Subj : New study reveals abrupt shift in tropic To : All From : ScienceDaily Date : Mon Jul 03 2023 22:30:28 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) .