[neverdem]

That's a ridiculous statement. Even reading the abstract indicates it's only about the factor which caused a change in the timing of glacial/interglacial periods. For that particular aspect of paleoclimate, CO2 is now shown not to be the causative factor. This paper has nothing else to do with CO2 as a climate change driver, which primarily means a determinant of global temperature and changes in global temperature. You'll note that they even say in the abstract: "These estimates are consistent with a close linkage between atmospheric CO2 concentration and global climate,"

How does that statement "undermine carbon dioxide as a driving factor causing climate change"?

Atmospheric Carbon Dioxide Concentration Across the Mid-Pleistocene Transition

The dominant period of Pleistocene glacial cycles changed during the mid-Pleistocene from 40,000 years to 100,000 years, for as yet unknown reasons. Here we present a 2.1-million-year record of sea surface partial pressure of CO2 (PCO2), based on boron isotopes in planktic foraminifer shells, which suggests that the atmospheric partial pressure of CO2 (pCO2) was relatively stable before the mid-Pleistocene climate transition. Glacial PCO2 was ~31 microatmospheres higher before the transition (more than 1 million years ago), but interglacial PCO2 was similar to that of late Pleistocene interglacial cycles (<450,000 years ago). These estimates are consistent with a close linkage between atmospheric CO2 concentration and global climate, but the lack of a gradual decrease in interglacial PCO2 does not support the suggestion that a long-term drawdown of atmospheric CO2 was the main cause of the climate transition.

It's right there in the abstract.

Ice cores from Antarctica show that at the end of recent ice ages, the concentration of carbon dioxide in the atmosphere usually started to rise only after temperatures had begun to climb. There is uncertainty about the timings, partly because the air trapped in the cores is younger than the ice, but it appears the lags might sometimes have been 800 years or more.

If carbon dioxide positively forced towards warmer temperature we wouldn't need to worry about ice ages again. It's been much greater that 10 times the current concentration of CO2.

[cogitator]

does not support the suggestion that a long-term drawdown of atmospheric CO2 was the main cause of the climate transition.

It's about the cause of the climate transition (altered glacial/interglacial timing). It's not about the effect of CO2 on global temperatures.

If carbon dioxide positively forced towards warmer temperature we wouldn't need to worry about ice ages again.

We sure don't. Read my profile, point #5.

or this

The Start and End of our Interglacial (PDF of a slide presentation)