MSGID: 1:317/3 64a3a08d   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    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)   
   SEEN-BY: 15/0 106/201 114/705 123/120 153/7715 218/700 226/30 227/114   
   SEEN-BY: 229/110 112 113 307 317 400 426 428 470 664 700 291/111 292/854   
   SEEN-BY: 298/25 305/3 317/3 320/219 396/45 5075/35   
   PATH: 317/3 229/426