Feedback Loops

Feedback loops accelerate global warming.
by Daniel Brouse and Sidd Mukherjee

In the 1990s, the Membrane Domain initiated research on human-induced climate change, challenging the prevailing view that global warming followed a linear pattern. Contrary to this, our research proposed an exponential model, akin to a bathtub or hockey stick curve, which has since been substantiated.

A feedback loop, also called a "Positive Feedback Mechanism", in the context of climate refers to a process where an initial change in a system triggers additional changes that further reinforce and amplify the original change. In other words, the feedback loop amplifies the effects in the same direction as the initial change, creating a self-reinforcing cycle. Positive feedback mechanisms can contribute to the acceleration and intensification of certain climate-related processes; therefore, I hesitate to use the word "positive" in the description because the outcome is quite negative.

An exemplar of a feedback loop is the Arctic sea ice melt. Methane, a potent greenhouse gas, is trapped under the ice. When global warming causes the ice to melt, methane is released, intensifying global warming and causing more ice melt. This cycle perpetuates, contributing to an acceleration in global warming.

The Arctic encompasses various 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, with its reflective properties, plays a crucial role. As ice diminishes, the dark ocean surface absorbs more heat, leading to warmer ocean temperatures, further ice melting, and a continuous loop. A study published in Nature found that the Arctic has warmed nearly four times faster than the globe since 1979.

Albedo, the reflective nature of snow and ice, becomes vital in the snow-albedo feedback loop. Human-induced climate change results in less snowfall due to a warmer atmosphere. Reduced snow reflecting heat back into space causes further warming, creating a self-reinforcing cycle.

Another instance is found in a NASA report on Greenland's changing surface. Darkening over the past two decades due to increased absorption of heat from the sun has intensified snowmelt. During a warm summer, old impurities, like dust or soot, darken the surface as fresh snow disappears. Larger snow grains form when melted snow refreezes, creating a less reflective surface and absorbing more solar radiation.

Several feedback loops involve brown carbon, lightning, wildfires, arctic warming, ice melt, and permafrost collapse. Brown carbon, with a low albedo, absorbs more heat, releasing sequestered carbon and methane into the atmosphere, creating a self-reinforcing cycle.

Studies have identified a feedback loop between lightning and forest fires. Global warming increases extreme weather events, conducive to lightning. More lightning ignites trees and soil, releasing warming CO2, creating more storms and lightning. The Forests at Risk Due to Lightning Fires study reveals the sensitivity of intact forests to potential increases in lightning fires, impacting terrestrial carbon storage and biodiversity.

"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."

More wildfires create more CO2 and more brown carbon that result in more global warming that results in more lightning strikes creating more wildfires resulting in more global warming thawing more permafrost allowing more emissions of CO2 and methane resulting in more warming, creating many more feedback loops.

Water Vapor
The overarching feedback loop is water vapor. Human-induced CO2 emissions warm the Earth, allowing the air to hold more water vapor. Water vapor, a greenhouse gas, amplifies warming, creating a recurring cycle... 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.

Feedback Loop Examples

  1. Ice-Albedo Feedback:
    • Mechanism: As ice and snow melt due to global warming, darker surfaces (such as open water or bare ground) are exposed.
    • Effect: Dark surfaces absorb more sunlight, increasing heat absorption and further warming the area. This leads to more ice melt, creating a self-reinforcing cycle.
  2. Water Vapor Feedback:
    • Mechanism: Warmer temperatures increase evaporation, leading to higher water vapor content in the atmosphere.
    • Effect: Water vapor is a greenhouse gas, contributing to the greenhouse effect. As the atmosphere warms due to increased greenhouse gases, it can hold more moisture, amplifying warming.
  3. Permafrost Thawing Feedback:
    • Mechanism: As global temperatures rise, permafrost (frozen soil in polar regions) thaws, releasing stored carbon dioxide (CO2) and methane (CH4) into the atmosphere.
    • Effect: The release of greenhouse gases from permafrost contributes to further warming, leading to more permafrost thaw and additional greenhouse gas emissions.
  4. Vegetation Loss and Carbon Cycle Feedback:
    • Mechanism: Deforestation and land-use changes reduce the amount of vegetation that acts as a carbon sink, absorbing CO2 from the atmosphere.
    • Effect: With less vegetation, the ability to absorb CO2 is reduced, leading to increased atmospheric CO2 concentrations. This contributes to further warming and can create a positive feedback loop.
  5. Brown Carbon Feedback:
    • Mechanism: Brown carbon, light-absorbing organic carbon with a low albedo, is deposited on ice, snow, or permafrost.
    • Effect: Brown carbon absorbs more heat, accelerating ice melt and permafrost thaw. This releases more sequestered carbon and methane into the atmosphere, contributing to further warming.
  6. Forest Fires and Carbon Release Feedback:
    • Mechanism: Climate change leads to more extreme weather conditions and increased lightning, which can ignite forest fires.
    • Effect: Forest fires release stored carbon into the atmosphere in the form of CO2. More fires contribute to more carbon release, creating a positive feedback loop.

In conclusion, feedback loops, intertwined with tipping points, are integral to the acceleration of climate change. Understanding and mitigating these feedback loops are imperative to addressing the urgent challenges posed by accelerated global warming. Identifying and understanding tipping points is crucial for climate science and policymaking. Crossing multiple tipping points could lead to the Domino Effect, resulting in a much more rapid and severe climate change than currently projected.

* Our climate model employs chaos theory to comprehensively consider human impacts and projects a potential global average temperature increase of 9℃ above pre-industrial levels.

What Can I Do?
There are numerous actions you can take to contribute to saving the planet. Each person bears the responsibility to minimize pollution, discontinue the use of fossil fuels, reduce consumption, and foster a culture of love and care. The Butterfly Effect illustrates that a small change in one area can lead to significant alterations in conditions anywhere on the globe. Hence, the frequently heard statement that a fluttering butterfly in China can cause a hurricane in the Atlantic. Be a butterfly and affect the world.

What you can do today. How to save the planet.

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