Closer to home: Climate variability in the past 1000 years

As this blog enters into its final third, I will be leaving past records to focus on Northern Hemisphere climate variability over the past 1000 years. These considerably differ from the 8200 yr and Younger Dryas events since there is no dammed freshwater Lake Agassiz to cause freshwater outbursts. Therefore, it will be interesting to see the mechanisms causing abrupt climate shifts in this time period.


This post will serve as an introduction to the past 1000 years' climate. Temperature data can be seen in a 2004 paper by Keller (1). He compiles model results from 7 model runs showing temperature anomalies compared with the observed 1961-1990 average, shown in Fig 1. This graph helps to identify three established key periods within the record, the Medieval Warm Period (MWP) from 800-1200 AD, the Little Ice Age (LIA) from 1200-1800 AD and the recent anthropogenic forced warming since 1850. 

Fig. 1 Graph showing temperature variability in past 1200 years (Keller, 2004)

These three events will be discussed separately with a final post relating to the possible future of abrupt climate change. 


(1) Keller (2004) doi:10.1016/j.asr.2004.01.020