"Splicing" (as with the temp hockey stick) is not valid science without showing natural variation in the older data (which you can't with ice cores since they average CO2 for a mininum of 30 years). The second problem is the Byrd station data is ludicrously cut off before it reached 285ppm +/- 10ppm about 10k years ago. Obviously a picture with an agenda.
Maybe so. But the key point I've made (numerous times) is that the maximum natural peak in atmospheric CO2 concentrations, over the past 640,000 years now with the EPICA core, is about 280 ppm (I'll accept +/- 10 ppm error). No matter how the core data is sliced/spliced/or diced, that is a salient fact. The more modern ice core data (Siple or Taylor or Law) starts there and then shows the increasing CO2 concentration commencing in the 1700s, and merging quite smoothly into the Mauna Loa measurements.
And it's not like we didn't know burning wood and kerosene and oil and gas would put CO2 into the atmosphere; so it shouldn't come as much of a surprise that atmospheric samples confirm that.