    • Building Meaningful Partnerships
    • Information, Data Sharing, Ownership, and Permissions
    • Equitably Fund Inuit Representation and Knowledge
  • Any meaningful engagement with Indigenous peoples needs to consider context. Whyte (2018) states, “Indigenous voices should be involved in scientific and policy discussions of different types of geoengineering. But, context matters. Geoengineering discourses cannot just be associated with geoengineering to the exclusion of topics and solutions that Indigenous peoples value.”
• Specific to Adding Snow:
  • Unknown