… This chart is interesting not just for the periods of warmth but for the incidents of cold. The 8000 years ago event sticks out like a sore thumb (6200BC) and likewise an event just before 5000 years ago and around 4300 years ago. In contrast, we don't have a cold blip at 1200 or 1000BC to qualify as the end of Late Bronze Age event. Instead, it is very warm. Why would that be? Was something different going on? One explanation might be that as it covers such a long period of time it is not time perfect – and requires some adjustments. That seems like picking at straws. The 1159-41BC low growth tree ring event should show itself up in such a chart (although it did not measure in hundreds of years like the 8000, 5000, and 4300 years ago events. It was a blip – and may have been volcanic. There could be a small blip there (in the chart) – but temperatures did not plunge as dramatically as earlier events if that is so.