The Arctic sea ice is in decline.

You can see the decline in the old 2014 graph below and in the latest sea-ice extent graphs.

This 2014 graph shows the average of the “Area covered by Arctic Sea Ice during September” each year. The sea ice area normally reaches a minimum in September, after its summer decrease, and as it starts its winter increase. The area is in millions of square kilometres. The decline shown in this 2014 graph is continuing.

See the latest Arctic Sea Ice graph. The May 2026 graph showed ice area was decreasing by 12.2 percent per decade.

Arctic Ice Cools the World

“Arctic ice plays an important role in maintaining the Earth’s temperature. The shiny white ice reflects light and heat that the ocean would otherwise absorb, keeping the Northern Hemisphere cool.” (NSIDC)

Arctic Ice-Albedo Heating Cycle Diagram

Diagram: The Ice–Albedo Feedback Cycle Accelerating Arctic Warming.
 

Over a period dominated by this cycle:

• A rise in temperatures melts ice, reducing the area covered by sea ice.
• This exposes ocean water, which is far less reflective than ice, reducing the sunlight reflected from the Arctic back into outer space.
• This increases the amount of the sun’s heat absorbed by the Arctic.
• This further raises temperatures, and the cycle repeats.

The amount of light reflected from a surface is the “albedo” of the surface. Uncovered ice reflects about 85% of incoming light and so has an albedo of around 85%, whereas the albedo of ocean water is around 15%. This difference in reflectivity drives the cycle, and it’s why “albedo” is part of the cycle’s name.

The Heating Cycle is Intermittent

This ice-albedo heating cycle operates intermittently because several of its causal links only function under certain conditions. Consider each causal link:

• An increase in temperature tends to reduce ice cover, but only at certain temperatures. When temperatures are at or below freezing, ice cover does not reduce; it remains constant or increases. This link is intermittent, causing the cycle to pause. Even at higher temperatures, this link is slow because it takes a lot of energy to melt ice. It takes 80 calories to melt 1 gram of ice at 0°C into water at 0 °C. That is as much energy as it takes to boil water, i.e., to heat 20°C tap water to 100 °C.
• A reduction in ice cover tends to reduce sunlight reflection, depending on the amount of sunlight. This link operates most strongly when there is the most sunlight, in mid-summer. The link weakens in low sunlight and pauses the cycle at night because no sunlight means no reduced reflection. Again, this link is intermittent, and the pauses are lengthy in mid-winter when there is no daylight.
• A reduction in reflection tends to increase heat absorption.
• An increase in absorbed heat tends to raise temperatures. For example, when seawater absorbs the heat, it takes roughly 0.95 calories of energy to raise the temperature of one gram of seawater by 1°C.

This cycle is intermittent, as it stops functioning at night and whenever temperatures are below freezing, which certainly happens during the winter expansion of the ice area. (See the graph near the end of this page.)

For much of the year, daily cycles of night and day mean that part of the Arctic is dark while the remainder is sunlit to varying degrees. So, the heating cycle can be active in sunlit areas and inactive in dark areas simultaneously. The cycle’s activity varies with time and place.

Dominant over a period

Over at least the past 4 decades, (1) Arctic sea ice cover has been dropping (see the above graph), (2) Arctic temperatures have been rising, and (3) the ice-albedo heating cycle has been dominant overall and contributing to these changes, supported by other global-warming-amplifying cycles and by humans adding greenhouse gases to the atmosphere.

A dangerous spiral is occurring in the Arctic, with warming causing further warming. The Arctic has warmed twice as fast as the rest of the globe, in part due to this vicious cycle.

Limiting the heating cycle

Humans could limit this vicious cycle, or it could simply run its course:

• Lowering temperatures: Humans might be able to reduce Arctic temperatures by reducing atmospheric greenhouse gas levels. This reduction could allow more heat to escape from the planet, cool the Arctic, and pause the melting cycle.
• Reducing the Arctic’s absorption of sunlight: Nature might be able to do this with massive volcanic eruptions that darkened the globe for extended periods. Humans could theoretically attempt this through large-scale geoengineering that shaded the Arctic: an immense endeavour.
• Exhausting a necessary resource: Arctic ice. If humans do not stop this vicious cycle, it could continue until it ultimately melts all the ice, leading to an ice-free period during the summers. Ice-free summers would have a significant impact on the global climate, as the Arctic would reflect far less sunlight and the planet would lose an important cooling mechanism.

The Ice-Albedo Cooling Cycle

There is an additional layer of intermittency, as this ice-albedo cycle is one of those amplifying cycles that can run in reverse. We have discussed heating caused by the ice albedo cycle, but it can also cause cooling.

Diagram: The Reverse Ice–Albedo Feedback Cycle that can Accelerate Arctic Cooling.

Over a period dominated by this cycle:

• A drop in temperatures creates more ice, increasing the area covered by sea ice.
• This covers ocean water with highly reflective ice, increasing the sunlight reflected from the Arctic back into outer space.
• This reduces the amount of solar heat absorbed by the Arctic.
• This further lowers temperatures, and the cycle repeats.

The cooling cycle is active only when both freezing temperatures and sunlight are present. In the past, the Earth has moved between ice ages and interglacial periods about every 100,0000 years. This ice-albedo cooling cycle contributed to the development and maintenance of ice ages. We live on a dynamic planet.

Currently, the cooling cycle only functions briefly. Overall, the ice-albedo heating cycle is dominant, with temperatures rising and the sea ice area declining. The heating cycle is supported by other global-warming-amplifying cycles and by humans adding greenhouse gases to our atmosphere.

The Arctic has warmed twice as fast as the rest of the globe, in part due to the ice-albedo heating feedback.

Amplifying feedback in general

This ice-albedo cycle suggests several features of amplifying feedback cycles in general.

An amplifying feedback cycle is (1) inactive or dormant when one link is inactive, and (2) active when all its causal links are active at the same time. Considering audio system feedback cycles suggests this too; however, not all cycles are like this.

An amplifying feedback cycle’s activity can vary with time and place, with each place experiencing significant periods of inactivity, i.e., functioning intermittently.

An amplifying feedback cycle and the activities that support it, e.g., other similar amplifying feedback cycles, dominate periods during which each of the cycle’s changes occurs.

I am still thinking through these general ways to describe amplifying feedback cycles and would appreciate comments on them.

Arctic Sea Ice Area: Daily graph

You can see the movement of “sea ice cover” over a year, for each year since 1979. The graph for the current year updates each day, often showing that this year’s ice cover is below the record minimum.

The latest daily “Arctic Ice Area” graphs are on the “US National Snow and Ice Data Centre” (NSIDC) web page.

Here is a photo of this interactive web page on 6 April 2015.

• The graph shows Arctic Sea Ice Extent: the area with more than 15% sea ice, measured in “millions of square kilometres”.
• The dotted green line shows the sea ice area for each day of the record-low year of 2012. The sea ice area was greatest in mid-March 2012. It was lowest in mid-September.
• The blue line from 1 January to 5 April 2015 shows the ice cover for 2015. The 2015 line ends on 5 April, as I took the photo on 6 April.
• The thick black line is the average extent for each calendar day from 1981 to 2010
• The grey area on the graph shows two standard deviations on either side of the average.
• The online NSIDC graph is interactive; e.g., you can click any year in the list on the right to see how ice cover changed that year.

Wind up

The ice albedo heating cycle shows that:

• Simple cyclic causal linkages can produce powerful change.
• Amplifying feedback cycles can generate long-term change as they move between functioning, non-functioning, and even reversing.
• Unimpeded, this heating ice albedo cycle will persist until it exhausts a critical resource, sea ice, and so becomes self-limiting.
• Amplifying feedback cycles can be intermittent.

In today’s Arctic, the evidence is unambiguous. Declining ice cover and rising temperatures indicate that the heating ice-albedo amplifying feedback cycle is dominant overall.

References

A regime shift is taking place as the Arctic sea ice melts (ABC: 13 Jan 2021)

Arctic sea-ice loss accelerates Arctic warming: Scientific American: 2010

Related pages on this site

A note on systems theory, focused mainly on audio feedback

A gambling vicious cycle. based on psychodynamics

Loaded 10 August 2014. Updated 11 June 2026.