Figure 4. The North Atlantic Ocean distribution of the planktonic foraminifera N. pachyderma (sin) at the Last Glacial Maximum (LGM). Compared to the modern distribution (dashed line near Greenland ) this "foram" found a much wider geographic range at the LGM. This data set shows that the polar front moved very far to the south and traveled more zonally across the LGM Atlantic. It is an excellent example of how marine populations can "feel" climate change.
Image courtesy of Jess Adkins, California Institute of Technology, as modified from McIntyre et al. (1976) Glacial North Atlantic 18,0000 years ago: A CLIMAP reconstruction. GSA Memoir 145, 43-75.