The warm period became known as the Medieval Warm Period, and the cold period was called the
Little Ice Age (LIA). However, that view was questioned by other researchers; the
IPCC First Assessment Report of 1990 discussed the "Medieval Warm Period around 1000 AD (which may not have been global) and the Little Ice Age which ended only in the middle to late nineteenth century." It said temperatures in the "late tenth to early thirteenth centuries (about AD 950-1250) appear to have been exceptionally warm in western Europe, Iceland and Greenland".
[12] The
IPCC Third Assessment Report from 2001 summarized newer research: "
evidence does not support globally synchronous periods of anomalous cold or warmth over this time frame, and the conventional terms of 'Little Ice Age' and 'Medieval Warm Period' appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries."[13] Global temperature records taken from ice cores, tree rings, and lake deposits, have shown that the Earth may have been slightly cooler globally (by 0.03 °C) than in the early and mid-20th century.[14][15]