What is a feedback loop?
In my younger days, a common technique of musicians that didn't know how to play music would be to hold a guitar up to an amplifier and allow the noise coming from the guitar to go through the amplifier which would go through the guitar which would go through the amplifier until the system began an unearthly scream, which at the time was called music. I have no idea why.
Feedback loops have become a prominent feature of the melting of the polar ice cap: Melting causes dark water to be visible, which allows heat absorption, which causes more melting, which causes more water to be visible ... it's not a pretty scenario.
Neither is the feedback loop that's caused when permafrost melts and releases methane, which causes more warming, which causes more melting ... you get the idea.
A feedback loop in Greenland
Now comes word that a confluence of factors has apparently created a feedback loop that is accelerating the melting of the Greenland ice. The phenomenon is described in detail in this report from National Geographic.
This is a serious announcement, that will impact cities from Boston to Miami. The Greenland ice sheets have been calculated to contain enough ice, that if melted, would raise sea levels by 20 feet. So do yourself a favor. If you live along the Eastern Seaboard, go to your favorite information source and look up your elevation above sea level.
Almost time to panic
Melting rates have always been estimated conservatively, largely due to lack of information. Projections that were estimated to occur in 1000 years were then estimated to occur in 100 years, which were again estimated to occur in 30 years.
This was before the contribution of feedback loops was calculated.
So it brings up two choices that may not have been considered before: take up surfing; take up mountain climbing. Stay tuned, but DO understand that's it's the sea that will tell you what you need to do. Not scientists, and certainly not politicians.