An Overview of Studies on Medieval Warm Period

The Medieval Warm Period is a crucial epoch during last two millennia.In this review a number of lines of evidence are considered in order to evaluate whether this warm event was regional or global,whether it was uniform climatically or synchronized,how warm was the period,precipitation variation and what caused this climate event.Based on large number of research,we hold that this epoch was most likely global rather than regional though we have only a sparse picture of this epoch.The balance of evidence may do point that the period was not warmer than 20th century.Besides,all reconstruction supports an unsustained Medieval warm period.As mentioned precipitation variation,different areas have different wet or dry condition.Precipitation and temperature do have distinct physical characteristics responded the natural forcing.In the end,many reconstructions and simulations indicate that natural factor,such as solar radiation and volcanism can explain most of climatic changes observed during this episode,however the interaction of climatic system can not be ignored.Consequently,it is very important to joint the effect of external and internal factors in decoding the mechanism of climate change.We hope that the following works could be paid more attention: updating old and developing new proxy data,promoting the ways of reconstruction and keeping a scientific attitude toward next research.