There’s a wonderful point where a lot of ‘scut work’ is done and you can start to just cook through things. Code built and pretty much tested (still needs a rigorous ‘last fine comb’ just to be sure) but simple changes make more variations very quickly. That’s where I am now.

So I’ve just pumped out two new graphs. One for the Northern Hemisphere and one for the Southern Hemisphere. S.H. is very flat. Not much you can do with a load of ocean and coastline. N.H. is where the action comes from. I had to rescale the S.H. graph to match the north in scale, but that makes it a bit hard to see much change. Then again, that’s sort of the point.

Click on the S.H. graph and then expand it to full size. Notice that many times in history the temperature are at about the same point…