The same can not be said of decadal scale temperature spikes on Earth. (tamino.wordpress.com)
We document a deeper aragonite saturation horizon and higher near surface aragonite saturation state in the summers of 2014 and 2015 (compared with 2010 — 2013), associated with anomalous warm conditions and decadal scale oscillations. (news-oceanacidification-icc.org)
It doesn't seem surprising to me that GCM simulations don't give useful decadal predictions on regional scale (or at least they are just beginning to get to the point where decadal scale predictions have useful skill IIRC). (realclimate.org)