Amplifying Feedback

The biggest risk of allowing the current warming of our planet to continue is that there are many ways in which warming can cause more warming, which causes more warming, and so on. Here are a few examples of these self-amplifying feedback loops.


The Arctic warming feedback loop

Diagram: The Arctic Ice Feedback Cycle

In the Arctic, warming is causing further warming. In this cycle:

  • Global warming tends increase temperatures in the Arctic
  • This tends to melt ice, decreasing the area covered by sea ice, and increasing the area of darker exposed ocean. (See my page on The dwindling Arctic sea-ice)
  • This tends to decrease the reflection of sunlight, as ice is far more reflective than the newly exposed ocean.
  • This tends to increase the sunlight that is absorbed by the ocean.
  • This tends to add to global warming, and the cycle repeats. 

These causal links are tendencies

The causal linkages in these feedback loops are tendencies or likely outcomes. For example, when the area of reflective ice in the arctic drops, suggesting an increase in global warming, global temperatures could drop due to a large volcanic eruption which reduced the amounts of sunlight reaching the earth.

Tipping Points

A tipping point is reached when a feedback loop becomes dominant. When many factors influence a system, a feedback loop can become dominant for a while but then lose its ascendancy. For example, a “heating feedback” can be broken by the cooling impact of a large volcanic eruption. See my page on Tipping points and how they trigger amplifying feedback.

Here are further examples of climate feedbacks.


The permafrost methane feedback loop

Diagram of the methane release amplifying feedback loop

See my page on the methane feedback loop.


The phytoplanckton feedback loop

a cycle of warming reducing phytoplankton which increases warming

See my page on the warming of the ocean surface and the phytoplankton feedback loop.


The forest fire feedback loop

Diagram of the forest fire amplifying  feedback loop

See my page on fires intensifying climate change.


The ice surface darkening feedback loop

Diagram of the ice surface darkening feedback loop

Warming increases melting on the surface of an ice sheet, for example on the vast Greenland ice sheet.  This increases the amount of dark dust on the surface of the ice, dust that originally fell onto the glacier and was buried by snow before becoming part of the ice sheet.  This darker surface reduces the reflection of sunlight.  It leads to more absorption of sunlight and to further warming.


Danger: The Amplification of Global Warming

The risk of allowing the current warming of our planet to continue is that feedback cycles which amplify the current global warming could become dominant.  They could produce run-away warming, which would continue even if humans stopped burning all fossil fuels.

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. Much of the planet could become too hot for humans. This poses a real risk for the global economy, political stability, human health, and our environment.

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


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

James Lovelock (“The Revenge of Gaia”: 2006: page 35) is concerned by the observed rate of global warming.  It suggests that there is no global climate dynamic that will limit temperature increases, and 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.

There are 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.


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 long-established concept that is a central part of “Systems Theory”. You may know about amplifying feedback under other names, like:


Non-climate examples of amplifying feedback

  1. A person speaks into a loud-speaker, and this kicks off a soft hum, which rapidly escalates into that ear-piercing shriek called feedback.
  2. Something  develops a fault, like a crack in paint on a house: the more the paint cracks, the more moisture gets under the paint, and the faster the paint cracks. Amplifying feedback can destroy things.
  3. Something emerges,  like a new interest: something catches your interest, so you investigate it more, and become more interested, and turn it into a career.  Amplifying feedback can create new things.

Amplifying feedback can start with a change so small that you cannot notice it.  This small initial change can be amplified by a repeating sequence of events. Amplifying feedback is happening when:

  • a change,
  • leads to more of that change,
  • which leads to more of that change …

Negative Feedback

While amplifying feedback loops tend to change systems, negative feedback tends to prevent change.  See the above Maruyama article or Wikipedia.


Feedback Reigns

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


Links


Updated: 23 August 2019

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.