On William Connolley's "Stoat" blog, Neven asked some questions. Responses are placed here (because William Connolley censors comments):
1) Sea Ice Extent in 2030, 2070 and 2100: My estimate for September/October arctic mininum sea ice is close to zero by 2030, and at zero in 2070 and 2100. My estimate for March/April maximum sea ice extent is 12 million square kilometers in 2030, 10 million square kilometers in 2070, and 8 million square kilometers in 2100.
2) Effects of Declining Sea Ice on the Jet Stream: Every single effect is obviously unknown, but I do not expect winters in the U.S. and Europe to become more severe (as some have speculated).
3) Sea Level Rise: As posted just awhile ago, I expect 0.14 meter of sea level rise by 2050, and 0.4 meters by 2100.
Postscript: Sea ice extent predictions can be compared with March/April average maximum values in the 2000s of a little over 14 million square kilometers, and 2000s average September/October minimum values of approximately 5.6 million square kilometers.