Data from: A millennium of climatic and floristic dynamics in the Eastern Cordillera of the Colombian Andes

The transition from the Medieval Climate Anomaly (MCA, 950-1250 CE) to the
Little Ice Age (LIA, 1350 to 1800 CE) is the largest pre-industrial
climate shift within the last two millennia, offering an opportunity to
study how vegetation responds to rapid climate change. We analyzed a
sedimentary record from the Colombian Andes to reconstruct regional
vegetation dynamics during this time interval, identify the modern
environmental distribution of taxa present in the fossil record, and
provide a reference for modern regional temperature change. A sediment
core was analyzed for organic geochemistry and pollen to reconstruct
environmental and vegetation variability between 800 and 1800 CE. Modern
occurrences of individuals of the genera found in the fossil record were
used to model the distribution of taxa across gradients of mean annual
temperature and precipitation. These models were used to reconstruct
temperature and precipitation across time and evaluate the probability of
occurrence of taxa from the fossil record across the contemporary
landscape.  Reconstructed regional vegetation dynamics
were highly coupled with global temperature patterns. Reconstructed
climate showed that conditions were warm and dry during the MCA, and cold
and relatively wet during the LIA, although quantitative estimations might
have been amplified by human disturbances. Rates of temperature change
during the MCA-LIA transition were substantially lower than those
calculated for the last two decades. Vegetation turnover between 800 and
1800 CE resembled those expressed through a transect extending ~30 km
southeast from the lake. Around lake Tota, modern rates of temperature
change have no precedent within the last two millennia. The modern
environmental affinities of taxa involved in vegetation turnover during
the MCA-LIA transition point to the importance of landscape diversity and
connectivity for rapid vegetation response to climate change.