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Reduced N-fixation in the Low Latitude Atlantic during the Warmer Pliocene

Date:
23
Sunday
March
2025
Lecture / Seminar
Time: 11:00-12:00
Location: Sussman Family Building for Environmental Sciences
Lecturer: Maayan Yehudai
Abstract: N2 fixation is the primary pathway by which bioavailable nitrogen is added to th ... Read more N2 fixation is the primary pathway by which bioavailable nitrogen is added to theoceans. However, the drivers of N2 fixation on orbital timescales are uncertain. Wepresent high-resolution foraminifera-bound (FB) δ15N records from the Westernand Eastern tropical Atlantic Ocean (WTA and ETA respectively) throughout thelate Pliocene (~3.60 to ~1.97 Ma), where WTA ODP Site 999 represents N2fixation changes and EEA ODP Site 662 represents changes in pycnocline δ15N.Our results show that, compared to the past 160 ka, N2 fixation in the WTA wassignificantly lower throughout the late Pliocene as reflected by an average of ~2 ‰higher FB-δ15N values. A possible explanation to the higher Pliocene FB-δ15N inthe WTA could be lower rates of global denitrification that were balanced by lowerglobal N2 fixation levels. We suggest that this reduced N2 fixation was due todecreased excess P in the pycnocline/subsurface ocean, driven by lower globalwater column denitrification. This finding implies a coupling between decreasedwater column denitrification and reduced level N2 fixation rates under warmerclimates.On orbital timescales, our N2 fixation record display obliquity-paced cycles thatprogressively intensified after the Northern Hemisphere glaciation intensification ~2.8 Ma, and the onset of equatorial upwelling pulses documented during glacialperiods in the EEA (ODP Site 662; [1]). The observed changes in N2 fixation of thelast 160 ka were previously explained by precession-paced upwelling in the EEAthat imported excess P into the oligotrophic WTA [2]. However, precessionalcyclicity is not dominant in the Pliocene FB- δ15N, which calls for other candidatesto explain the variations after 2.8 Ma. The best explanation is a response to sealevelpaced sedimentary denitrification. Glacial lower sea levels exposedcontinental shelves, reducing regional benthic denitrification and inhibiting thesupply of excess P, thereby limiting N2 fixation in the WTA, whereas interglacialsubmerged shelves increased excess P availability.
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It’s an Emergency: What It Means to Be a Scientist in an Era of Climate and Ecological Breakdown

Date:
30
Sunday
March
2025
Lecture / Seminar
Time: 13:00-14:00
Title: IES- Institute For Environmental Sustainability Initiative seminar series 2025-2026
Location: Nella and Leon Benoziyo Building for Plant and Environmental Sciences
Lecturer: Dr. Avner Gross
Organizer: The Institute for Environmental Sustainability

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    The Holocene temperature and CO2 conundrum: a long-term perspective from earlier interglacials

    Date:
    16
    Sunday
    March
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Yair Rosenthal
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: The pre-industrial Holocene is unique among pastinterglacials due to a modest, b ... Read more The pre-industrial Holocene is unique among pastinterglacials due to a modest, but notable increase inatmospheric CO2 and methane (CH4) during the latter halfof the period despite an expected decrease given orbitalparameters. Although the causes for this increase,anthropogenic or natural are debated, all climate modelssimulate an increase in global mean temperature inresponse to the increase in the greenhouse gases. Yet,many proxy reconstructions, interpreted to reflect themean annual temperatures, indicate peak temperatures inthe first half of the Holocene, arguably exceeding modernmean annual temperatures followed by cooling through thepreindustrial period. This significant model-datadiscrepancy, known as the Holocene temperatureconundrum, and the debate on the cause of the CO2increase has undermined confidence in future climatemodel predications. In this talk I’ll offer new perspectiveson both issues.
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    The Clore Center for Biological Physics

    Date:
    23
    Sunday
    February
    2025
    Lecture / Seminar
    Time: 13:15-14:30
    Title: What can microbes tell us about their environment
    Location: Nella and Leon Benoziyo Physics Library
    Lecturer: Dr. David Zeevi
    Contact: debbie.hen@weizmann.ac.il
    Abstract: Microbial communities act as living sensors of their environment, continuously a ... Read more Microbial communities act as living sensors of their environment, continuously adapting to and recording changes in their surroundings across temporal and spatial scales. This capacity, combined with their central role in global biogeochemical cycles, makes microbes ideal indicators of ecosystem health. However, our understanding of how these communities respond to anthropogenic perturbations remains limited. In this talk, I will present two complementary approaches to decode environmental information from microbial communities. First, I will show that environmental temperature can be accurately predicted from microbial DNA composition alone, revealing fundamental principles of genome-wide thermal adaptation that transcend ecosystem boundaries. This work uncovers how evolutionary pressures shape microbial genomes across diverse habitats and provides insights into long-term community responses to climate change. Second, I will introduce a novel approach for measuring real-time bacterial growth rates in natural environments from a single sample, without prior knowledge on community composition. This method could enable us to track immediate ecological responses to environmental perturbations. By combining these evolutionary and ecological perspectives, we can begin to establish universal principles governing microbial responses to environmental change across different timescales. This multi-scale understanding is crucial for predicting and potentially mitigating the impacts of human activities on microbial ecosystems, from soil degradation to climate change.FOR THE LATEST UPDATES AND CONTENT ON SOFT MATTER AND BIOLOGICAL PHYSICS AT THE WEIZMANN, VISIT OUR WEBSITE: https://www.biosoftweizmann.com/
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    Submesoscale ocean circulation: plenty of room at the bottom

    Date:
    23
    Sunday
    February
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Aviv Solodoch
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Sub-mesoscale (SMS, <10 km scale) ocean circulation is characterized by high ... Read more Sub-mesoscale (SMS, <10 km scale) ocean circulation is characterized by high vorticity and deviation from geostrophic balance. It can result in large effects on biology and chemistry due to the large vertical velocities (x10-100 than mesoscale) and resulting down/up welling circulations, as well as significant effects on material retaining and dispersion. Modelling and observing the Submesoscale is challenging due to stringent demands on spatio-termpoal resolution, and due to its strong interactions with both larger (mesoscale) and smaller (turbulence and waves) circulations. I will report on the first Sub-mesoscale-resolving numerical modelling study in the East Mediterranean Sea, and (likely universal) findings on the patterns of cross-scale energy exchange between the Sub-Mesoscale and mesoscale circulation, which controls the seasonal evolution of both circulations. Secondly I will show in the model boundary current variability can spawn Sub-Mesoscales year-round (while open ocean formation is largely limited to winter). This will be backed by our (and the first) systematic observations of a Sub-mesoscale vortex formed in summertime via boundary current meandering.  
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    Interactions between cyclones and mesoscale eddies in the Mediterranean Sea

    Date:
    16
    Sunday
    February
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Ehud Strobach
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Mesoscale eddies dominate global ocean kinetic energy and are responsible for ef ... Read more Mesoscale eddies dominate global ocean kinetic energy and are responsible for efficiently transferring ocean properties. The influence of ocean eddies in the western boundary currents on storm tracks has been studied in recent years, and their importance in regulating mid-latitude precipitation is now recognized. Unlike western boundary currents, mesoscale eddies in the Mediterranean Sea (MS) are smaller and less intense. Yet, the MS is rich in mesoscale activity, and its proximity to densely populated regions suggests that even a small change may have a large impact, which remains underexplored. In this talk, I present several recent studies in which we investigated the interactions between mesoscale eddies and cyclones in the Mediterranean region. These studies focused on specific Mediterranean tropical-like cyclones (medicanes), analyzing their evolution under different sea conditions using observations and model simulations. We find that mesoscale eddies in the MS can change the intensity and track of cyclones and, consequently, affect their resulting rainfall distribution over land. In general, warm-core eddies tend to intensify cyclones and increase precipitation above them relative to cold-core eddies. Additionally, we observe a general increase in surface ocean biogeochemical properties, such as phytoplankton and chlorophyll, following cyclone passages. This increase is driven by upwelling and vertical mixing, though the relative importance of these processes differs between warm- and cold-core eddies.
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    Climate and Solar Variability: A Critical Evaluation

    Date:
    09
    Sunday
    February
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Nathan Steiger
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: It has been claimed that solar variability is the largest driver of climatic var ... Read more It has been claimed that solar variability is the largest driver of climatic variability across thePhanerozoic eon and that it accounts for ½ to ⅔ of20th century warming. Apparent evidence insupport of these claims has been mustered frommodeling work along with paleoclimatic, oceanographic, and other observational datasets.Here I will show that this research fails to replicate. I additionally find that many studies claiming tosupport a strong solar-climate link suffer from fundamental statistical and conceptual errors thatinvalidate their results.
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    Methane mitigation by unique redox couplings in freshwater sediments

    Date:
    02
    Sunday
    February
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Orit Sivan
    Abstract: This talk tests the ability of natural freshwater lakes and margins to attenuate ... Read more This talk tests the ability of natural freshwater lakes and margins to attenuate the emissions ofthe greenhouse gas methane (CH4) to the atmosphere under warming climate. I will show howmicrobial communities manage to survive and mitigate methane emissions under energylimited, highly reduced conditions of deep methanogenic lake sediments, through redoxcouplings of methane to Mn-Fe-N. Complex redox couplings between those species were alsoexplored in thermokarst lakes and margins, which are extensively formed by permafrost thawin the Arctic. The cycles were quantified using geochemical and microbial profiles, togetherwith stable isotope probing experiments close to natural conditions. The profiles andincubations show active microbial population that exhibit surprisingly both aerobic andanaerobic methane oxidation in methanogenic sediments and upland Arctic soils, fueled bynitrogen and iron redox cycles.
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    Allochthonous groundwater microorganisms affect coastal seawater microbial abundance, activity and diversity

    Date:
    19
    Sunday
    January
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman building
    Abstract: Submarine groundwater discharge (SGD) is a globally important processsupplying n ... Read more Submarine groundwater discharge (SGD) is a globally important processsupplying nutrients and trace elements to the coastal environment, thusplaying a pivotal role in sustaining marine primary productivity. Along withnutrients, groundwater also contains allochthonous microbes that aredischarged from the terrestrial subsurface into the sea. Currently, little isknown about the interactions between groundwater-borne and coastalseawater microbial populations, and groundwater microbes' role uponintroduction to coastal seawater populations. In the current study weinvestigated seawater microbial abundance, activity and diversity in a sitestrongly influenced by SGD. In addition, through laboratory-controlledbottle incubations, we mimicked different mixing scenarios betweengroundwater and seawater. Our results demonstrate that the addition of0.1 μm filtered groundwater stimulated heterotrophic activity andincreased microbial abundance compared to control coastal seawater,whereas 0.22 μm filtration treatments induced primary productivity andSynechococcus growth. 16S rRNA gene sequencing showed a strongshift from a SAR11-rich community in the control samples toRhodobacteraceae dominance in the <0.1 μm treatment, in agreementwith Rhodobacteraceae enrichment in the SGD field site. These resultssuggest that microbes delivered by SGD may affect the abundance,activity and diversity of intrinsic microbes in coastal seawater, highlightingthe cryptic interplay between groundwater and seawater microbes incoastal environments, which has important implications for carboncycling.
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    Making Climate Tech Work – Policies that Drive Innovation

    Date:
    22
    Sunday
    December
    2024
    Lecture / Seminar
    Time: 13:00-14:00
    Location: Nella and Leon Benoziyo Building for Plant and Environmental Sciences
    Lecturer: Prof. Alon Tal
    Organizer: Sustainability and Energy Research Initiative (SAERI)
    Contact: merav.hagag@weizmann.ac.il

    Multi-level ecosystem response to drying climate trends

    Date:
    22
    Sunday
    December
    2024
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Ehud Meron
    Abstract: Climate change and the development of drier climates threatenecosystems’ healt ... Read more Climate change and the development of drier climates threatenecosystems’ health and the services they provide to humans.Understanding ecosystem response to drier climates may provide clueson improving their functioning and resilience. This response is likely toinvolve mechanisms operating at different levels of ecologicalorganization. At the single-plant level, phenotypic changes can occur; atthe population level, spatial patterns can form; and at the communitylevel, community reassembly and biodiversity changes can occur.These mechanisms must affect one another, as stress relaxation byone mechanism weakens the driving forces of other mechanisms, butcomplex ecosystem responses involving coupled mechanisms havehardly been studied. In this talk I will focus on the interplay betweenphenotypic changes and spatial patterning and between spatialpatterning and community reassembly. Using mathematical models ofwater-limited plant communities, I will show that incorporatingphenotypic plasticity into vegetation pattern-formation theory canresolve two outstanding puzzles associated with the fascinatingNamibian fairy circle phenomenon and describe a predicted bufferingeffect of spatial patterning on community composition along rainfallgradients. Possible implications of these results to ecosystemfunctioning in stressed environments will be discussed.
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    ABC CHATS: Shira Eting

    Date:
    18
    Wednesday
    December
    2024
    Lecture / Seminar
    Time: 14:00-15:30
    Title: Based on values, Delivering value
    Location: George and Esther Sagan Students' Residence Hall
    Lecturer: Shira Eting - Vintage Investment Partners
    Contact: Reut.magor@weizmann.ac.il
    Abstract: During her conversation, Shira will share her personal journey and share what ha ... Read more During her conversation, Shira will share her personal journey and share what has led her to each decision and what are her key learnings.She will also share more about her position today as a Partner at Vintage, leading their investments in Healthcare and Climate.Join our ABC CHATS, Where CEOs share their ABC’s on scientific leadership, breakthroughs and failures throughout their personal stories
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    Multi-level ecosystem response to drying climate trends

    Date:
    17
    Tuesday
    December
    2024
    Lecture / Seminar
    Time: 16:46-17:46
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Ehud Meron

    Fundamentals of Remote Sensing and Machine Learning for Earth Science

    Date:
    01
    Sunday
    December
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Anna Brook
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Our Laboratory focuses on research that drives technological, environmental and ... Read more Our Laboratory focuses on research that drives technological, environmental and social change. It includes advanced technologies in the social aspect of environment management, embracing the complexity of the human-environment relationship, and physical model development for complex and non-trivial real-world problems in the era of climate change. Our ultimate goal is to bridge the gap between machine learning and geoscience for sustainability and environmental management at the national and international (mainly in the Mediterranean) scales. We understand that machine learning, in general, and deep learning, in particular, offer promising tools to build new data-driven models for Earth system components and thus build our understanding of ecosystems. Yet, accepting that data-driven machine learning approaches in geoscientific research cannot replace physical modelling but strongly complement and enrich it. Our primary scientific interests are developing hybrid approaches, coupling physical processes (physical laws and physics-domain-specific knowledge) with the versatility of data-driven machine learning, also known as physics-aware machine learning, to better understand the ecosystems, biodiversity, dynamic processes and environmental responses to stressors, and emphasizing sustainability and decision support system development aligned with the UN Sustainable Development Goals (SDGs).
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    PhD thesis defense- Avia Mizrachi

    Date:
    11
    Monday
    November
    2024
    Lecture / Seminar
    Time: 14:00-15:00
    Title: Phenotypic variability and cell fate determination in marine diatoms in response to environmental stress
    Location: Nella and Leon Benoziyo Building for Plant and Environmental Sciences
    Lecturer: Avia Mizrachi
    Organizer: Department of Plant and Environmental Sciences
    Contact: avia.mizrachi@weizmann.ac.il

    Late Oxygenation of Marine Environments Revealed by Dolomite U-Pb Dating

    Date:
    10
    Sunday
    November
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Uri Ryb
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: causal relationships between evolution and oxygenation of the ocean are vigorou ... Read more causal relationships between evolution and oxygenation of the ocean are vigorously debated. At the heart of these uncertainties are inconsistencies among reconstructed timelines for the rise of O2 in marine habitats. Attempts to reconstruct the timing of marine oxygenation are often based on redox-sensitive geochemical proxies that are prone to post-depositional alteration. Thus, developing new proxies, more resistant to such alteration, is an important direction forward for constraining major changes in atmospheric and marine oxygen levels. Here, we utilize U–Pb dating in dolomite to reconstruct their (re)crystallization ages and initial 207Pb/206Pb ratios; we find that they are systematically younger and lower than expected, respectively. These observations are explained by the resetting of the U–Pb system long after deposition, followed by further evolution in a closed system. Initial 207Pb/206Pb ratios have decreased from expected terrestrial values in the interval between deposition and (re)crystallization, consistent with U decay, and can therefore be used to reconstruct the initial 238U/206Pb ratios during deposition. Within our dataset initial 238U/206Pb ratios remained low in Proterozoic to mid-Paleozoic samples and increased dramatically in samples from the late-Paleozoic–early- Mesozoic Eras. This rise is attributed to a higher ratio of U to Pb in seawater that in turn influenced the fluid composition of carbonate crystallization sites. Accordingly, we interpret the temporal shift in initial 238U/206Pb ratios to reflect a late-Paleozoic increase in oxygenation of marine environments, corroborating previously documented shifts in some redox-sensitive proxies. This timeline is consistent with evolution-driven mechanisms for the oxygenation of late Paleozoic marine environments and with suggestions that Neoproterozoic and early Paleozoic animals thrived in oceans that overall and on long time scales were oxygen-limited compared to the modern ocean.
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    Data synthesis to assess the effects of climate change on agricultural production and food security

    Date:
    30
    Sunday
    June
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: David Makowski
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Climate change is having an impact on agricultural production and food security ... Read more Climate change is having an impact on agricultural production and food security. Rising temperatures, changes in rainfall patterns and extreme weather events can reduce crop yields, sometimes dramatically. However, climate change can also offer new opportunities, by generating more favorable climatic conditions for agricultural production in certain regions that were previously less productive. In order to assess the positive and negative impacts of climate change on agriculture and identify effective adaptation strategies, scientists have produced massive amounts of data during the last two decades, conducting local experiments in agricultural plots and using models to simulate the effect of climate on crop yields. In most cases, these data are not pooled together and are analyzed separately by different groups of scientists to assess the effects of climate change at a local level, without any attempt to upscale the results at a larger scale. Yet, if brought together, these data represent a rich source of information that are relevant to analyze the effect of climate across diverse environmental conditions. The wealth of data available has led to the emergence of a new type of scientific activity, involving the retrieval of all available data on a given subject and their synthesis into more robust and generic results. In this talk, I review the statistical methods available to synthesize data generated in studies quantifying the effect of climate change on agriculture. I discuss both the most classic methods - such as meta-analysis - and more recent methods based on machine learning. In particular, I show how this approach can be used to map the impact of climate change on a large scale (national, continental and global) from local data. I illustrate these methods in several case studies and present several research perspectives in this area.
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    Plan A+ - How geoengineering using stratospheric aerosols could play a role in climate policy

    Date:
    16
    Sunday
    June
    2024
    Lecture / Seminar
    Time: 13:00-14:00
    Location: https://weizmann.zoom.us/j/98884644964?pwd=SUF0cnVEZndYWmw1azFPQlhrTStuQT09
    Lecturer: Dr. Peter Irvine
    Organizer: Sustainability and Energy Research Initiative (SAERI)
    Contact: yuval.rosenberg@weizmann.ac.il
    Details: https://weizmann.zoom.us/j/98884644964?pwd=SUF0cnVEZndYWmw1azFPQlhrTStuQT09 Mee ... Read more https://weizmann.zoom.us/j/98884644964?pwd=SUF0cnVEZndYWmw1azFPQlhrTStuQT09 Meeting ID: 988 8464 4964 Password: 149775
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    Floods in a warming climate: what are the missing puzzle pieces?

    Date:
    19
    Sunday
    May
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Efrat Morin
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Flood is the outcome of complex processes interacting at a range of scales. Floo ... Read more Flood is the outcome of complex processes interacting at a range of scales. Flood generation and its magnitude depend on different precipitation and surface properties. As the climate becomes warmer globally, precipitation patterns are changing and, consequently, altering flood regimes. Resolving the expected changes in flood properties requires examining projections of precipitation features most correlated with floods. While the redistribution of mean annual precipitation amounts is generally known, the trends in many other essential factors controlling floods are yet to be resolved. For example, flash flood magnitude is sensitive to space-time rainstorm properties such as areal coverage or storm speed. Still, knowledge of how these properties are affected by global warming is lacking. Maximal rain rates for duration relevant to the watershed’s response time are also crucial parameters controlling the flood discharge. There is some understanding of how extreme rain rates change, but the magnitude and sign depend on the rain duration considered. Changes in frequency and the intra-seasonal distribution of precipitation events also affect flood regimes. Finally, watersheds of different properties are sensitive to different precipitation features, and thus, different watersheds may respond differently to global warming. In this talk, we will present the complexity of flood response under global warming and then focus on two questions: 1) how does global warming affect heavy precipitation events (HPEs) in the eastern Mediterranean, and 2) how these effects are imprinted in the resulting floods in small-medium Mediterranean watersheds. We simulated 41 eastern Mediterranean HPEs with the high-resolution weather research and forecasting (WRF) model. Each event was simulated twice: under historical conditions and at the end of the 21st-century conditions (RCP8.5 scenario) using the “pseudo global warming” approach. Comparison of precipitation patterns from the paired simulations revealed that heavy precipitation events in our region are expected to become drier and more spatiotemporally concentrated, i.e., we expect higher rain rates on smaller coverage areas and shorter storm durations that, in total, yield lower amounts of rainfall. These effects have some contradicting signs, and their full hydrological impact on streamflow peak discharge and volume was further explored. Ensembles of spatially-shifted rainfall data from the simulated HPEs were input to a high-resolution distributed hydrological model (GB-HYDRA) representing four small-medium-size watersheds (18–69 km2) in the eastern Mediterranean (Ramot Menashe). Flow volume is significantly reduced in future HPEs, while the change in flood peak is more complicated due to the combined effect of precipitation amount (decreasing) and precipitation rate (increasing). For the watersheds examined in this research, which are mostly agricultural, flood peaks at the watershed outlets are mostly reduced. The dynamics of flood generation at sub-watersheds of different sizes and properties are further examined in this research to understand scenarios for lowering or increasing flood peaks. This study emphasizes that detecting and quantifying global warming impact on space-time precipitation patterns is essential for flood regime projection.
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    Lake Kinneret in a Changing Environment

    Date:
    12
    Sunday
    May
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Yael Amitai
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Located in a highly sensitive subtropical climate area and a densely populated a ... Read more Located in a highly sensitive subtropical climate area and a densely populated area, Lake Kinneret is poised to undergo both natural and human-induced transformations in the coming decades. The lake is thermally stratified throughout most of the year and mixes thoroughly each winter when the epilimnion (upper layer) water temperature reaches equilibrium with the hypolimnion (bottom layer) water temperature by surface cooling and turbulence. Both the stratified and the fully mixed periods has a significant role in the Kinneret’s ecological system. Observation shows that air above the Lake is warming in a rate of 0.4oC/decade, while the epilimnion and hypolimnion are warming in a rate of 0.3oC/decade and 0.1oC/decade, respectively, for the last 50 years. Therefore, stratification strength and duration is anticipated to change and impact the lake’s ecosystem. Additionally, the sequence of drought periods and the expected future rise in water demands from Lake Kinneret formed the basis for the government's decision to channel desalinated water, via the natural course of the Tzalmon Stream, to the lake to ensure its operational functionality at high levels. Using a 3D hydrodynamic model forced by short and long-term forecasts the above scenarios are examined and analyzed. A simulation forced by regional atmospheric RCP4.5 climate change scenario spanning from 2010-2070 show continuous warming followed by abrupt cooling of the lake water around the year 2065. This result, presumably due to enhanced latent heat loss, suggest a restrain the dramatic anticipated change in the lake stratification.
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    Benthic side control on the chemical composition of the ocean

    Date:
    07
    Sunday
    April
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Zvi Steiner
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: The sediment – bottom-water interface is suggested as a key control on the ch ... Read more The sediment – bottom-water interface is suggested as a key control on the chemical composition of the ocean by studies of trace elements in the ocean water-column, yet data regarding trace element fluxes and interactions taking place in the top ten cm of abyssal sediments are scarce. To bridge this gap, I analysed the trace and major element composition of porewater and sediment of red-clay sediment from the abyssal North Pacific, and hydrothermally influenced sediment from the Mid-Atlantic Ridge. The top sediment at both study regions is aerobic, nevertheless, there is large variability in the porewater concentrations of many elements at the top five cm. The North Pacific red-clay sediment is a source of cobalt, nickel, copper, arsenic, vanadium and barium to the deep-ocean, the magnitude of these fluxes is consistent with fluxes calculated based on the water-column distribution of most elements, and are equivalent to the global supply of these elements by rivers. The hydrothermally influenced sediment is a strong source of copper, zinc and cobalt up to three km from the vent due to oxidation of sulfide minerals. Close to the vents, the sediment is high in iron oxyhydroxides that adsorb the oxyanions vanadate, arsenate and phosphate, acting as a sink for these elements. The results of this study highlight the importance of red-clay sediment in shaping the chemical composition of the ocean, and suggest an important role for hydrothermally influenced sediment in modulating the contributions of hydrothermal vents to ocean biogeochemistry.
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    Large scale circulation adjustments to aerosol-cloud interactions and its radiative effect

    Date:
    31
    Sunday
    March
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Guy Dagan
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: The impact of anthropogenic aerosols on clouds is a leading source of uncertaint ... Read more The impact of anthropogenic aerosols on clouds is a leading source of uncertainty in estimating the effect of human activity on the climate system. The challenge lies in the scale difference between clouds (~1-10 km) and general circulation and climate (~1000 km). To address this, we utilize three different novel sets of simulations that allow to resolve convection while also including a epresentation of large-scale processes. Our findings demonstrate that aerosol-cloud interaction intensifies tropical overturning circulation. Employing a weak temperature gradient approximation, we attribute variations in circulation to clear-sky humidity changes driven by warm rain suppression by aerosols. In two sets of simulations accounting for sub-tropical-tropical coupling, we show that aerosol-driven sub-tropical rain suppression leads to increased advection of cold and moist air from the sub-tropics to the tropics, thus enhancing tropical cloudiness. The increased tropical cloudiness has a strong cooling effect by reflecting more of the incoming solar radiation. The classical “aerosol-cloud lifetime effect” is shown here to have a strong remote effect (sub-tropical aerosols increase cloudiness in the tropics), thus widening the concept of cloud adjustments to aerosol perturbation with important implications for marine cloud brightening.
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    EPS AI discussion seminar - Neural General Circulation Models for weather and climate predictions

    Date:
    25
    Monday
    March
    2024
    Lecture / Seminar
    Time: 16:00
    Location: also via zoom: https://weizmann.zoom.us/j/95890082380?pwd=TnZxc1NoSkxUbjM3SVB0dVpCdVRtZz09
    Lecturer: Janni Yuval
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il

    EPS Departmental Seminar; Challenges and opportunities in global storm resolving climate models

    Date:
    25
    Sunday
    February
    2024
    Lecture / Seminar
    Time: 11:00
    Title: EPS Departmental Seminar
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Dr. Ilai Guendelman
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il

    The geologic history of marine dissolved organic carbon from iron (oxyhydr)oxides

    Date:
    11
    Sunday
    February
    2024
    Lecture / Seminar
    Time: 11:00
    Title: EPS Department Seminar
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Nir Galili
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il

    The Southern Lights — Rhodopsin Complexes Discovered in an Algae Near Antarctica Can Help Unravel the Secrets of the Brain

    Date:
    16
    Monday
    October
    2023
    Colloquium
    Time: 11:00-12:15
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Moran Shalev-Benami
    Organizer: Department of Chemical and Structural Biology
    Contact: sarah.amzallag@weizmann.ac.il
    Abstract: Rhodopsins are a ubiquitous family of light sensing/signaling proteins. In recen ... Read more Rhodopsins are a ubiquitous family of light sensing/signaling proteins. In recent work, our group discovered an intriguing family of rhodopsins in algae: the bestrhodopsins. Through cryo-EM and comprehensive biochemical and electrophysiological studies, we showed that bestrhodopsins are fusions of rhodopsins and ion channels which assemble as mega-complexes to enable light-controlled passage of ions across membranes. Regulation of a classical ion channel by an attached photoreceptor has never been found before in nature, and previous attempts to engineer light-regulated fused channels have yielded limited success. The discovery and characterization of bestrhodopsins thus provide a new template for designing proteins with light-sensing and ion-conducting activities, as well as represent a platform for regulating cellular signaling in living organisms using light. These findings are therefore not only important as a basic scientific discovery but also for the field of optogenetics where neural activity is controlled by light. In the present talk, I will present the discovery of the bestrhodopsins, and explain how we use our cryo-EM work for structure-based design of dramatically improved tools to manipulate signaling cascades in cells by light control, paving the way for the next generation of optogenetics tools to study brain function in vivo.
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    Gallery: The Southern Lights — Rhodopsin Complexes Discovered in an Algae Near Antarctica Can Help Unravel the Secrets of the Brain Gallery
    The Southern Lights — Rhodopsin Complexes Discovered in an Algae Near Antarctica Can Help Unravel the Secrets of the Brain Colloquium website

    Quantifying the Global and Regional Contribution of Terrestrial Carbon Pools to the Land Sink

    Date:
    10
    Sunday
    September
    2023
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Yinon Bar-On
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Terrestrial sequestration of carbon has mitigated ≈30% of anthropogenic carbo ... Read more Terrestrial sequestration of carbon has mitigated ≈30% of anthropogenic carbon emissions. However its distribution across different pools—live or dead biomass, and soil and sedimentary organic carbon— which has important implications for future climate change mitigation, remains uncertain. By analyzing global observational datasets of changes in terrestrial carbon pools, we are able to partition carbon that has been sequestered on land between 1992-2019 into live biomass and non-living organic carbon pools. We compare our observation-based estimates against predictions of global vegetation models and identify key processes that are not included in most models that can help align the models with observations. We find that most terrestrial carbon gains are sequestered as non-living organic matter, and thus more persistent than previously appreciated, with a substantial fraction linked to human activities such as river damming, wood harvest, and garbage disposal in landfills.
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    Ultra-Repellent Aerophilic Surfaces Underwater”

    Date:
    30
    Wednesday
    August
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Alexander B. Tesler
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract: Wetting describes the ability of liquids to maintain contact with a solid surfac ... Read more Wetting describes the ability of liquids to maintain contact with a solid surface, a phenomenon that is ubiquitous in nature.1 However, in engineering and medical applications, contact of solid surfaces with aqueous media leads to undesirable phenomena such as corrosion, chemo- and biofouling, which have extremely negative economic, health, and environmental impacts. Therefore, control of wetting on solid surfaces is key to mitigating its detrimental effects. The latter can be achieved by minimizing the contact of the solid substrate with aqueous media, so-called superhydrophobic surfaces (SHS). Although SHS have been studied for decades to overcome wetting challenges,2 they are still rarely used in engineering applications. When immersed underwater, a special type of SHS can trap air on its surface, so-called air plastron, also known as an aerophilic surface. To date, plastrons have been reported to be impractical for underwater engineering due to their short lifetime. Here, I will describe aerophilic surfaces made of titanium alloy (Ti) with an extended lifetime of plastron conserved for months underwater.3 The extended methodology was developed to unambiguously describe the wetting regime on such aerophilic surfaces since conventional goniometric measurements are simply impractical. My aerophilic surfaces drastically reduce the adhesion of blood, and when immersed in aqueous media, prevent the adhesion of bacteria, and marine organisms such as barnacles, and mussels. Applying thermodynamic stability theories, we describe a generic strategy to achieve long-term stability of plastron on aerophilic surfaces for demanding and hitherto unattainable applications. (1) Quéré, D. Wetting and Roughness. Annual Review of Materials Research 2008, 38 (1), 71-99. (2) Cassie, A. B. D.; Baxter, S. Wettability of porous surfaces. Transactions of the Faraday Society 1944, 40, 546-551. (3) Tesler, A.B.;* Kolle, S.; Prado, L.H.; Thievessen, I.; Böhringer, D.; Backholm, M.; Karunakaran, B.; Nurmi, H.A.; Latikka, M.; Fischer, L.; Stafslien, S.; Cenev, Z.M.; Timonen, J.V.I.; Bruns, M.; Mazare, A.; Lohbauer, U.; Virtanen, S.; Fabry, B.; Schmuki, P.; Ras, R.H.A.; Aizenberg, J.; Goldmann, W.H. Long-Lasting Aerophilic Metallic Surfaces Underwater. Nature Materials 2023, accepted. *Corresponding author
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    A Neolithic Tsunami Event along the Eastern Mediterranean Littoral: A Transdisciplinary Research at the Coast of Dor Israel

    Date:
    09
    Sunday
    July
    2023
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Gilad Steinberg
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Tsunami events in antiquity had a profound influence on coastal societies. Six t ... Read more Tsunami events in antiquity had a profound influence on coastal societies. Six thousand years of historical records and geological data show that tsunamis are a common phenomenon affecting the eastern Mediterranean coastline. However, the possible impact of older tsunamis on prehistoric societies has not been investigated. Here we report, based on optically stimulated luminescence chronology, the earliest documented Holocene tsunami event, between 9.91 to 9.29 ka (kilo-annum), from the eastern Mediterranean at Dor, Israel. Tsunami debris from the early Neolithic is composed of marine sand embedded within fresh-brackish wetland deposits. Global and local sea-level curves for the period, 9.91–9.29 ka, as well as surface elevation reconstructions, show that the tsunami had a run-up of at least ~16 m and traveled between 3.5 to 1.5 km inland from the palaeo-coastline. Submerged slump scars on the continental slope, 16 km west of Dor, point to the nearby “Dor complex” as a likely cause. The near absence of Pre-Pottery Neolithic A-B archaeological sites (11.70–9.80 cal. ka) suggests these sites were removed by the tsunami, whereas younger, late Pre-Pottery Neolithic B-C (9.25–8.35 cal. ka) and later Pottery-Neolithic sites (8.25–7.80 cal. ka) indicate resettlement following the event. The significant run-up of this event highlights the disruptive impact of tsunamis on past societies along the Levantine coast.
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    Vision and AI

    Date:
    01
    Thursday
    June
    2023
    Lecture / Seminar
    Time: 12:15-13:15
    Title: Spaceborne multi-view computational tomography (CT)
    Location: Jacob Ziskind Building
    Lecturer: Yoav Schechner
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: We describe new computer vision tasks stemming from upcoming multiview tomograph ... Read more We describe new computer vision tasks stemming from upcoming multiview tomography from space. Solutions involve both novel imaging hardware and computational algorithms, based on machine learning and differential rendering. This can transform climate research and medical X-ray CT. The key idea is that advanced computing can enable computed tomography of volumetric scenes, based scattered radiation. We describe an upcoming space mission (CloudCT, funded by the ERC). It has 10 nano-satellites that will fly in an unprecedented formation, to capture the same scene (cloud fields) from multiple views simultaneously, using special cameras. The satellites and cameras are built now. They - and the algorithms - are specified to meet computer vision tasks, including geometric and polarimetric self-calibration in orbit, and estimation of 3D volumetric distribution of matter and microphysical properties. Deep learning and differential rendering enable analysis to scale to big data downlinked from orbit. Core ideas are generalized for medical X-ray imaging, to enable significant reduction of dose and acquisition time, while extracting chemical properties per voxel. The creativity of the computer vision and graphics communities can assist in critical needs for society, and this talk points out relevant challenges.
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    Determining past lake temperatures in saline lake systems using fluid inclusions: an example from the Dead Sea

    Date:
    21
    Sunday
    May
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Niels Brall
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: In recent decades, various temperature proxies have been developed and further e ... Read more In recent decades, various temperature proxies have been developed and further established in the scientific community, at both low and high accuracy, however, not every method can be applied without restriction to all minerals or rocks. Evaporitic rocks, for example, are abundant chemical sediments at the Earth's surface that are deposited from supersaturated brines in marine, terrestrial, and lacustrine environments. Halite is the most abundant rock-forming mineral in this group, which during crystal formation entraps tiny water droplets (fluid inclusions, FIs) that store the chemical composition of the parent brine at a specific pressure-temperature dependent density. Such FIs are therefore excellent records of the original physicochemical conditions of the source brine. Brillouin spectroscopy (BS) is a novel laser-based technique that uses density fluctuations in FIs to directly measure entrapment temperatures and thus the initial brine temperature during crystal growth. In this seminar, the BS method will be introduced and two application cases will be presented using salt layers from the Dead Sea which were deposited during two interglacial periods. In addition to the basic principles, both the recommended sampling strategy and pitfalls along with associated limitations will be presented. The conclusion will be that the salt layers commonly deposited in the Dead Sea basin consist of two types that formed preferentially in summer (coarse-grained crystals) and winter (fine-grained crystals), which is mainly controlled by the degree of salt saturation of the lake water. Furthermore, it will be shown how (1) lake bottom temperatures have fluctuated seasonally (summer/winter), and that (2) paleo temperature trends can be reconstructed for an entire halite layer that was deposited during holomictic periods in the Dead Sea basin. This method is particularly promising for evaporites that formed near the surface if the material has not been affected by external processes such as tectonic burial/uplift, erosion, or mineral replacement.
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    Projecting the impacts of climate change on human society

    Date:
    14
    Sunday
    May
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Ram Fishman
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il

    Mortality – and survival through microbial interactions - in abundant marine cyanobacteria

    Date:
    02
    Tuesday
    May
    2023
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Daniel Sher
    Organizer: Department of Plant and Environmental Sciences
    Contact: david.zeevi@weizmann.ac.il

    Oceanic Internal Gravity Waves: sources, sinks, and interactions with the eddy field. 

    Date:
    30
    Sunday
    April
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Roy Barkan
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: The global oceanic overturning circulation and the transport of heat and dissolv ... Read more The global oceanic overturning circulation and the transport of heat and dissolved gases are strongly controlled by upper ocean turbulent mixing that is driven by the breaking of internal gravity waves (IWs). Understanding the life cycle of oceanic IWs, from generation to dissipation, is therefore crucial for improving the representation of ocean mixing in climate models, which do not resolve the IW field.  Oceanic IWs are observed to have a continuous energy distribution across spatial and temporal scales – an internal wave continuum – despite being forced primarily at near-inertial and tidal frequencies at large scales. The formation of the IW continuum and the associated energy transfer to dissipative scales have been traditionally attributed to wave-wave interactions and to Doppler shifting of wave frequencies by currents. Here, we provide evidence from realistic numerical simulations that oceanic eddies rapidly diffuse storm-forced wave energy across spatiotemporal scales, thereby playing a dominant role in the formation of the IW continuum and the corresponding spatiotemporal distribution of energy dissipation. We further demonstrate that winds can play an important role in damping oceanic IWs through current feedback.  This results in a substantial reduction in wind power input at near inertial frequencies and a net energy sink for internal tides.
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    Innovation & Public Policy to Solve Climate Change

    Date:
    19
    Sunday
    March
    2023
    Lecture / Seminar
    Time: 13:00-14:00
    Title: SAERI - Sustainability and Energy Research Initiative Seminar Series
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Mr. Ram Amar
    Organizer: Weizmann School of Science
    Contact: daphna.yahav@weizmann.ac.il
    Details: Host: Prof. Ron Milo The lecture will be held at the Benoziyo Biochemistry Buil ... Read more Host: Prof. Ron Milo The lecture will be held at the Benoziyo Biochemistry Building room 690
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    Reactive oxygen species regulation of cell to cell systemic signaling and acclimation in plants during stress

    Date:
    14
    Tuesday
    March
    2023
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Yosef Fichman
    Organizer: Department of Plant and Environmental Sciences
    Contact: merav.hagag@weizmann.ac.il
    Details: The lecture will be delivered at the Benoziyo Biochemistry Auditorium and via Zo ... Read more The lecture will be delivered at the Benoziyo Biochemistry Auditorium and via Zoom. For joining remotely, please use this link: https://weizmann.zoom.us/j/91945632908?pwd=ZmJseUdYYmlKQjN2K0ovREdpem1GUT09 Meeting ID: 919 4563 2908 Password: 350641
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    Abstract: Reactive oxygen species (ROS) play a key role in systemic cell to cell signaling ... Read more Reactive oxygen species (ROS) play a key role in systemic cell to cell signaling which is required for plant acclimation to different stresses, essential for the survival of plants. We recently developed a method to image real-time whole-plant accumulation of ROS and other systemic signals, and together with transcriptomic analysis and physiological measurements, we revealed the involvement of important signaling components in response to localized high light stress leading to systemic acquired acclimation (SAA) in Arabidopsis thaliana. The signal initiation and propagation maintenance are dependent on generation of ROS by RESPIRATORY BURST OXIDASE HOMOLOGS (RBOHs) in the apoplast and transport through the plasmodesmata, under the control of PLASMODESMATA LOCALIZED PROTEIN 1 (PDLP1) and PDLP5. Furthermore, we showed that phytochrome B acts in the same regulatory module as RBOHD and that it can regulate ROS production even if it is restricted to the cytosol. Additional proteins we discovered to function in the maintenance of the signal propagation, are aquaporin PLASMA INTRINSIC PROTEIN 2;1 (PIP2;1), that transport H2O2 across the plasma membrane and calcium channels including GLUTAMATE LIKE RECEPTORS 3.3 and 3.6 (GLR3.3 & GLR3.6), MECHANOSENSORS LIKE PROTEINS 2 and 3 (MSL2 & MSL3). Based on mutants and grafting experiments we identified the role of the ROS receptor HYDROGEN PEROXIDE INDUCED CALCIUM INCREASE 1 (HPCA1) in ROS cell to cell signal propagation, as well as the calcium signal propagation. We also reported that CALCINEURIN B-LIKE CALCIUM SENSOR 4 (CBL4), CBL4 INTERACTING PROTEIN KINASE 26 (CIPK26) and OPEN STOMATA 1 (OST1) are required for the cell-to-cell ROS signals. Altogether, screening more than 120 mutants, we shed light on the underling molecular mechanisms that coordinate the systemic cell to cell signals required for plant acclimation to stress. While most of our work focused on Arabidopsis, we were able to show the ROS auto propagation systemic signals are conserved in evolution and occur also in unicellular algae colonies, non-vascular plants and even mammalian cells. Thus, emphasizing the importance of the active process of cell-to-cell ROS signaling in communicating stress response signals between cells.
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    Ph.D. Defense Seminar -Temporal and spatial genetic diversity of a wild wheat population under climate change

    Date:
    06
    Monday
    March
    2023
    Lecture / Seminar
    Time: 15:00-16:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Tal Dahan-Meir
    Organizer: Department of Plant and Environmental Sciences
    Contact: tal.dahan@weizmann.ac.il

    Forecasting surface weather and storm tracks at one-month leads: role of the stratosphere and the Madden Julian Oscillation

    Date:
    05
    Sunday
    February
    2023
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Chaim Garfinkel
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: The traditional approach to weather forecasting on one- to two-week timescales u ... Read more The traditional approach to weather forecasting on one- to two-week timescales utilizes weather forecasting models, but on timescales longer than two weeks, the value of deterministic (or ensemble-based probabilistic) forecasts weakens. This is due to the presence of chaotic variability in the atmosphere. Yet certain modes of variability in the climate system have timescales longer than this two-week threshold, and the key to longer-scale prediction is to take advantage of these modes when they open up windows of opportunity. By understanding the impacts of these modes of variability on surface weather, the potential for improved forecasts on a monthly timescale can be demonstrated and eventually realized.  Two such classes of modes of variability are stratospheric variability (both in the tropical and polar stratosphere) and tropical tropospheric variability (e.g. the Madden-Julian Oscillation and El Nino). For example, both polar stratospheric sudden warmings and the Madden-Julian Oscillation have been shown to influence European and Mediterranean weather, but it is unclear (1) what mechanism(s) underlie these connections, (2) how far in advance the impacts can be predicted, (3) what governs the magnitude of the surface impact, and (4) how well models capture these connections. This talk will review progress made towards addressing these issues over the past several years in my group.
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    Silver mines, the rise of money and the advent of democracy

    Date:
    02
    Thursday
    February
    2023
    Lecture / Seminar
    Time: 14:00
    Title: EPS Department and Kimmel Center for Archaeological Science
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Prof. Francis Albarède
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Over the last 2½ millenia, the world economy depended on prevailing currencies: ... Read more Over the last 2½ millenia, the world economy depended on prevailing currencies: the Athenian owl (530- 168 BCE), the Roman denarius (211 BCE-250 AD), the Spanish piece-of-eight (16th to 18th C), and today the US dollar. These reference monies were accepted everywhere and all, at least in the beginning, were made of silver. What is so special about this metal? Silver is useless and rare, but still abundant enough to match the wealth of nations and of their long-distance trade. Silver ores are associated with rare and recent tectonic environments, the Mediterranean world, notably the periphery of the Aegean Sea and Southern Iberia, and the American cordillera, Peru and Mexico. In contrast, they were markedly scarce in South and East Asia. After the virtual destruction of soils by the Anatolian farmers at the end of the Bronze Age, the Near and Middle East societies depended almost exclusively on the agriculture of Egypt and Mesopotamia. The Late Bronze Age collapse (ca. 1200 BCE) corresponded to the migration of Greek people and resulted in the annihilation of all the empires outside of the flood plains. Silver by weight was nevertheless used to save populations from famine and trade wheat, barley and copper. Military innovations, hoplites and their phalanx, were, with silver mines, the main resources of the Greeks. Mercenaries received their wages in silver, notably through the tributes exacted in silver by the Achaemenid (Persion) kings. By minting silver, the returning Greek mercenaries emerged as strong middle classes . They soon claimed their share of the power, toppled the tyrants, and installed democracy in many poleis from Greece and Southern Italy. Modern economics teaches us that egalitarian distribution of wealth is unfortunately unstable and this case is well illustrated by Syracuse. At the beginning of the common era, the Roman Empire found itself the owner of centuries of silver extracted from Greece and from Iberia. This bullion was used to buy luxury products, frankincense from Arabia, spices and cotton from India, ivory and precious wood from Africa. Leakage of silver towards the Indian Ocean was so strong that coins were quickly debased by copper and by 250 AD most of the silver had been lost. The progressive replacement of silver by a bimetallic system, gold for the rich and bronze for the working class, progressively fractured the society and ushered the brutal Middle Age regimes. Silver famine had finally destroyed the democratic ideal of the Greeks. This is food for thought as disappearing mining resources may severely affect our current vision of societies.
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    A meta'omics perspective on the functional potential and regulation of metabolic activity in the global ocean microbiome

    Date:
    31
    Tuesday
    January
    2023
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Shinichi Sunagawa
    Organizer: Department of Plant and Environmental Sciences
    Contact: david.zeevi@weizmann.ac.il
    Details: Host: Dr. David Zeevi

    Insolation Forcing and Eastern Mediterranean aridity: Evidence from the Dead Sea and implications for climate projections

    Date:
    29
    Sunday
    January
    2023
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Yochanan Kushnir
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: The Mediterranean region stands out among other subtropical regions in its proje ... Read more The Mediterranean region stands out among other subtropical regions in its projected drying response to the global rise in atmospheric greenhouse gas concentrations. This drying trend has already emerged out of the normal, random climate variability in the sensitive Eastern Mediterranean (EM) region. To better understand the dynamical mechanisms responsible for this regional sensitivity, we turn to past protracted EM drying states during warm geological epochs. A unique view of the historical and pre-historical hydroclimate of the EM-Levant has been gleaned from the continued study of the sedimentary and geochemical record left by the lakes that filled the tectonic basin of the Dead Sea. We revisit the Late Quaternary sediment record retrieved during the 2010-2011 Dead Sea Deep Drilling Project (DSDDP). The sediments clearly indicate that the Levant was drier during past warm interglacials than during the adjacent glacials but nonetheless experienced large variations in the intensity of the regional aridity. During each interglacial, extended thick deposits of salts accumulated at the Lake bottom, during millennia of significant regional aridity and severely reduced Mediterranean rains. These dry states were interrupted by extended wet intervals, fed by rains that were supplied by a blend of tropical and Mediterranean moisture. To understand the underlying causes of the EM-Levant interglacial hydroclimate variations, we put the Dead Sea record in the context of the Northern Hemisphere orbital insolation variations and their impact on the global climate system. We show that the changes in EM hydroclimate portrayed by the DSDDP record during the interglacials, are entirely consistent with the response of the North Atlantic Ocean and the overlying atmosphere and surrounding land areas to the changes in the latitudinal insolation gradient, as determined by climate models and evident by surface temperature proxies. This perspective provides new information regarding the dynamical processes responsible for the ongoing, greenhouse gas forced, EM drying.
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    Persistent and concurrent weather extremes in present and future climates

    Date:
    22
    Sunday
    January
    2023
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Kai Kornhuber
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Recent severe summertime weather extremes in the Northern hemisphere extratropi ... Read more Recent severe summertime weather extremes in the Northern hemisphere extratropics such as the extraordinary 2021 North American Heatwave and the record-breaking floods in central Europe were in part driven by persistent circulation patterns in the tropospheric Jetstream. To what degree such circulation patterns will modulate extreme weather risk in a warming world is still uncertain and remains a highly debated topic in climate science. I will present results from recent studies that investigate physics of extraordinary extremes, future changes in weather persistence diagnosed by a feature tracking algorithm and future risks from concurrent extremes and associated impacts on crop production based on latest GGCMI-runs. A special emphasis will be placed on benchmarking the skill of CMIP5 and CMIP6 models to reproduce atmosphere dynamical mechanisms and associated extreme weather against reanalysis data short bio: Kai Kornhuber is an adjunct Associate Research Scientist at the Lamont-Doherty Earth Observatory, Columbia University in New York and a Senior Fellow on Climate Risks at the German Council on Foreign Relations. His research is concerned with physical drivers of extreme weather and climate events and associated societal impacts and risks under current and future climatic conditions. He is Founding Member of the EarthNetwork on Sustainable and Resilient Living in an Era of Increasing Disasters at Columbia’s Climate School, Co-Chair of the Compound Events Working Group at Risk-Kan, Steering Committee member of the HiWeather Project and a Co- Pi of the Project PERSEVERE within the BMBF Consortium.
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    The Israeli Climate Tech Ecosystem

    Date:
    15
    Sunday
    January
    2023
    Lecture / Seminar
    Time: 13:00-14:00
    Title: SAERI - Sustainability and Energy Research Initiative Seminar Series
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Mr. Uriel Klar
    Organizer: Weizmann School of Science
    Contact: daphna.yahav@weizmann.ac.il