Arctic Sea Ice Death Spiral

The Arctic sea ice is in decline, a death spiral. You can see this decline in the old 2014 graph below and in the latest sea-ice extent graphs. See the latest Arctic Sea Ice graph from the US National Snow and Ice Data Centre (NSIDC),

Graph: The Average September Area of Arctic Ice (NSIDC) — Graph: The Average September Area of Arctic Ice: 1979 to 2013 (NSIDC).

This 2014 graph shows the average of the “Area covered by Arctic Sea Ice during September” each year. The sea ice area increases during winter and decreases in summer, normally reaching its minimum in September. The area is in millions of square kilometres. The decline shown in this 2014 graph is continuing.

“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)

On this page:

The Arctic cycle diagram

A dangerous spiral is occurring in the Arctic, with warming causing further warming – and the Arctic is warming twice as fast as the rest of the globe.

Rising Arctic temperatures		Less ice cover

The Arctic absorbs more of the sun’s heat		Less reflection of sunlight back into outer-space

While this cycle is dominant: (1) rising temperatures melt sea ice, (2) reducing the area covered by sea ice, and exposing less-reflective ocean, which (3) reduces the reflection of Arctic sunlight back into outer space, and (4) increases the sun’s heat absorbed by the Arctic, which (5) increases temperatures further, and then (6) the cycle repeats.

Now, reduced ice cover immediately brings less reflection of sunlight and more absorption of the sun’s heat, so this cycle is effectively: (1) temperatures increase, which (2) reduces sea ice cover, which (3) increases temperatures further.

Arctic cycle is intermittent

The cycle can only be active when the conditions are right: (1) the temperature is above freezing, (2) there is daylight, and (3) there is ice to melt. It is active intermittently, more during the long summer days and becomes inactive when temperatures drop below freezing and when there is no light, including the long winter nights.

A central feature of the Arctic is that the ice cover increases and decreases over each year. You can see this in a graph near the end of this page.

Arctic cycle is dominant overall

An amplifying feedback cycle remains dominant when each causal link occurs in sequence, taking its own time without added delays.

Despite the cycle being intermittent, two measured trends confirm that the cycle is dominant overall: (1) Arctic temperatures are rising, and (2) sea ice cover is declining.

The cycle is dominant, 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 this vicious cycle.

Time taken by the Arctic cycle

This circular sequence of causal links takes time, with each physical change in the cycle contributing to this time:

The link between temperature and reduced ice cover is slow, as it takes a large amount 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.
In stark contrast, the next links are instantaneous because as soon as you have less ice cover, you get less reflection of sunlight and more absorption of sunlight.
The link between absorption of sunlight and increased water temperature is gradual: It takes 1 calorie to warm 1 gram of water from 0 to 1 C.

These processes take time.

Inactivating the Arctic cycle

Here are some ways the vicious cycle could become inactive.

Lowering temperatures: Humans might be able to lower Arctic temperatures by reducing greenhouse gas levels in the atmosphere. This 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, then it could run until it limits itself by melting all the ice. This 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.

Arctic cycle can reverse

This is one of those amplifying cycles that can run in reverse.

While the reverse cycle is dominant: (1) lower temperatures cause (2) more freezing and (3) increased sea ice cover, which (4) reflects more sunlight, (5) reduces the absorption of heat, and (6) lowers temperatures, and then (7) the cycle can repeat.

The cycle is active only when both freezing temperatures and sunlight are present. Currently, it will only dominate briefly, as overall temperatures continue to rise.

The Arctic cycle influences seasonal changes in sea ice cover by alternating between active and inactive phases and sometimes reversing. Historically, this and similar feedback cycles contributed to glacial expansion during ice ages, but given the current warming climate, these cooling cycles are unlikely to dominate anytime soon.

Humans could manage this cycle by making it (1) less dominant or (2) active in reverse more often.

Arctic Sea Ice Area: Daily graph

You can see the movement of “sea ice cover” over a year, for each year since 1979. The current-year updates each day, often showing that the current 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 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.
This 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 Arctic ice death spiral demonstrates that:

Simple cyclic causal linkages can produce powerful change.
Amplifying feedback cycles can move between dominance, dormancy, and reverse running, generating long-term change.
Unimpeded, this amplifying cycle will persist until it exhausts a critical resource, sea ice, and so become self-limiting

In today’s Arctic, the evidence is unambiguous. Declining ice cover and rising temperatures show that, despite intermittent dominance, the sea ice death spiral is dominant overall.