I’m a climate scientist at the School of Earth and Atmospheric Science at the Georgia Institute of Technology.
My research focuses on investigating how and why the Earth's climate has varied in the past inorder to better inform future climate projections. My work primarily involves reconstructing regional changes in ocean temperature, salinity, and circulation patterns over the last few thousand years by measuring stable isotopes and trace elements in coral skeletons. I’m also interested in the development of new proxies and methodologies to extend and improve our ability to reconstruct past climate, and data assimilation using large networks of proxy records to better understand large-scale patterns of climate change.
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See "Publications & Data" for a full list of publications and links to archived data
Coral oxygen isotope and in situ records capture the 2015/2016 El Niño event in the central equatorial Pacific - O'Connor et al., in review
Coral oxygen isotopes (δ18O) from the central equatorial Pacific provide monthly-resolved records of El Niño-Southern Oscillation (ENSO) activity over past centuries to millennia. However, calibration studies using in situ data to assess the relative contributions of warming and freshening to coral δ18O records are exceedingly rare. Here, we present six coral δ18O records and in situ temperature, salinity, and seawater δ18O data from Kiritimati Island (2°N, 15°W) spanning the very strong 2015/16 El Niño event. Local sea surface temperature (SST) anomalies of +2.4±0.4°C and seawater δ18O anomalies of -0.19±0.02‰ contribute to the observed coral δ18O anomalies of -0.58±0.05‰, consistent with a ~70% contribution from SST and ~30% from seawater δ18O. Our results demonstrate that Kiritimati coral δ18O records can provide reliable reconstructions even during the largest class of El Niño events.
Reproducibility of Coral Mn/Ca‐Based Wind Reconstructions at Kiritimati Island and Butaritari Atoll - Sayani et al, 2021
Global surface temperatures during the twentieth century are characterized by multidecadal periods of accelerated or reduced warming, which are thought to be driven by Pacific decadal variability, specifically changes in trade‐wind strength. However, the relationship between trade‐wind strength and global surface warming remains poorly constrained due to the scarcity of instrumental wind observations. Here, we explore the utility of the novel coral Mn/Ca‐wind proxy at Butaritari (3°N, 173°E) and Kiritimati (2°N, 157.5°W) islands in the tropical Pacific. Coral Mn/Ca records from both sites track WWEs, albeit with some intercolony variability in the magnitude and timing of the signal. Our results suggest that Mn/Ca records from multiple coral colonies and sites are needed to generate robust coral‐based wind reconstructions.
The Iso2k database: a global compilation of paleo-δ18O and δ2H records to aid understanding of Common Era climate - Konecky et al., 2020
Reconstructions of global hydroclimate during the Common Era (CE; the past ∼2000 years) are important for providing context for current and future global environmental change. Stable isotope ratios in water are quantitative indicators of hydroclimate on regional to global scales, and these signals are encoded in a wide range of natural geologic archives. The Iso2k database is a global compilation of 759 previously stable oxygen (δ18O) or hydrogen (δ2H) records spanning the Common Era with a comprehensive set of metadata, which will assist both experts and nonexperts in the interpretation of each record and in data synthesis
Intercolony δ18O and Sr/Ca variability among Porites spp. corals at Palmyra Atoll - Sayani et al, 2019
Cores from living corals are routinely used to extend instrumental temperature and hydrology reconstructions across recent decades to centuries in data-scarce regions of the tropics. Cores from fossil corals can be used to extend such records even further back into the past, with the key assumption that corals growing on the same reef respond to climate in the exact same way. Here we investigate the reproducibility of two commonly used coral proxies at Palmyra Atoll, quantify potential errors in coral-based climate reconstructions from fossil corals, and provide solutions for reducing these uncertainties.
Enhanced El Niño‐Southern Oscillation variability in recent decades - Grothe et al., 2019
The El Niño/Southern Oscillation (ENSO) is the main source of year-to-year variability in the tropical Pacific and has profound impacts on temperature and rainfall patterns across the planet. Climate models suggest ENSO activity may be changing due to human activity, however, several centuries of records are needed to detect any changes in ENSO. This study provides an updated record of ENSO variability over the last 7,000yrs, which shows a decrease in ENSO variability from 3,000 to 5,000 years ago, and an increase in ENSO strength since the pre-industrial.
Porites coral response to an oceano-graphic and human impact gradient in the Line Islands - Carilli et al, 2017
Rising ocean temperatures are expected to drive mass coral bleaching and mortality events over the next few decades. However, not all coral reefs respond to heat stress in the same way. This study examines the relationship between different oceanographic conditions, local human activity, and the resilience of coral reefs to heat stress across the Line Islands.