Feedbacks

Dangers > Feedbacks

Amplifying Feedback in Any System

Amplifying feedback can occur in most systems.  It can start with a very small change which is then made bigger (amplified) repeatedly, leading to a big change.  For example when:

  • A person says hello into a loud-speaker and this kicks off a soft hum which rapidly escalates into an ear-piercing shriek.
  • An old system decays, like paint on a building: the more the paint cracks, the more moisture gets under the paint, and the faster the paint cracks. Amplifying feedback can destroy an existing  system.
  • A new system is emerging,  like the more you know, the more you can be curious and investigate, so the more you get to know. Amplifying feedback can create a new system.

Amplifying Feedback  in our Climate System

Amplifying feedback is an important feature of our climate system too. For example:

The Arctic Amplification

A dangerous spiral already seems well established in the Arctic, with warming of the Arctic causing further warming.

The Arctic warms, the Arctic ice retreats, and the ocean absorbs more of the sun’s rays, so the Arctic warms further.

Diagram: The Arctic Ice Feedback Cycle
Diagram: The Arctic Ice Feedback Cycle

This is an amplifying feedback cycle in which: (1) an increase in temperature melts ice, decreasing the area covered by sea ice and so increasing the area of exposed ocean. (2) This decreases the reflection of sunlight as ice is far more reflective than the newly exposed ocean. (3) This reduced reflection increases the sunlight that is absorbed by the ocean. (4) This increases the temperature, amplifying the original increase in temperature and melting more ice so the cycle tends to repeat.  (Discussed in more detail on the page: Evidence > Arctic Ice )

The Dangers of Warming and Amplification

By allowing the current warming of our planet to continue, we risk setting off feedback cycles which amplify the current warming.

These feedbacks could come to dominate our climate, producing run-away warming, which would continue even if humans stopped burning all fossil fuels.

When a loud-speaker goes into “feedback”, you can quickly turn it off.  Unfortunately, the earth’s climate does not have an off switch.

We have co-evolved with our climate, so our current climate system suits human beings and the rich diversity of life on our planet.  We need to protect our current climate system because:

  • The amplification of global warming threatens to destroy our current climate, and
  • We do not know what climate system could be created by this amplification of warming.  It could be radically different.  It could be too hot for humans to stay alive.

Here are some other climate feedbacks that could amplify the current warming:

Methane release from permafrost

There are vast quantities of methane trapped in the Arctic permafrost.  The carbon in this methane is about twice as much carbon as the carbon that is now in the atmosphere.  Permafrost is normally permanently frozen ground. But climate change has caused permafrost to melt at an unprecedented rate. The ground buckles and sinks, causing trees to list at extreme angles.
(Drunken Trees: Signs of Climate Change: National Geographic: Broken Link)

Fallen trees after the permafrost melted in Fairbanks, Alaska in 2004 (National Geographic)
Fallen trees after the permafrost melted in Fairbanks, Alaska in 2004 (National Geographic)

Thawing permafrost can cause worrisome damage to forests, buildings, roads and sewerage.  It also releases methane that has been trapped in the ice, adding to the greenhouse gases in the atmosphere.  This can form an amplifying feedback cycle.  Methane is about 25 times more potent as a greenhouse gas than carbon dioxide.

(A Thawing Rotting Arctic: US National Snow and Ice Data Centre NSIDC)

This diagram shows how warming can lead to more warming.

Diagram: The Methane Release Feedback Cycle
Diagram: The Methane Release Feedback Cycle

In this amplifying feedback cycle: (1) an increase in temperature melts permafrost. (2) This releases methane. (3) This increases the greenhouse gases in the atmosphere. (4) This increases global temperatures, amplifying the original increase in temperature and melting more permafrost to continue the cycle.
Arctic soil thaw may unleash runaway global warming (Scientific American, 2008)

Methane Release from under Cold Sea Floors

There are even more vast quantities of methane held as “methane hydrates” under cold sea floors.  There could be more carbon in these methane hydrates than the carbon in our entire coal, oil and natural gas reserves.

The current warming of our planet could lead to the destabilization of these hydrates and the release of this methane leading to another feedback of warming leading to further warming.

“Billions of tonnes of the greenhouse gas methane are trapped just below the surface of the East Siberian Arctic shelf. Melting means the area is poised to deliver a giant gaseous belch at any moment  – one that could bring global warming forward 35 years and cost the equivalent of almost a year’s global GDP”
Arctic release of methane could cost $60 trillion (New Scientist, July 2013)

The current warming could lead to methane release dominating our climate, with spiralling global warming, even if humans stopped burning all fossil fuels.

Warmth Amplifying Feedback Cycles

This site has detailed the amplifying feedback cycles formed when warming leads to:

  • Melting of Arctic ice, leading to reduced reflection of sunlight, leading to further warming.
  • Melting of Arctic permafrost, leading to the release of methane, leading to further warming.
  • Destabilisation of sea floor methane hydrates, leading to the release of methane, leading to further warming.

Unfortunately, there are many other warmth amplifying feedback cycles, such as :

  • Warming leads to the melting of the surface of the Greenland ice sheet, leading to an increase in dark coloured dust on the surface of the ice (this dust originally fell onto the glacier in snow and was contained in ice before it melted), leading to reduced reflection of sunlight, leading to further warming.
  • Warming contributes to forest destroying fires, leading to reduced consumption of CO2 by forests, leading to an increase in CO2 in the air, leading to further warming.
  • Warming leads to warmer oceans, leading to increased areas of nutrient poor sea surface, leading to less algae, leading to less draw down of CO2, leading to increased CO2 in the air, leading to further warming.

There may not be any climate dynamic that effectively resists  the current warming

James Lovelock’s book, “The Revenge of Gaia” ( 2006, p 35) identifies a couple of climate dynamics that might be able to limit temperature increase, stating that we don’t know enough about these processes.

Lovelock is concerned as the observed rate of global warming suggests that there is NO global climate dynamic that will limit temperature increases and so retain a climate  that is safe for life as we know it.

Lovelock notes that the current levels of methane and CO2 in the atmosphere are comparable to that caused by natural releases of these gases fifty-five million years ago. At this time, temperatures rose between 5 and 8 degrees C, with consequences lasting 200,000 years.

We do not know whether a climate dynamic will emerge to limit temperature increases to a safe level. This is one area of  scientific uncertainty.

We know of many amplifying feedbacks that could cause runaway climate change. They pose a real risk for the global economy, political stability, human health and our environment.

Stop the juggernaut of climate change while we can

Particularly the retreat of the Arctic  sea ice is a clear sign that the juggernaut of climate change is picking up speed.

No Problems
No Problems

We need to leap for the brakes before we reach a cliff edge.  We need to stop before a tipping point at which some amplifying feedback cycle becomes dominant and leads to unstoppable, run-away warming.

 

Feedback is a well established concept

If feedback is a new concept for you, you might be wondering whether it is some new-fangled, wonky concept.  It is not.

Feedback is a well established concept that is a central part of “Systems Theory”.

You may know about amplifying feedback under other names, like:

  • Positive feedback loops
  • Vicious cycles
  • Virtuous loops, or
  • “Deviation amplifying mutual causal processes”,  which is what Maruyama called it in his revolutionary 1968 article on feedback

(Maruyama: 1968: The Second Cybernetics: Deviation Amplifying Mutual Causal Processes)

Negative Feedback

While amplifying feedback loops tend to change systems, negative feedback tends to prevent change.  See the above Maruyama article or Wikipedia.
https://en.wikipedia.org/wiki/Negative_feedback

Feedback Reigns

The importance of amplifying climate feedbacks led to the name of this web site: “Feedback Reigns”

Move to the Next Page

Leave a Reply

%d bloggers like this: