The positive gain from albedo feedback has been well-known for quite some time. Its part of why the Arctic is heating up so much faster than the rest of the wo

The positive gain from albedo feedback has been well-known for quite some time. Its part of why the Arctic is heating up so much faster than the rest of the world right now. The negative gain from weathering and volcanism is also quite well-known. The authors of this paper put 2 and 2 together and showed that you only need a brief period of reduced insolation to trigger a snowball earth, and that once insolation returns to normal it can stay in the snowball state for much longer.