When Positive Feedback is a Bad Thing

Climate change is being accelerated by its own effects.  These are referred to as positive feedback loops.  Here's why: 

In climate change, a feedback loop is the equivalent of a vicious – or virtuous – circle. It's something that accelerates or decelerates a warming trend. A positive feedback accelerates a temperature rise, and a negative feedback decelerates it.

From the National Oceanic and Atmospheric Administration's (NOAA) National Climatic Data Center:  

A positive feedback is a process in which an initial change will bring about an additional change in the same direction... There are also negative feedbacks, processes in which an initial change will bring about an additional change in the opposite direction.

It is positive, rather than negative feedbacks that contribute to abrupt climate changes. In positive feedbacks, a small initial perturbation can yield a large change. Negative feedbacks, on the other hand, stabilize the system by bringing it back to its original state.

A simple and obvious example of a positive feedback loop is melting polar ice.  Polar ice is white(-ish) and it reflects back into space lots of sunlight.  Polar ice has been melting as you know, and uncovering darker water or land underneath.  Solar energy is then absorbed, instead of reflected, and so warming occurs, driving more polar ice melt.  

It's a vicious circle, a feedback loop.  It's positive (in scientific terms) because it is consisting in or characterized by the presence of something (increased temperature) rather than its absence (absence would be negative, i.e., cooling).  

In general terms, there are three kinds of feedback loops

1. ice-related feedback loops, 
2. vegetation-related feedback loops and 
3. feedback loops created by these that include larger influences, like ocean currents (the thermohaline circulation, e.g., the Gulf Stream) and air currents like the jet stream and events like El Ninos and El Ninas 

Here are seventeen, count 'em, seventeen positive feedback loops. Please note that the article I cite lists nineteen and organizes it differently.  I have removed their #11 (their citation has been dropped and I could not confirm the assertion independently) and their #19 is covered by others in my humble opinion.

Ice-related 

• Methane hydrates – methane is a super-powerful greenhouse gas surfacing from the Arctic Ocean 
• Siberian methane 
• Darkening ice in Greenland 
• Cracking glaciers release CO2 
• Release of methane in the Antarctic  
• Greatly accelerated Antarctic ice melt 
• Darkening of ice caused by surface meltwater 

Vegetation-related 

• Amazon drought triggered the release of more methane than the US in 2010 
• Decomposing peat in boreal forests 
• Invasive growth warming soil and thus destabilizing permafrost 
• Forest and bog fires burning at a rate greater than the last 10,000 years 
• Thawing permafrost exposed to sunlight increases bacteria, leading to accelerated thawing 
• Microbes as a contributor within thawing permafrost 

Current-related 

• Warm seawater from the Atlantic ocean further warming the Arctic 
• Canadian floodwater runoff 
• Breakdown of ocean currents like the Gulf Stream 
• Jet stream impacted by reduced temperature range between the poles and the equator 

We’ve got a problem.  Humanity’s modification of the atmosphere through the use of fossil fuels has caused staggering effects that are so far reaching that it may already be too late.  We didn’t realize how bad it is until (quite possibly) it is already too late.  We’re all in this together.  Since negative feedbacks can stabilize the system by bringing it back to its original state, we’ve got to do what we can, or risk losing it all.

Next time:  How bad might it get?