In the 1990's, the Membrane Domain started publishing research on human induced climate change. The research team was the first to put forth the hypothesis that global warming is an exponential phenomenon. Up to that point, the scientific community had based their forecasts on a linear event. The Membrane Domain suggested the model was more like a bathtub curve or hockey stick curve.
Since that time, the hypothesis has been proven. One of the main factors are chain reactions that are caused by the result. The chain reactions have been given the name "feedback loops".
"Feedback in general is the process in which changing one quantity changes a second quantity, and the change in the second quantity in turn changes the first. Positive feedback amplifies the change in the first quantity...." (Wikipedia)
An example of a feedback loop is the melting of Arctic sea ice. Methane, one of the most severe greenhouse gases, is trapped under the ice. However, when global warming causes the sea ice to melt, methane is released. When methane is released it intensifies global warming, resulting in more ice melting. In turn, more methane is released causing an acceleration in global warming... and so on.
The Arctic has multiple feedback loops including: enhanced oceanic heating and ice-albedo feedback due to diminishing sea ice, Planck feedback, lapse-rate feedback, and cloud feedback. Sea ice reflects much of the heat. Dark ocean surface absorbs more heat. The warmer temperature melts more ice resulting in warmer ocean temperatures which in turn melts more ice. A study published in the journal Nature found The Arctic has warmed nearly four times faster than the globe since 1979.
Albedo is the reflective nature of snow and ice that measures how much light is reflected without being absorbed when hitting an object (e.g. the fraction of incoming solar radiation that gets reflected back into space). Snow has a very high albedo that reflects most of the light and absorbs very little heat. The snow-albedo feedback loop occurs when the atmosphere gets warmer due to human induced climate change resulting in less snowfall. The less snow reflecting heat back into space, the warmer the earth becomes. The warmer the earth, the less snowfall. The less snowfall, the warmer the earth.
Another example was sited in a report by NASA:
Greenland's snowy surface has been getting darker over the past two decades, absorbing more heat from the sun and increasing snow melt. The feedback loops work like this -- During a warm summer with clear skies and lots of solar radiation pouring in, the surface starts to melt. As the top layers of fresh snow disappear, old impurities, like dust from erosion or soot that blew in years before, begin to appear, darkening the surface. A warm summer can remove enough snow to allow several years of impurities to concentrate at the surface as surrounding snow layers disappear. At the same time, as the snow melts and refreezes, the grains of snow get larger. This is because the meltwater acts like glue, sticking grains together when the surface refreezes. The larger grains create a less reflective surface that allows more solar radiation to be absorbed.
A feedback loop has been created as a result of ethanol in gasoline. Ethanol in gasoline causes an increase in tropospheric ozone. Tropospheric ozone is a result of a volatile reaction that occurs from vehicle emissions, a warm temperature and ultraviolet light. Tropospheric ozone causes tree death and deforestation. The decline in trees lessens the carbon dioxide sink that trees provide resulting in more global warming. More global warming results in more days when the conditions are right for the creation of tropospheric ozone.
There are several feedback loops between brown carbon, lightning, wildfires, and arctic warming. Brown carbon from wildfires warms the arctic. The warmer arctic absorbs more heat causing more wildfires. In turn, more wildfires cause more brown carbon resulting in a warmer arctic. The cycle keeps reinforcing itself as it repeats.
Studies have found lightning and forest fires are creating a feedback loop. Global warming causes more extreme weather events and conditions for lightning. More lightning sparks a vicious cycle, as trees and soil set ablaze release warming CO2 creating more storms and more lightning. The study Forests at Risk Due to Lightning Fires found a sensitivity of extratropical intact forests to potential increases in lightning fires, which would have far-reaching consequences for terrestrial carbon storage and biodiversity. The results show that, on a global scale, lightning is the primary ignition source of fires in temperate and boreal forests.
"What many people may not be aware of is that lightning is the most common ignition source for fires in remote temperate and boreal forests," says Thomas Janssen, research associate at VU Amsterdam. These forests store large amounts of carbon, which is released in the form of greenhouse gases during the fire. The research reveals that 77% of the burned area in intact forest regions outside the tropics is due to lightning fires, and the number of strikes is expected to increase by 11 to 3 % per degree warming with ongoing climate change.
"When a thunderstorm passes through this landscape, there are thousands of lightning strikes, and some hundreds of them start little fires," said Prof Sander Veraverbeke from the Vrije Universiteit Amsterdam, one of the authors on the research paper. "And these can grow together into mega-fire complexes that become the size of small countries. Once these fires are so big, it becomes very difficult to do anything about them."
The biggest feedback loop is water vapor. Humans put CO2 in the air. CO2 is a greenhouse gas, so the earth gets warmer. Warmer air can hold more water vapor soaking up more water vapor from the oceans. Water vapor is a greenhouse gas, so it gets even warmer... rinse (sorry!) and repeat. Another interesting thing is that the precipitation (rain, snow, sleet) intensity is increasing. A Harder Rain is Falling and The Reign of Violent Rain examine a combination of feedback loops created by water vapor.
Tipping points are part of feedback loop systems. A tipping point occurs when a human influenced global warming activity becomes self-sustaining without the human activity. For instance, the mountain glacier loss tipping point has triggered a feedback loop. The ice-albedo feedback loop is an expression of the ability of surfaces to reflect sunlight (heat from the sun). Any loss of ice over a darker surface means the surface will absorb more heat and reflect less heat. This process makes the Earth warmer causing more loss of ice... which in turn causes more warming of the Earth. When a tipping point causes another tipping point to be toppled it is called the The Domino Effect. Mountain glacier loss, the collapse of AMOC, and the dieback of the Amazon rainforest is an example of The Domino Effect.