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
In the Arctic, warming is causing further warming. In this cycle:
- Global warming tends to 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.
- 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.
(See The dwindling Arctic sea-ice on this website)
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, this would tend to increase global heating; however, global temperatures could drop due to a volcanic eruption reducing the amount of sunlight reaching the earth.
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 Tipping points and how they trigger amplifying feedback on this website.
Here are further examples of climate feedbacks.
The permafrost methane feedback loop
See the methane feedback loop on this website
The phytoplankton feedback loop
See the warming of the ocean surface and the phytoplankton feedback loop on this website
The forest fire feedback loop
See fires intensifying climate change on this website
The ice surface darkening feedback loop
- Global heating tends to increase the melting at the surface of an ice sheet, e.g. the Greenland ice sheet.
- This tends to increase the amount of 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 exposed dust will be less reflective than the ice and will tend to increase the absorption of sunlight.
- This tends to increase global heating.
Danger: The Amplification of Global Heating
The risk of allowing the current heating of our planet to continue is that feedback cycles which amplify the current heating could become dominant. They could produce run-away heating, 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.
Many amplifying feedbacks 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
Feedback is a long-established concept that is a central part of “Systems Theory”. You may know about amplifying feedback under other names, like:
- Positive feedback loops
- Self-amplifying feedback
- Vicious cycles
- Virtuous loops, or
- “Deviation amplifying mutual causal processes”. Maruyama used this term in his revolutionary 1968 article on feedback. (Maruyama: 1968: The Second Cybernetics: Deviation Amplifying Mutual Causal Processes)
Non-climate examples of amplifying feedback
- A person speaks into a loud-speaker, and this kicks off a soft hum, which rapidly escalates into that ear-piercing shriek called feedback.
- Something develops a fault, like a crack in the 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.
- 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. A repeating sequence of events can amplify this small initial change. Amplifying feedback is happening when:
- a change,
- leads to more of that change,
- which leads to more of that change …
While amplifying feedback loops tend to change systems, negative feedback tends to prevent change. See the above Maruyama article or Wikipedia.
The importance of amplifying feedbacks led to the name of this web site: “Feedback Reigns”.
- Climate Change Feedbacks (10
minutevideo: UK Meteorology Office)
- Feedback loops point to a very hot 21st Century (Science Daily, 6 May 2006)
- “Initial Drivers of Climate Change”, “Climate Feedbacks” and “Tipping Points”: NASA
- Greenland Reels: Climate Disrupting Feedbacks Have Begun (
Truth Out, 5/3/2015)
Updated: 17 Dec 2020