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CLIMATES OF THE PERIGLACIAL REGION IN THE LATE PLEISTOCENE AND EARLY HOLOCENE

CLIMATES OF THE PERIGLACIAL REGION IN THE LATE PLEISTOCENE AND EARLY HOLOCENE. R. A. Bryson and E. J. Hopkins Center for Climatic Research University of Wisconsin- Madison.

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CLIMATES OF THE PERIGLACIAL REGION IN THE LATE PLEISTOCENE AND EARLY HOLOCENE

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  1. CLIMATES OF THE PERIGLACIAL REGION IN THE LATE PLEISTOCENE AND EARLY HOLOCENE R. A. Bryson and E. J. Hopkins Center for Climatic Research University of Wisconsin- Madison

  2. WE WILL EXPLORE THE USE OF HIGH RESOLUTION PALAEOCLIMATIC MODELS TO LOOK FOR POTENTIAL LAKE TROUT REFUGIA DURING THE LATE PLEISTOCENE AND EARLY HOLOCENE • SALVELINUS NAMAYCUSH CAN DO VERY WELL IN SHALLOW COLD WATER. • HOW COLD? • WHERE WAS IT?

  3. REFUGIA, AT ANY TIME, HAD TO BE OUTSIDE THE GLACIAL BOUNDARY • EITHER DEEP COLD OR SHALLOW COLD WATER MUST BE FOUND

  4. COLD WATERS IN THE PAST • HOW COLD DOES THE WATER HAVE TO BE FOR A SHALLOW WATER LAKE TROUT HABITAT ? • MODERN CONDITIONS IN THE SOUTHERN TUNDRA SUPPORT SALMONIDS IN ABUNDANCE IN SHALLOW LAKES AND STREAMS.

  5. HOW COLD? • THE MAXIMUM TEMPERATURE IN THIS AREA MIGHT GIVE AN APPROXIMATE TEMPERATURE THRESHHOLD FOR SHALLOW WATER REFUGIA

  6. SURFACE WATERS IN SHALLOW LAKES AND STREAMS REACH MAXIMUM TEMPERATURES CLOSE TO AVERAGE AIR TEMPERATURE IN JULY 13-15° C. APPEARS TO BE APPROPRIATE AS A MAXIMUM TEMPERATURE

  7. FOR MODELING PAST CLIMATES WE WILL USE A MACROPHYSICAL HIGH RESOLUTION MODEL • THIS MODEL IS SITE-SPECIFIC SO THAT WE CAN IDENTIFY SMALL REGIONS SUCH AS A FRACTION OF A STATE OR FEW COUNTIES. • IT YIELDS 200 YEAR AVERAGE MONTHLY VALUES OF CLIMATIC VARIABLES. • IT RUNS ON A DESKTOP COMPUTER AND GIVES CORRECT MODERN VALUES. • BUT DOES IT WORK?

  8. COMPARISON OF PRECIPITATION RECONSTRUCTION FROM POLLEN DATA COMPARED TO THE MODEL FOR THE ISLE ROYALE REGION THE MODEL IS CORRECT FOR THE PRESENT

  9. TEMPERATURE IN THE ISLE ROYALE REGION FROM POLLEN AND FROM THE MODEL THE MODEL IS CORRECT FOR THE PRESENT

  10. THE SOUTHERN DRIFTLESS AREA WAS COLD ENOUGH IN THE LATE GLACIAL TIME

  11. BUT THERE WAS MUCH SNOW

  12. THE NORTHERN DRIFTLESS AREA WAS BETTER

  13. IT APPEARS THAT EVEN THE DRIFTLESS AREA WAS TOO WARM BY 15000 BP WAS DEEPER WATER AVAILABLE BY THEN?

  14. Glacial Lake WisconsinClayton and Attig (1989)

  15. The Region at 14,000 yr BP(from Illinois State Museum)

  16. The 15000-13000 BP Crunch • It appears that during this interval shallow waters may have been too warm for Lake Trout. • Somewhat deeper waters may have been cold enough due to much colder winters in this interval than at present. • Where were they at that time?

  17. Conclusion • We conclude that Salvelinus namaycush could have readily survived the Ice Age in cold surface waters, with no deep cold water available. • Modeling periglacial climates suggests that the best Late Glacial refugia may have been the Driftless Area. • It would appear that the transition to the Holocene may have been the most restricted habitat time.

  18. Contacts • Center for Climatic Research1225 W. Dayton St.Madison, WI 53706 • Reid A. Bryson rabryson@facstaff.wisc.edu • Edward J. Hopkins hopkins@meteor.wisc.edu

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