Earth Sciences and geochemistry provide powerful tools to explore the processes that shape our planet. At Kiro Lab, we focus on studying the chemistry of the ocean and past environments to understand fundamental Earth system processes, such as the carbon cycle and climate dynamics. This understanding helps us to better interpret the natural variability of the Earth system and provides valuable insights into how we might respond to future climate change.
In our group, we explore the interplay between coastal and submarine environments, exploring their dynamics across diverse spatial and temporal scales. Our research aims to unravel the fundamental processes governing these environments, providing critical insights into their role in shaping our planet's past, present, and future.
Kushnir Y., Stein M., Biasutti M., Kiro Y., Goldsmith Y. & Goldstein S. L.
(2024)
Proceedings of the National Academy of Sciences - PNAS.
121,
47,
e240716612.
The mechanisms underlying the current greenhouse gas (GHG) forced decline in Mediterranean rainfall remain a matter of debate. To inform our understanding of the current and projected drying, we examined extended arid intervals in the late Quaternary, Eastern Mediterranean (EM) Levant indicated by substantial salt deposits in a Dead Sea sediment core covering the past 220 kyr. These arid events occurred during interglacials, when the Earth was at perihelion to the sun in boreal fall and during glacial-interglacial transitions, associated with icesheet melting. Climate models forced with realistic late Quaternary insolation variations show that when the Earth is closest to the Sun in boreal fall, the North Atlantic latitudinal surface temperature gradient in the winter intensifies. In response, the overlying midlatitude North Atlantic jet stream and the extratropical storm track move poleward while sea-level pressure rises in the subtropics. These changes bring about a weakening of the Mediterranean storm track and a decline in rainfall over the entire basin. During glacial-interglacial transitions, meltwater from continental icesheets forced abrupt subpolar North Atlantic cooling. This also strengthened the latitudinal surface temperature gradient, likely causing similar atmospheric response and aridity in the Mediterranean. There is a strong resemblance between this paleoclimate scenario and the climatic changes corresponding to the present and projected GHG drying of the EM. Hence, the late Quaternary palaeohydrology of the Dead Sea indicates an important North Atlantic centered response to external forcing, which leads to Mediterranean drying and is relevant in the present.
Sproson A. D., Yokoyama Y., Miyairi Y., Aze T., Clementi V. J., Riechelson H., Bova S. C., Rosenthal Y., Childress L. B., Aiello I. W., Avila A., Biggs W., Charles C. D., Cheung A. H., deLong K., Dove I. A., Du X., Estes E. R., Fuentes U., García-Lasanta C., Goldstein S. L., Golub A., Hagemann J. R., Hatfield R. G., Haynes L. L., Hess A. V., Irvali N., Kiro Y., Monteagudo M. M., Lambert J. E., Li C., Longo W. M., McGrath S., Robinson R. S., Sarao J., Taylor S., Wright J. D. & Yu S. M.
(2024)
Nature Geoscience.
17,
p. 450-457
Northern Hemisphere insolation intensity is roughly in phase with Southern Hemisphere climate proxies, leading to a common conclusion that northern insolation forces southern climate during the Late Quaternary. However, mid-latitude Southern Hemisphere records place the advance of Patagonian and New Zealand glaciers before the Last Glacial Maximum (29,00018,000 years ago) by several millennia. To resolve the cause(s) of nearly synchronous global climate change requires continuous archives of mid-latitude glacial activity for the last glacial cycle. Here we assess the position of the Patagonian Ice Sheets marine-terminating margin over the last ~89,000 years using a sedimentary-beryllium-isotope record from the Chilean margin to track the proximity of local glaciers. We find that glaciations and deglaciations are synchronous with or precede Northern Hemisphere ice sheets by thousands of years. Glacial expansion was driven by equatorward migration and strengthening of the southern westerly winds, linked to global cooling and a steeper meridional temperature gradient. Glacial terminations occurred when global warming coincided with increasing obliquity and dramatic Northern Hemisphere cooling. Our results suggest that, on orbital timescales, a complex interaction between mean global climate, obliquity and interhemispheric teleconnections could have led to near-synchronous global ice sheet evolution through displacements of the southern westerlies.
Yanuka-Golub K., Belkin N., Weber N., Mayyani M., Levy Y., Reznik I. J., Rubin-Blum M., Rahav E. & Kiro Y.
(2024)
Journal of geophysical research: Biogeosciences.
129,
2,
e2023JG007.
Submarine groundwater discharge (SGD) is a globally important process supplying nutrients and trace elements to the coastal environment, thus playing a pivotal role in sustaining marine primary productivity. Along with nutrients, groundwater also contains allochthonous microbes that are discharged from the terrestrial subsurface into the sea. Currently, little is known about the interactions between groundwater-borne and coastal seawater microbial populations, and groundwater microbes' role upon introduction to coastal seawater populations. Here, we investigated seawater microbial abundance, activity and diversity in a site strongly influenced by SGD. In addition, through laboratory-controlled bottle incubations, we mimicked different mixing scenarios between groundwater and seawater. Our results demonstrate that the addition of 0.1 μm filtered groundwater stimulated heterotrophic activity and increased microbial abundance compared to control coastal seawater, whereas 0.22 μm filtration treatments induced primary productivity and Synechococcus growth. 16S rRNA gene sequencing showed a strong shift from a SAR11-rich community in the control samples to Rhodobacteraceae dominance in the
