This chart by the Berkeley Earth Surface Temperature project is part of their summary of findings under the heading, Human Effect. That makes this chart wrong and misleading. The chart starts in 1750 when there is huge uncertainty shown is gray scale and 1700 to 1817 was pretty much the depths of the colder or at least cooler than normal Little Ice Age. Various estimates put the Little Ice Age "global" temperature depression in the 0.9 C range and the duration of the LIA in the 150 to 300 year range. During that time there would have been a negative ocean energy imbalance meaning the Oceans were losing more energy than than they gained which would require a similar or longer period for the oceans to regain that lost energy. The chart makes no attempt to determine how much impact that recovery had on "global" land surface temperature but still tacks on the "Human Effect" label like they had some magical insight.
In one of my post called "Is a Picture worth a Trillion Dollars" I used a Indo-Pacific Warm Pool Sea Surface Temperature (SST) reconstruction by Oppo (2009) with a reconstruction of CO2 to estimate what range of "sensitivity" climate may have to CO2 forcing. That is just using CO2 as a reference for all atmospheric forcing including water vapor. If surface temperature increased by 1.5C given the less than stellar performing estimates of "sensitivity" 2/3 or 1C of that increase should have been due to water vapor response and if there was 0.9 C of recovery, most of the warming amplification would have to be due to albedo change and increased water vapor. You can't have scary feedbacks only when you want them.
This chart shows the estimates with 0.8C being the better match to pre-LIA conditions, 1.6C being possible and 3C being just about impossible as far as CO2 forcing goes. That is not enough for most folks that have been indoctrinated by the arm waving alarmist Climate Scientists that seem to be hell bent on making fools of themselves by over confidently thinking they have this sucker figured out.
This series on Fun with Forcing is not geared to the CO2 equivalent and Volcanic forcing impacts as much as using them for references to tease out solar and some of the other impacts.
Solar forcing is like the red haired step child of climate science. It is complicated as all git out because the globe has asymmetrical surface thermodynamics, huge seasonal swings in solar forcing by latitude and unpredictable ocean and atmospheric heat transport. That is why climate science needs models that work and work extremely well. This chart is a rough fit for Multi-layer Solar forcing. Solar is absorbed by the atmosphere, the bulk sea surface layer (0-30 meters roughly) and the deeper ocean mixing layer (30 to 1000 meters) which all have different time delays (lags) and heat transport mechanisms. The North Atlantic is warmer than the ocean average by about 3C, the northern Pacific varies more than the ocean average and the southern oceans are just about rock solid stable, which combine to create various ocean oscillations with periods greater than 60 years. With only a 160 years or so of ocean temperature data and that not all that accurate, you can get lost pretty quick trying to follow the energy. Here I am only attempting lags of up to 8 years.
This attempt has a surface lag of zero for the ocean/atmosphere boundary layer, 27 months for the bulk surface layer and 94 months for the deep ocean 0-1000 meter layer. The correlation between this forcing estimate and the HadSST3 data is 90% which is not great but about as good as can be expected with margin of error of the HADSST3 data. Note that the CO2 and Volcanic forcing using the BEST data (CO2 was extended using the Mauna Loa data) is based on a CO2 "sensitivity" of 1C per doubling (3.7Wm-2) using 275 ppm as "normal" CO2, the Volcanic data was massaged a bit more with a 2 year trailing average to produce a shark's tooth response instead of a spike and divide by 48 to scale to temperature.
This chart attempts to show how the multi-layer works. You have a small impact due to the zero lag portion which amounts to about 0.15C with a short duration. About 0.18C with a 27 month average lag for the bulk layer. These two combine for about 0.2 C impact on average. The 94 month lag is a bit more tricky because it can be in phase or out of phase with the other two producing a frustrating pseudo-cyclic behavior. Based on this combination, the solar impact maximum range is about 0.4C for the 1850 to present period. That is about half of the ocean warming. Since 1950 the solar and other forcing are so intertwined that it may not be possible to separate one from the other, but over the full period, solar appears to have about twice the originally estimated impact most of which is likely due to water vapor/ cloud cover enhancing surface energy retention. These are just estimates and correlation does not prove causation, but circumstantial evidence is definitely beginning to pile on.
I am sure the minions of the Great and Powerful Carbon will find great fault with my crude methods, but there is little more than wiggle matching that can be done until a solid "normal" reference is determined.
Just thought I would toss that out there.
Update for Andy Lacis,