New study reveals abrupt shift in tropical Pacific climate during Little
Ice Age
The shift to an El Nin~o-like phase between 1600 and 1900 A.D. was
identified by sediment analysis of a Philippine lake

Date:
July 3, 2023
Source:
GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre
Summary:
An El Nin~o event has officially begun. The climate phenomenon,
which originates in the tropical Pacific and occurs in intervals of
a few years will shape weather across the planet for the next year
or more and give rise to various climatic extremes. El Nin~o-like
conditions can also occur on longer time scales of decades or
centuries. This has been shown to have occurred in the recent past.


Facebook Twitter Pinterest LinkedIN Email

==========================================================================
FULL STORY ==========================================================================
An El Nin~o event has officially begun. The climate phenomenon, which originates in the tropical Pacific and occurs in intervals of a few years
will shape weather across the planet for the next year or more and give
rise to various climatic extremes. El Nin~o-like conditions can also occur
on longer time scales of decades or centuries. This has been shown to have occurred in the recent past by an international research team led by Ana Prohaska of the University of Copenhagen and Dirk Sachse of the German
Research Centre for Geosciences (GFZ). Their analysis of biomarkers --
organic molecules or molecular fossils from vascular plants -- in the
sediments of a lake in the Philippines indicates an unusually dry phase
in the region during the Little Ice Age between 1600 and 1900 A.D. The
results have now been published in the journal Communications Earth and Environment. They show how important the understanding of past dynamics
of the tropical Pacific ocean-atmosphere climate is for the improvement
of climate models and the prediction of future climate changes.

Background: The El Nin~o phenomenon A striking feature of climate in the equatorial Pacific is its east-west asymmetry, with warmer surface waters
in the west and colder surface waters in the east. Easterly winds drive
surface water westwards, allowing equatorial upwelling to bring cooler
water to the eastern side. This asymmetry breaks down in today's climate, leading to El Nin~o conditions that occur at irregular intervals of a
few years and last for 9-12 months.

During an El Nin~o event, sea surface temperatures along the equator
increase from the Peruvian coast to the central Pacific. The southeast
trade wind weakens considerably, and light westerly winds may develop. In
the western equatorial Pacific, which is otherwise characterised by
abundant precipitation, an exceptional dryness takes hold, whereas the otherwise dry eastern edges of the Pacific may experience heavy rainfall.

Against the backdrop of global warming, El Nin~o is expected to bring
record- breaking high temperatures and various extreme climate events
globally such as droughts, floods and wildfires, which will significantly affect the lives and well-being of millions of people.

El Nin~o-like phenomena on longer time scales While El Nin~o is an
interannual climate phenomenon, the climate system of the tropical
Pacific can also exhibit El Nin~o-like behaviour on longer time scales
of decades and centuries, which is linked to the east-west gradient of
sea surface temperatures in the Pacific. Such behaviour has been shown
to have transpired in the recent past by a team led by Ana Prohaska,
assistant professor at the University of Copenhagen and formerly a
visiting scientist at the GFZ, and Dirk Sachse, working group leader in
GFZ Section 4.6 "Geomorphology" and director of Topic 5 "Landscapes of the Future" of the Helmholtz research programme "Changing Earth -- Sustaining
our Future," in the journal Communications Earth and Environment.

They describe such a pronounced shift to El Nin~o-like conditions in
the second half of the Little Ice Age, lasting from about 1630 to 1900
A.D. What is particularly remarkable is the short period of only one
generation within which conditions changed for a period of more than
200 years.

Climate insights into the past through studies of sediment cores The
research team examined sediment cores from Lake Bulusan in the northern Philippines, which were collected in 2013. The sediment sequence provides insights into the climatic evolution of the past 1,400 years in a region
that is today strongly affected by El Nin~o events. In particular,
the researchers analysed the composition of stable hydrogen isotopes in
leaf wax biomarkers (dDwax). These are molecular fossils that originate
from the protective surface layer of leaves from vascular plants. The
analysis provides insights into water supply during their lifetime.

Drier conditions in the western Pacific during the Little Ice Age The
study shows a sudden and significant increase in dDwax values between
1600 and 1650 A.D., indicating a shift towards drier conditions in
the western tropical Pacific during the second half of the Little Ice
Age. The researchers attribute this change to a shift in the mean state
of the tropical Pacific Ocean related to zonal gradients, i.e., east-west differences in sea surface temperature.

The significance of the current study for climate predictions Ana
Prohaska, lead author of the study, emphasises the importance of this
research: "Our study provides compelling evidence for the intricate relationship between zonal gradients in sea surface temperature and hydrological patterns in the tropical Pacific. Understanding the nature
and pace of past changes in the tropical Pacific climate system is
critical for predicting future climate change and its potential impact
on this vulnerable region." Dirk Sachse from the GFZ adds: "Although
there is increasing evidence that sudden climatic changes have occurred
in the past, current climate models cannot reproduce such abrupt shifts
in the mean state in the tropical Pacific.

This highlights that the understanding of the underlying mechanisms is
still limited. In the context of anthropogenic climate change, a better understanding of the drivers and consequences of the complex dynamics of
the mean state of the tropical Pacific is of great importance. For this,
the integration of palaeoclimatological data into modern climate models
plays a crucial role."
* RELATED_TOPICS
o Earth_&_Climate
# Climate # Global_Warming # Environmental_Awareness
# Weather
o Fossils_&_Ruins
# Early_Climate # Evolution # Ancient_DNA # Fossils
* RELATED_TERMS
o El_Nin~o-Southern_Oscillation o Weather o Season o
Greenland_ice_sheet o Temperature_record_of_the_past_1000_years
o Climate o National_Hurricane_Center o Bushfire

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

Print

Email

Share ========================================================================== ****** 1 ****** ***** 2 ***** **** 3 ****
*** 4 *** ** 5 ** Breaking this hour ==========================================================================
* Screens_More_Versatile_Than_LED:_Fins_and_...

* GM_Pig_Heart_in_a_Human_Patient:_Update *
Multiple_Sclerosis_Severity * Wind_Farm_Noise_and_Road_Traffic_Noise
* Mavericks_and_Horizontal_Gene_Transfer *
Early_Reading_for_Pleasure:_Brains,_...

* New_Light_Shed_On_Evolution_of_Animals *
Gullies_On_Mars_from_Liquid_Meltwater?
* DNA_Organization_in_Real-Time *
How_the_Cat_Nose_Knows_What_It's_Smelling

Trending Topics this week ========================================================================== PLANTS_&_ANIMALS Birds Animal_Learning_and_Intelligence Molecular_Biology EARTH_&_CLIMATE Water Weather Climate FOSSILS_&_RUINS Dinosaurs
Early_Mammals Origin_of_Life


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

Strange & Offbeat ========================================================================== PLANTS_&_ANIMALS Squash_Bugs_Are_Attracted_to_and_Eat_Each_Other's_Poop_to_Stock_Their Microbiome How_Urea_May_Have_Been_the_Gateway_to_Life Octopus_Sleep_Is_Surprisingly_Similar_to_Humans_and_Contains_a_Wake-Like_Stage EARTH_&_CLIMATE
Turning_Old_Maps_Into_3D_Digital_Models_of_Lost_Neighborhoods Orangutans_Can_Make_Two_Sounds_at_the_Same_Time,_Similar_to_Human_Beatboxing, Study_Finds Do_Hummingbirds_Drink_Alcohol?_More_Often_Than_You_Think FOSSILS_&_RUINS Newly_Discovered_Jurassic_Fossils_in_Texas Megalodon_Was_No_Cold-Blooded_Killer 'We're_All_Asgardians':_New_Clues_About_the_Origin_of_Complex_Life
Story Source: Materials provided by GFZ_GeoForschungsZentrum_Potsdam,_Helmholtz_Centre. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Ana Prohaska, Alistair W. R. Seddon, Bernd Meese, Katherine
J. Willis,
John C. H. Chiang, Dirk Sachse. Abrupt change in tropical Pacific
climate mean state during the Little Ice Age. Communications Earth &
Environment, 2023; 4 (1) DOI: 10.1038/s43247-023-00882-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/07/230703133053.htm

--- up 1 year, 18 weeks, 10 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)