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.


==========================================================================
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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