1. "Abrupt Climatic Changes and Events in the Cordilleran Holocene and Possible Cultural Implications" Reid A. Bryson and Alison Stenger Climate, People, and Environment Program Center for Climatic Research, University of Wisconsin – Madison

2. WHO CARES? Time is critical for cultural adaptation to climatic change. Adjustment to slow change is easy- to rapid change may be impossible or traumatic. The old idea of slow climatic change is no longer tenable.

3. 1. THERE MAY BE SHORT BUT INTENSE EVENTS OF GREAT HUMAN SIGNIFICANCE AND 2. SINCE CLIMATE SERIES ARE NON-STATIONARY, THE AVERAGE CLIMATE MAY CHANGE ABRUPTLY AND REMAIN CHANGED FOR MILLENNIA

4. 1. Tropical cyclones are very abrupt events and change rapidly in frequency They produce very heavy precipitation

5. Landslides and rivers of mud in the Nicaraguan Highlands What does this mean in The Rockies?

6. MOST “GULLY-WASHER” EVENTS IN THE INTERIOR ARE THE RESULT OF LEFTOVER REMNANTS OF TROPICAL STORMS OR DEPRESSIONS- EVEN IN HIGH LATITUDES AND THE WEST THE ORIGIN MAY BE OBSCURE SINCE THEY MAY ENTER THE WESTERLIES AND APPEAR AS ORDINARY, BUT VERY WET, WESTERLY STORMS

7. EXAMPLE IN PREHISTORY: FOUR TIMES AS MANY MID-HOLOCENE TROPICAL STORMS IN THE WESTERN PACIFIC. THESE RECURVE AND HEAD TOWARDS NORTH AMERICA

8. TROPICAL STORM REMNANTS REACHING THE COAST SHOW UP AS HIGH INTENSITY PRECIPITATION

9. 2. THE DYNAMICS OF THE ATMOSPHERE FORCES RAPID CLIMATIC CHANGES WHICH PRODUCE WHAT ARE CALLED NON-STATIONARY CLIMATIC SERIES. THIS MEANS THAT STANDARD STATISTICS DO NOT APPLY. CHANGES HAPPEN RAPIDLY, AND VARIABILITY CHANGES, AS DO EXTREMES.

10. WAVES IN THE WESTERLIES, THE NORTH- SOUTH MEANDERING SO OBVIOUS ALOFT, MUST OCCUR IN WHOLE NUMBERS AROUND THE HEMISPHERE- 3 OR 4 OR 5 ETC., BUT NEVER FRACTONS LIKE 3.27. THUS AS CONDITIONS CHANGE, THE NUMBER MUST CHANGE ABRUPTLY BY A WHOLE STEP. THIS CHANGES THE PATTERN OF THE WHOLE HEMISPHERE AT THE SAME TIME.

11. CHANGE OF WAVE NUMBER IN THE WESTERLIES MAY MAKE LITTLE CHANGE OVER CREST, BUT OPPOSITE CHANGE ON FLANKS

12. THE CORDILLERA ITSELF FORCES CONTRASTS DRY WET DRY RIDGE NORTH OF THE JETSTREAM, TROUGH SOUTH OF THE JETSTREAM. THE ROUGHNESS OF THE MOUNTAINS FORCES A RAINFALL PATTERN

13. A SMALL SHIFT IN THE MEAN LATITUDE OF THE JET MAY CHANGE THE ROCKIES CLIMATE DRAMATICALLY AND FAST

14. THE DIVISIONS OF THE HOLOCENE WERE SHARPLY DEFINED- AS WERE THE CORRESPONDING CULTURAL STAGES

15. WITH HIGH RESOLUTION SAMPLING THE RAPIDITY OF CHANGE MAY BE OBVIOUS AS COMPARED HERE AGAINST A MODEL

16. SMALL CHANGES IN THE AVERAGE MEANS DRAMATIC CHANGES IN THE EXTREMES

17. SUMMARY 1.CLIMATE IS MORE THAN WET/DRY, WARM/COLD. THERE ARE IMPORTANT SHORT EVENTS LIKE TYPHOONS AND FLASH FLOODS. 2.CLIMATE NORMALLY CHANGES RAPIDLY. 3. THESE CHANGES WILL BE MISSED WITHOUT CLOSE SAMPLING i.e. 100 YEAR RESOLUTION OR LESS.