If you take the "standard" volcanic forcing estimates and try to isolate the impact of volcanoes on climate you will find that things just don't add up. That is because the concept of a "standard" forcing is flawed. Without going into a great deal of math, try to clear you mind and think of what you have sans all the theories.
You have a ocean with a sea surface temperature that is always greater than the average temperature of the oceans. You have an average temperature of the oceans which is about equal to the land surface temperature. You have a northern hemisphere which is about 3 degrees warmer than the southern hemisphere. If you change how well the sea surface temperature mixes with the deeper oceans or divides itself between the hemispheres you will change the "average" surface temperature. There is no "forcing" required in the radiant physics sense, just changes in the mechanical mixing efficiency. A small imbalance in "forcing" can have a greater impact than a larger "global" "forcing" change. It doesn't matter if that forcing is positive, negative, due to volcanoes, the sun or unicorns, imbalances will always have a greater impact on shorter time scales than uniform forcing.
Why? Because a "uniform" forcing reduces the potential of imbalances, decreasing the mixing efficiency actually slowing the rate of warming. Since the Earth land and oceans are not symmetrically distributed around either the equatorial or polar planes, there will always be some imbalances and temperature gradients, uniform forcing just serves to reduce the degree of imbalance.
My writing a guest post on "Volcanic Direct and Indirect Effects on Climate" would be a complete waste of time because the chosen radiant frame of reference doesn't allow the communication of the basics completely ignored by radiant physics based climate theory. For "global" warming in the radiant sense everything "globally" would warm at the same rate, slow as molasses. One full overturning of the oceans takes on the order of 1700 years. It would take an "average", based on the limited data available, of ~316 years for the "globe" to warm 0.8C. By using land based and surface skin measurements warming can "appear" to be greater, but once you back out the internal pseudo-oscillations, about 316 years per 0.8 C degrees.
This chart shows the combined volcanic and solar impact on degree latitude bands of the oceans using the ERSSTv3b data downloaded from KNMI Climate Explorer. You can see the complex recovery paths of each band with the Northern Hemisphere having the fastest recovery producing an overshot of the mean and the combined oceans regions "hunting" for a new "equilibrium" or quasi-steady state condition. The only spot the bands are even close to being in synch is during the 1910 period. The most interesting of all the bands is the 65S to 55S band which has the highest mixing efficiency. The strongest responses are related to the lowest mixing efficiencies with 35N-45N and 45N-55N located at ocean heat transfer choke points being the strongest. That choke point causes the land surfaces in that region to amplify the impact of the reduced mixing efficiency resulting in land temperatures being amplified by ~1.8 times the SST change. Some portion of that amplification is likely due to "other" causes, but without the choke point, land warming would be more uniform.
The impact of the change in mixing efficiency has been highlighted in a number of papers focusing on climate of the past. In their paper, On the Relative Importance of Meridional and Zonal Sea Surface Temperature Gradients for the onset of of Ice Ages and on Pleocene-Pleistocene Climate Evolution, Brierley and Fedorov estimate impacts of 3.2 C and 0.6C for respective impacts. It is not like the information is not out there, it is that the radiant "uniform" forcing models are in conflict with the reality.
To "explain" how imbalanced forcing can both warm or cool depending on region and timing requires a audience capable of listening, not an audience wedded to a failing theory.
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