What was done
The authors reconstructed carbon storage in terrestrial vegetation of Northern Eurasia at four periods of time: the present, 5.5-6 thousand years ago (the Holocene Optimum, when mean global temperature was about 1 degree C warmer than present), 18-20 thousand years ago (the Last Glacial Maximum, when mean global temperature was between 3-4 degrees C cooler than present), and 125 thousand years ago (the Eemian Interglacial, when mean global temperature was about 2 degrees warmer than present).

What was learned
Vegetative carbon storage for the area studied was determined to be only 27% of current values during the last glacial maximum (66.1 Gt), 120% greater than present during the Holocene Optimum (292.1 Gt), and 155% greater than present during the previous interglacial (377.1 Gt).

What it means
These results clearly indicate that the plant life of Northern Eurasia is more productive and efficient in sequestering carbon at higher temperatures.  Indeed, it also shows that any future warming on the order of a couple of degrees would have a beneficial impact on the vegetation of this region.