Samples of ancient carbon deposits from this era show a marked increase in concentrations of carbon - 12 relative to its heavier isotope carbon - 13, indicating a lot of lighter carbon might have been suddenly released at the time. (sciencemag.org)
Donald Grayson, an anthropologist at the University of Washington, worries that dates from the site might have been contaminated by ancient carbon from the huge aquifer that sits under much of Florida. (scientificamerican.com)
A University of Alaska Fairbanks - led research project has provided the first modern evidence of a landscape - level permafrost carbon feedback, in which thawing permafrost releases ancient carbon as climate - warming greenhouse gases. (sciencedaily.com)