MSGID: 1:317/3 63fd836f   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Climate trends in the west, today and 11,000 years ago    
    What we think of as the west coast's climate is 'only' a few thousand   
   years old    
      
     Date:   
         February 27, 2023   
     Source:   
         University of California - Davis   
     Summary:   
         What we think of as the classic West Coast climate began just   
         about 4,000 years ago, finds a study on climate trends of the   
         Holocene era.   
      
      
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   FULL STORY   
   ==========================================================================   
   People often say things like Phoenix has always been dry; Seattle has   
   always been wet; and San Francisco has always been foggy. But "always"   
   is a strong word.   
      
      
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   A study from the University of California, Davis, synthesizes climate   
   trends across the Western U.S. during a relatively young period of   
   Earth's history - - the Holocene Era, which stretches from the present   
   day to the past 11,000 years. This look at the reallyOld West shows that   
   the hallmarks of California's climate -- the foggy coastlines that gave   
   rise to towering redwoods, the ocean upwelling that spawned productive   
   fisheries, the warm summers and mild winters -- began around 4,000   
   years ago.   
      
   It also reveals a time when the Pacific Northwest was warm and dry and   
   the Southwest was warm and wet.   
      
   An understudied era: The current one Published in Climate of the Past, a   
   journal of the European Geosciences Union, the study provides a baseline   
   against which modern climate change in the region can be considered. It   
   also sheds light on a lesser-studied geological epoch - - the current one,   
   the Holocene.   
      
   "We kept looking for this paper, and it didn't exist," said lead author   
   Hannah Palmer, who recently earned her Ph.D. from the UC Davis Department   
   of Earth and Planetary Sciences. "There are many records of past climate   
   for a single location, but no one had put it all together to understand   
   the big picture. So we decided to write it."  The authors analyzed more   
   than 40 published studies, examining the interplay among land and sea   
   temperature, hydroclimate and fire activity across three distinct phases.   
      
   The study found:   
       * Compared to pre-Holocene conditions (the last Glacial period),   
       the Early   
         Holocene (11,700-8,200 years ago) was a time of warm seas, a warm   
         and dry Pacific Northwest, a warm and wet Southwest and fairly   
         low fire activity.   
      
       * By the Middle Holocene (8,200-4,200 years ago), that pattern   
       reversed:   
         The ocean's surface cooled, the Pacific Northwest became cool and   
         wet, and the Southwest became drier.   
      
       * The Late Holocene (4,200 years ago-present) is the most climatically   
         variable period. It marks a period when the "modern" climate and   
         temperature patterns are established. The study noted a defined   
         interval of fire activity over the past two centuries that is   
         linked to human activity.   
      
   Unprecedented interval The study also considered the impact of humans on   
   environmental changes at the time, noting that the Era of Colonization   
   (1850-present) represents an unprecedented environmental interval in   
   the climate records.   
      
   "Humans have been living here throughout the entire Holocene," Palmer   
   said.   
      
   "The climate impacted them, and they impacted the climate, especially in   
   recent centuries. This paper shows how that push and pull has changed   
   over the past 11,000 years."  Different responses "Sometimes people   
   point to recent rain or cold snaps as evidence against climate change,"   
   said co-author Veronica Padilla Vriesman, a recent Ph.D.   
      
   graduate from UC Davis Department of Earth and Planetary Sciences. "This   
   study illustrates how different regions respond differently to global   
   climate changes. That long-term perspective helps us understand the   
   historical climate of the western U.S. and how it may respond moving   
   forward."  The study stemmed from a graduate seminar about the Holocene   
   period led by Tessa Hill, a professor in the Department of Earth and   
   Planetary Sciences and associate vice provost of Public Scholarship and   
   Engagement. Additional co- authors include Caitlin Livsey and Carina   
   Fish. All authors were part of Hill's Ocean Climate Lab at the UC   
   Davis Bodega Marine Laboratory in the Department of Earth and Planetary   
   Sciences.   
      
   "Climate records from the Holocene provide a valuable window into the   
   context of human-caused climate change," said Hill. "They provide an   
   opportunity for us to understand places that may be more or less resilient   
   to change in the future."  The study was funded by the National Science   
   Foundation.   
      
       * RELATED_TOPICS   
             o Earth_&_Climate   
                   # Climate # Environmental_Awareness # Global_Warming #   
                   Environmental_Issues   
             o Fossils_&_Ruins   
                   # Early_Climate # Fossils # Origin_of_Life # Early_Mammals   
       * RELATED_TERMS   
             o Neandertal_interaction_with_Cro-Magnons o Climate_model o   
             Temperature_record_of_the_past_1000_years o Gulf_Stream   
             o Recent_single-origin_hypothesis o Cenozoic o   
             Global_warming_controversy o Paleoclimatology   
      
   ==========================================================================   
   Story Source: Materials provided by   
   University_of_California_-_Davis. Original written by Kat Kerlin. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Hannah M. Palmer, Veronica Padilla Vriesman, Caitlin M. Livsey,   
      Carina R.   
      
         Fish, Tessa M. Hill. Holocene climate and oceanography of the   
         coastal Western United States and California Current System. Climate   
         of the Past, 2023; 19 (1): 199 DOI: 10.5194/cp-19-199-2023   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230227161425.htm   
      
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