What's the source of the temperature data in that graph?
The Friis-Christensen, E., and K. Lassen study uses average Northern Hemphisphere surface temperatures.
The webpage containing the graph is: http://web.dmi.dk/solar-terrestrial/space_weather/
it doesn't show the warming since the mid-1800s (which is 0.6-0.8 C in the surface instrumental record)?
You can always look at link I provided above to Muller's History of Climate introduction, which presents the full range of data he used right up to 1999 or thereabouts.
Beginning in the early 1900s, the climate of the world began to warm. This is evident in Figure 1-1, which shows the average Earth surface temperature from 1880 through 1999. The temperature is an area-weighted average over the land and ocean compiled by the National Oceanographic and Atmospheric Administration, using an averaging technique devised by Quayle et al. ; see also . In the plot, "zero" temperature is defined as the temperature in 1950. The fine line shows the monthly temperatures; the thicker line shows the 12 month yearly averages.
But in the modern timeframe, the Antarctic is partially decoupled from processes happening in the rest of the world.
Actually I was wrong on the 2400 year data set, I didn't look to verify and assumed Vostok Data, after checking Muller's introduction, the actual data set used was
Data from a kilometer long core taken from the Greenland glacier, as part of the Greenland Ice Sheet Project "GISP2" , are shown in Figure 1-2. For comparison purposes, the zero of temperature scale for this plot was set to match that of the previous plot. For historical interest, we marked some events from European history.
