Read here. Map source here. Scientists construct temperatures over the last 1,000 years from Scottish fjord sediment cores. The past temperatures of some 500 years ago reveal a rate of change warming and absolute temp levels that equal those of the late 20th century. Again, another peer-reviewed study confirms the natural state of constant temperature and climate change regardless of low/high CO2 atmospheric levels.
Summary: Today's temperatures are not unusual, nor unprecedented.
"The results of the two researchers' most recent efforts revealed that the most distinctive feature of the Loch Sunart temperature record was an abrupt warming at AD 1540 that led to a temperature anomaly of 1.1°C above the long-term mean from AD 1540-1600.....Noting that "the rate and magnitude of the inferred warming at AD 1540... is similar to the rate of change and magnitude observed during the late twentieth century," Cage and Austin concluded that "changes in twentieth century marine climate cannot yet be resolved from a background of natural variability over the last millennium," which is another way of saying that late 20th-century warming was not unusual enough to validly ascribe it to the concomitant increase in the air's CO2 content."
Additional climate history postings.