>> what is the natural explanation that you are providing for the increase in global mean temperatures since industrialisation?

Since industrialization i.e. the 20th century? It's quite possible that there actually hasn't been any increase if you look at the original thermometer readings and take the trend over the period since the start of industrialization. That's why the record is full of cases where climatologists went back and revised old thermometer readings (by several degrees in some cases!), to make it seem like there has been. This shows up in old documents as references to various "pauses", "plateaus", "blips" and the "global cooling" period between 1945 and 1975 that can no longer be seen in current temperature databases.

Back in 1999 NASA was complaining that there'd been no warming in America in the 20th century:

https://web.archive.org/web/20090404150607/http://www.giss.n...

How can the absence of clear climate change in the United States be reconciled with continued reports of record global temperature? Part of the "answer" is that U.S. climate has been following a different course than global climate, at least so far. Figure 1 compares the temperature history in the U.S. and the world for the past 120 years. The U.S. has warmed during the past century, but the warming hardly exceeds year-to-year variability. Indeed, in the U.S. the warmest decade was the 1930s and the warmest year was 1934.

If you compare modern temperature graphs of the USA in the 20th century to the one they present there, you won't be able to understand what they're talking about because since then climatologists rewrote the temperature databases to create large amounts of 20th century warming in the USA. NASA has totally changed their claims about the past.

When they did that it was controversial. They justified it by saying the source data from the weather stations must be corrupted (because it didn't match their theory). A new weather station network was built in 2005 to address this concern. It also shows no warming since the day it opened. It's entirely possible the trend line for temperatures in the USA is zero since the start of industrialization.

What about elsewhere? Hard to say because long term data is sparse, often corrupted by urban development and also gets modified all the time. The NASA slider graph in your third link hides the fact that most of the temperature data they show for the globe over the 20th century is interpolated or modelled, not recorded with actual thermometers. Satellites? The show a bit of warming but also show long plateau periods where temperature doesn't move, and the data doesn't go back far enough to draw conclusions.

A trend line of zero since the start of industrialization doesn't mean temperatures don't sometimes go up. If you look at the 'real' data then you see a sine-wave like shape in the long term and a series of step changes in the short term, the so-called multidecadal oscillation and El Nino/La Nina factors. What causes it? Nobody really knows, maybe a combination of things, but there's no explanation for how human activity can cause this shape and plenty of evidence that climate has always been changing.