"Surface" air temperature is the go to metric to illustrate "global" warming. Global "surface" air temperature is a combination of roughly 2 meter measured land temperature average measured at different elevations combined with sea "surface" temperature often measured a few meters below the surface. The data is what it is so we have to make the most of it, but it does lead to some real uncertainties that need to be addressed.
In the previous post I showed a few modeled "surface" air temperatures for the tropics (30S-30N) with SST. There is a pretty large spread. If you take a "historic" anomaly baseline, most of the model variance is in the future and if you take a future anomaly baseline most of the variance is in the past. Real temperatures don't change relationships with baseline choice.
ocean thermal basins as a reference, there is roughly a ten year lag between the southern hemisphere ocean and the northern Pacific, but without a longer instrumental time series you have to make a number of assumptions. I am not a big fan of lots of assumptions. Since there is evidence of lags in the various ocean basins which would start a fairly complex recovery oscillation, I would not jump on assigning blame for the 1900 to 1920 ocean cooling on the ~1880 volcanic event. Tambora or some other event could have started an oscillation where following events could hit in or out of phase making "forcing" appear less or more than it really should be. If you could find a definite signature of one event, you could use that initial condition to tease out ocean inertia influence on apparent "forcing".
2000 years of climate. According to that, circa 1700 AD is a reasonable starting point for the tropical ocean recovery. The event(s) that caused that dip in temperature may have starting in 1200 AD. There are potentially huge lags related to ocean heat content.
So even though this post is a bit of a rehash, I am posting it to try and get more folks involved in the pre-model and pre-Mann world of climate so perhaps something can actually move forward.