GEOG5426 Megadrought II

MEDIEVAL WARM PERIOD

Professor Hubert H. Lamb University of East Anglia

Climate Research Unit University of East Anglia

And multifarious evidence of a meterological nature from historical records in various parts of the world from the Arctic to New Zealand... has been found to suggest a warmer epoch lasting several centuries between about A.D. 900 or 1000 and about 1200 or 1200.”

“

Lamb 1965. The early medieval warm epoch and its sequel.

Mildness or severity of winter weather

Raininess or drought in July and August

Winter severity index

High summer wetness index

DJF temperature (°C)

JA precipitation (% of average)

Temperatures prevailing in central England, 50-year averages Lamb, 1965

Summer temperatures prevailing in central England, 50-year averages Lamb, 1965

A prevailing warm epoch with dry anticyclonic character, especially in summer, in temperate Europe between about 1000 and 1300 A.D. appears to be confirmed.”

“

Lamb 1965. The early medieval warm epoch and its sequel.

Intergovernmental Panel on Climate ChangeClimate Change: The IPCC Scientific Assessment1990

Schematic diagram of global temperature variations since the last thousand years. IPCC 1990

The do!ed line nominally represents conditions near the beginning of the twentieth century.”

“

Schematic diagram of global temperature variations since the last thousand years. IPCC 1990

Chapter 7. Observed Climate Variation and Change. IPCC 1990.

The late tenth to early thirteenth centuries (about AD 950-125) appear to have been exceptionally warm in western Europe, Iceland and Greenland (Alexandre 1987, Lamb 1988). This period is known as the Medieval Climatic Optimum. China was, however, cold at this time (mainly in winter) but South Japan was warm (Yoshino, 1978).”

“

The problem is confounded by numerous studies that have used the term “Medieval Warm Period” for any climatic anomaly that occurred at some time in the historical Medieval period (500 to 1500 A.D.)—even if the record is unrelated to temperature.

Bradley et al, 2003, Science

“

The warmest 30-year periods prior to AD 1970. Bradley et al., 2003

The balance of evidence does not point to a High Medieval period that was as warm as or warmer than the late 20th century. However, more climate records are required to explain the likely causes for climate variations over the last millennium and to fully understand natural climate variability, which will certainly accompany future anthropogenic effects on climate.

Bradley et al, 2003, Science

“

Goosse et al., 2006

solar irradiance

volcanic forcing

CO2 concentration

forest cover

aerosol load

Goosse et al., 2006

Solar irradiance

Goosse et al., 2006

Volcanic forcing

Goosse et al., 2006

CO2 concentration

Goosse et al., 2006

The term “Medieval Warm Period”, of limited meaning at hemispheric scale, nonetheless thus appears reasonable as applied specifically to summer European temperatures, the region the term was originally applied to.”

“

Goosse 2006. The origin of the European “Medieval Warm Period”.

By November 3

[Tentative] list of 10 articles related to your region and time period.