![2007 Arctic Sea Ice](https://upload.wikimedia.org/wikipedia/commons/f/f0/2007_Arctic_Sea_Ice.jpg)
Temperatures in the
Arctic
The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...
region have tended to increase more rapidly than the global average. Projections of
sea ice
Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oce ...
loss that are adjusted to take account of recent rapid
Arctic shrinkage
Arctic sea ice decline has occurred in recent decades due to the effects of climate change on oceans, with declines in sea ice area, extent, and volume. Sea ice in the Arctic Ocean has been melting more in summer than it refreezes in the winter ...
suggest that the Arctic will likely be free of summer sea ice sometime between 2059 and 2078. Various
climate engineering
Climate engineering (also called geoengineering) is a term used for both carbon dioxide removal (CDR) and solar radiation management (SRM), also called solar geoengineering, when applied at a planetary scale.IPCC (2022Chapter 1: Introduction and F ...
schemes have been suggested to reduce the chance of significant and irreversible effects such as
Arctic methane release
Arctic methane release is the release of methane from seas and soils in permafrost regions of the Arctic. While it is a long-term natural process, methane release is exacerbated by global warming. This results in a positive feedback cycle, as ...
.
Several climate engineering proposals have been made which are specific to the Arctic. They are usually
hydrological
Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is calle ...
in nature, and principally center upon measures to prevent
Arctic ice loss.
In addition, other
solar radiation management
Solar geoengineering, or solar radiation modification (SRM), is a type of climate engineering in which sunlight (solar radiation) would be reflected back to outer space to limit or reverse human-caused climate change. It is not a substitute for ...
climate engineering techniques, such as
stratospheric sulfate aerosols have been proposed. These would cool the Arctic by adjusting the
albedo
Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...
of the atmosphere.
Background
The Arctic region plays an important role in the regulation of the Earth's climate. Conditions in the Arctic may suggest the existence of
tipping points, including
ice–albedo feedback
Ice–albedo feedback is a positive feedback climate process where a change in the area of ice caps, glaciers, and sea ice alters the albedo and surface temperature of a planet. Ice is very reflective, therefore it reflects far more solar energy ba ...
from melting Arctic sea ice and
Arctic methane release
Arctic methane release is the release of methane from seas and soils in permafrost regions of the Arctic. While it is a long-term natural process, methane release is exacerbated by global warming. This results in a positive feedback cycle, as ...
from thawing
permafrost
Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...
and
methane clathrate
Methane clathrate (CH4·5.75H2O) or (8CH4·46H2O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate, is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amou ...
. The speed of future retreat of the Arctic sea ice is contentious. The
IPCC Fourth Assessment Report
''Climate Change 2007'', the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC) was published in 2007 and is the fourth in a series of reports intended to assess scientific, technical and socio ...
of 2007 states that "in some projections, Arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century." However, the ice has since undergone unexpectedly significant retreat, reaching a record low area in summer 2007 before recovering somewhat in 2008.
A tipping point process could potentially commence as the Arctic region warms, if there is
positive feedback
Positive feedback (exacerbating feedback, self-reinforcing feedback) is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in the ...
with sufficient gain. Tim Lenton suggests that the retreat of
sea ice
Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oce ...
is such a process, and the tipping may have started already. Climate engineering has been proposed for preventing or reversing tipping point events in the Arctic, in particular to halt the retreat of the sea ice.
Preventing such ice loss is important for climate control, as the Arctic ice regulates global temperatures by virtue of its
albedo
Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...
, and also by restraining
methane emissions
Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
from permafrost near the shoreline in the Arctic region. Additionally, the sea ice has a wider regional climatic role since it acts to maintain permafrost in the general region through its ability to insulate cold winter winds from the warm sea.
Building thicker sea ice
It has been proposed to actively enhance the polar ice cap by spraying or pumping water onto the top of it which would build thicker sea ice.
Since ice is an insulator, water on the surface of the ice tends to freeze more quickly than the content below it.
Thickening ice by spraying seawater onto existing ice has been proposed. Sea ice is an effective
thermal insulator
Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...
, and thus freezing takes place much more rapidly on the top surface of the ice sheet than on the bottom. Thicker sea ice is more structurally stable and is more resistant to melting due to its increased mass. An additional benefit of this method is that the increased salt content of the melting ice will tend to strengthen downwelling currents when the ice re-melts.
Some ice in the sea is frozen seawater. Other ice comes from glaciers, which come from compacted snow, and is thus fresh water ice.
If salt water ice forms on top of fresh water ice and melts, it will rapidly perforate the lower layers of the ice sheet since ice melts slower in saltwater than in freshwater. Some have speculated that river water could be used to thicken fresh water ice if this problem is deemed important.
Stratospheric sulfate aerosols
Caldeira and
Wood
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...
analyzed the effect of climate engineering in the Arctic using
stratospheric sulfate aerosols.
This technique is not specific to the Arctic region. He found that ''At high latitudes, there is less sunlight deflected per unit albedo change but climate system feedbacks operate more powerfully there. These two effects largely cancel each other, making the global mean temperature response per unit top-of-atmosphere albedo change relatively insensitive to latitude.''
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Influencing ocean temperature and salinity
It has been suggested that locally influencing salinity and temperature of the Arctic Ocean, by changing the ratio of Pacific and fluvial waters entering through the Bering Strait could play a key role in preserving Arctic sea ice. The purpose would be to create a relative increase of fresh water inflow from the Yukon River
The Yukon River (Gwichʼin language, Gwich'in: ''Ųųg Han'' or ''Yuk Han'', Central Alaskan Yup'ik language, Yup'ik: ''Kuigpak'', Inupiaq language, Inupiaq: ''Kuukpak'', Deg Xinag language, Deg Xinag: ''Yeqin'', Hän language, Hän: ''Tth'echù' ...
, while blocking (part) of the warm and saltier waters from the Pacific Ocean. Proposed geoengineering
Climate engineering (also called geoengineering) is a term used for both carbon dioxide removal (CDR) and solar radiation management (SRM), also called solar geoengineering, when applied at a planetary scale.IPCC (2022Chapter 1: Introduction and F ...
options include a dam connecting St. Lawrence Island
St. Lawrence Island ( ess, Sivuqaq, russian: Остров Святого Лаврентия, Ostrov Svyatogo Lavrentiya) is located west of mainland Alaska in the Bering Sea, just south of the Bering Strait. The village of Gambell, located on t ...
and a threshold under the narrow part of the strait.
References
Further reading
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{{DEFAULTSORT:Arctic Geoengineering
Planetary engineering
Arctic research
Environment of the Arctic
Climate change policy
Climate engineering