How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Alaskan Glaciers Advance and Retreat with Changes in Holocene Climate
Calkin, P.E., Wiles, G.C. and Barclay, D.J.  2001.  Holocene coastal glaciation of Alaska.  Quaternary Science Reviews 20: 449-461.

What was done
The authors reviewed "the most current and comprehensive research of Holocene glaciation" along the northernmost Gulf of Alaska between the Kenai Peninsula and Yakutat Bay.

What was learned
Several periods of glacial advance and retreat were noted during the past 7000 years.  Most recently, the authors note a general retreat during the Medieval Warm Period that lasted for "at least a few centuries prior to A.D. 1200."  Following this Medieval Climatic Optimum, there were three major intervals of Little Ice Age glacial advance: the early 15th century, the middle 17th century, and the last half of the 19th century.  During these latter time periods, glacier equilibrium line altitudes were depressed from 150 to 200 m below present values as Alaskan glaciers "reached their Holocene maximum extensions."

What it means
The existence of a Medieval Warm Period and a Little Ice Age in Alaska is obviously a reality.  What is more, it is interesting to note that glaciers there reached their maximum Holocene extensions during the Little Ice Age.  Hence, we can infer that Alaskan temperatures reached their Holocene minimum during this time as well.  Should it come as any surprise, therefore, if temperatures in Alaska rise significantly above the chill of the Little Ice Age in a natural recovery from the coldest period of the Holocene?