d13C and d18O time series with LIA, arid 4.2 Ka and cold 8.2 Ka events
marked by black stars.
Following Thatcher et al., 2020 both series depends on precipitation and
higher values refer to an arid climate, but we cannot forget that d18O may be
subject to a dominant impact due to annual mean temperature (Baker et al.,
2019). Also the 4.2 Ka event, at the Portugal latitude, probably took place 
in a warm (and arid) period, so the plots also show a relationship with
temperature. Based on that, as a general rule we can see a continuous warming
from 9-10 Ka (say from the end of Glacial Era) to ~3.2 Ka, followed by a
progressive temperature drop up to now (2103 CE) in the d18O series, while
the drop became , in d13C series, an almost constant value.
To be noted the (casual? Not so sure!) almost precise coincidence of the slope 
change (~3.2 Ka or ~1180 BCE) with the end of the Bronze Age and the beginning 
of the Iron Age.
Again based on a dependence of cave d18O from temperature, I note that after
3.2 Ka we face a general drop of the temperature, like the beginning of a
walk toward the next Glacial Era.