Aidan Crawford ’22
ESE Primary, EPS Secondary
(Summer 2020) After graduating with the class of 2020, I have been working as a post-graduate fellow with the Keith Group here at SEAS to build upon the research I started for my senior thesis. The project's aim is to study the potential for global marine cloud brightening to affect sub-seasonal weather patterns. The study uses a modified version of the Community Earth System Model (CESM) to study the response in 500 mb geopotential height fields to mesoscale changes in cloud droplet number concentration in high cloud fraction areas above key ocean basins. The goal of the study is to determine whether cloud seeding technology could potentially be used to manipulate planetary Rossby waves and therefore affect sub-seasonal weather patterns. I am working on this project primarily with David Keith (SEAS/HKS) and Marissa Saenger (Harvard '19).
(Summer 2019) Aidan Crawford (Environmental Engineering S.B. with an EPS Secondary) spent the summer working on a solar geoengineering research program as a part of the Keith Group at Harvard SEAS. His project examined the potential effect of a Marine Cloud Brightening (MCB) geoengineering scheme on various natural climate mechanisms. In particular, he focused on the ability of a general or targeted MCB deployment to alter the tracks of tropical cyclones before they make landfall. The project utilized NCAR's Community Earth System Model (CESM) to simulate climate response.
Will Flanagan ’20
(Summer 2019) While taking Dr. Brad Lipovsky’s course in Glaciology last fall, I used seismological tools and methods to try to measure ice sheet thickness. The project involved downloading and analyzing data from existing seismic stations in Antarctica, and it introduced me to the intriguing field of glacier seismology. I quickly decided to dig deeper by doing summer research with Brad and Professor Marine Denolle. We soon began to look into potential glaciers for a project in which we would gather original data to attempt to couple seismology to subglacial hydrology.
In July, I traveled with Brad and Seth Olinger (G2) to Valais, Switzerland, where we deployed small, three-component Raspberry Shake seismometers on three different glaciers over the course of a week. On Gorner Glacier and Rhône Glacier (the first and last glaciers we visited), we deployed instruments overnight. Conversely, on the pancake-shaped Glacier de la Plaine Morte, we visited two different sites — spending the first day near a human-engineered channel and the second near the large terminus — and conducted multiple shorter deployments for each instrument on both days (and stayed at a cool alpine hut in between!). We generally deployed the seismometers near features such as moulins, superglacial rivers, and termini. Additionally, we flew a drone at all sites except Rhône Glacier (where flying is prohibited) to construct digital elevation models (DEMs) of the glaciers in their current forms, which have diverged drastically from even the most recent Google imagery.
Since returning to Cambridge, I have been processing the Swiss data: plotting spectrograms, relating the results to weather and hydrological features, and cross-correlating signals to analyze various events. Many thanks to Brad, Marine, and Seth, for their tremendous guidance and dedication all summer; to EPS and HUCE (and their wonderful staff members) for funding and supporting this research adventure; to Professor Fabian Walter and his group at ETH Zürich, for their collaboration at Plaine Morte and for providing us with mountaineering gear; and to Dr. Adam Soule of WHOI, for lending us his awesome drone and for helping with the DEMs.
Caleb Fried ’22
(Summer 2020) The question of whether or not the Little Ice Age was a globally consistent event or just regional cooling has been a source of a lot of debate in the paleoclimate community. This past summer (2020), I worked remotely with Peter Huybers to develop a new method of looking at the spatial homogeneity of cooling during the Little Ice Age. Using modern instrumental data, I found that by representing climate spatially as a series of binary variables (the climate in an area is either above the local average or below it), the spatial homogeneity of the global climate has an extremely close relationship with the global average temperature. I then developed this statistical framework further, using artificially sparse and noisy instrumental data to verify the technique’s usefulness for proxy data, which is much sparser and noisier than the original instrumental dataset. We applied this technique to a database of many different proxy types (data from tree rings, sediments, ice cores, and more), developing a way to use multiple proxy types to calculate the spatial homogeneity of the climate without the need for rescaling. Working on this project over the summer gave me the chance to learn a lot more about statistical methods and signal processing, and the results we found seem to suggest that the Little Ice Age actually was a globally consistent climate event!
(Fall 2019) I worked under professor Peter Huybers to try to develop new methods of reconstructing solar variability, with the end goal of supplementing our understanding of the climate forcings that contributed to the Little Ice Age and Medieval Warm Period. I spent the semester investigating the potential of reconstructing past solar variability using solarization- the sunlight-induced photochemical alteration of the absorption spectrum of any silicate glass. For this purpose, I collected old stained glass window samples from a local church and cut and polished them to compare glass that has been exposed to sunlight to glass that has remained mostly unexposed over its lifetime (hidden under plaster moldings or the shadow of the building). I analyzed these samples using visible and near-infrared spectroscopy to compare the concentration of Fe2+ in the samples, and thus the extent that the solarization reaction had progressed in each part of the glass. In addition to designing and setting up the experiments, I learned how to modify my instruments and setups to perform transmission spectroscopy measurements on glass surfaces rather than liquid samples.
Maddie Goldberg ’21
(Summer 2020) This past summer (2020), I started work on my senior thesis! I worked remotely for the first couple of months, which gave me a chance to delve into the literature on my topic--the chemical mechanism involved in pyrite oxidation--and to familiarize myself with some of the mechanistic questions that remain. I also started framing and researching an idea that I developed with my advisors, Dave Johnston and Andy Knoll: a non-lab, investigative portion of my thesis devoted to the environmental and human impacts of the chemical mechanism I'm studying. In that section, I plan to focus on the pollution caused by pyrite oxidation (known as acid mine drainage) through the lenses of environmental history and environmental justice. And by late summer, with safety precautions, I was able to get back into the lab! Working primarily with post-doc Jordon Hemingway, I've been getting some of my first experiments up and running. Most recently, I've started experiments to study the oxygen isotope systematics of sulfite-water and thiosulfate-water equilibria at various pH values. Next, I'm gearing up to start a series of pyrite batch experiments, in which I aim to determine how the source of sulfate oxygen (sulfate is a product of pyrite oxidation) varies according to reaction conditions. The goal of the lab portion of my thesis, as I currently see it, is to refine our understanding of the precise pyrite oxidation mechanism, such that prevention and remediation techniques for acid mine drainage could become more targeted and effective. I've loved working on this project so far, and I'm so grateful to my advisors, the Johnston group, and the EPS department for helping me have both a safe and fulfilling summer research experience, even under such unusual circumstances.
(Fall 2019) This semester, I continued as a research assistant in Dave Johnston’s isotope geochemistry lab. I worked with Jordon Hemingway to set up and initiate a series of experiments aimed at examining the rate and mechanism of pyrite oxidation under various conditions. Pyrite (FeS2), often known as “fool’s gold,” is a valuable mineral when it comes to investigating Earth’s environmental conditions, especially on an ancient planet. Because pyrite is so readily oxidized, its presence or absence in the rock record can lend insight into the oxidizing capacity of the early Earth. And this is only one dimension in which pyrite has proved a compelling mineral to study; Jordon’s measurement of the oxidation products’ isotopic composition (particularly an unexpected ∆17O result) has raised a number of intriguing questions about the precise mechanism by which pyrite is oxidized--and suggests that the process may actually be quite different from what is typically assumed.
The series of experiments that I started this semester with Jordon will hopefully help to clarify that mechanism. We are using a chemostat setup, which allows us to monitor and toggle various chemical parameters while the reaction in question--oxidation of pyrite--is running. A few of the variables that we hope to investigate are pH (our input solution has thus far been buffered around 7), dissolved oxygen content of the input reservoir, flow rate of the input reservoir, and the presence of hydrogen peroxide. All of these parameters allow us to imitate various environmental conditions, and, alongside isotope analysis, can lend insight into the role of those parameters in the reaction mechanism. To be sure, getting the chemostat framework to run smoothly was a bit of a challenge!
The semester has provided an excellent lesson in the intricacies of experimental design- and the fact that it’s okay to diverge from the original plan when something isn’t working! For instance, we discovered that what we thought was a collection of pyrite grains of a single size fraction- we’d sieved it--contained a good deal of smaller grains, possibly of a different mineral. It took many more rounds of sieving, as well as a heavy liquid separation, to achieve the correct size fraction. Trying out different methods and thoughtfully adjusting our approach was an exciting aspect of the lab work for me--it meant I got to engage firsthand in the scientific process, and I learned new skills, like conducting methylene iodide separation or wrangling an anoxic glove bag, as a result. I’m looking forward to continuing these experiments in the coming semester!
(Spring 2019) This semester, I've been working with Jordon Hemingway in the Johnston lab on a series of experiments related to pyrite oxidation under a number of conditions. So far, the experiments have involved oxic conditions--namely, rate calculations at varying pH. We also produced a calibration curve so that we can reliably use the spectrophotometer as a measure of sulfate production; this will likewise let us determine the reaction rate. Next, we will do these experiments in a chemostat setup, which allows for the maintenance of extremely constant chemical conditions, like pH and dissolved oxygen concentration. I haven't done much lab work before, so most of the steps involved are unfamiliar to me. As a result, this has been an excellent learning process, and I feel far more capable in a lab setting than I did at the beginning of the semester.
Hillman Hollister ’19
(Spring 2019) This semester, I collaborated with John Shaw’s group on a project focusing on the geology of the Andes Mountains. By interpreting this geology, we hoped to inform the search for energy resources in the subsurface. We began at a high level, reading papers and learning about how these mountains formed, with a specific interest in the Andean orocline–the bend in the mountain chain. I then began to collect high resolution satellite imagery of regions that we identified as important. I learned to stitch together the images using GIS software, and then layer different types of images on top of each other to create a 3D, true color representation of local geological formations. This new imagery will be used to improve existing seismic reflection data of the area and will likely be used to inform upcoming field expeditions.
Jason Jorge '23
EPS-Astrophysics Joint Concentration
Picture caption: Hurricane Bill from the perspective of the Harvard Seismograph Station, including its track, wind speed and pressure, distance to the station, azimuth between Bill and the station, and averaged power in the North/South and East/West directions as a function of time.
(Summer 2020) In summer 2020, I began a research project under the supervision of Professor Miaki Ishii and 1st-year PhD student Thomas Lee on the relationship between hurricanes and seismic noise. The main mechanism through which hurricanes produce detectable seismic signals is wave action, and investigating the effects of the hurricanes’ tracks and intensities on those signals were my main goal. Thus far, I have analyzed around a dozen hurricanes from the last decade and discovered that hurricanes of a particular track produce a particular seismic power signal. My next steps include processing bathymetric data to see its effect on seismic noise and discerning the effects of local weather conditions on seismic noise from that of hurricanes or other coastal storms.
Since quantitative seismic records extend much further back in time than meteorological records, being able to determine the track and intensity of a hurricane through the relationships between seismic noise and hurricanes I have been researching whose meteorological records are either absent or incomplete would allow for a more accurate characterization of ocean storms going further back in time than currently possible. Making the comparison between older ocean storms and modern ocean storms will contribute to the current understanding of the effects of climate change on ocean storm frequency and intensity.
Alison Kim '21
(Summer 2020) Changes in the Earth's rotation rate, as measured by a series of artificial satellites, have been an important component of geophysical studies of modern climate. As polar ice sheets melt, and mass is moved away from the poles toward lower latitudes, the Earth's rotation will slow down (just as a figure skater's rotation will slow if they move their arms outward). However, a major complication in studies of Earth rotation is that the present day changes also have a contribution from ongoing adjustments of the Earth related to the ice age, and that contribution, in turn, is dependent on the Earth's internal structure -- in particular, the viscosity of the Earth's mantle. Numerical "forward" calculations have shown that predictions of the changes in Earth rotation due to the ice age are most sensitive to viscosity in the deep mantle of the Earth, but despite 40 years of study the actual 3-D sensitivity to viscosity of these predictions is unknown, largely because traditional methods of computing the 3D geometry of the sensitivity are computationally impractical. I am working on overcoming this limitation by using "inverse" rather than forward methods -- that is, methods that begin with observations and work backward to constrain sensitivity. One extremely efficient technique for computing the sensitivity is the so-called "adjoint method." In my research during the summer 2020, I used the method to map out the 3-D sensitivity to viscosity of Earth’s rotation changes due to the ice age. Once complete, this will be a major step in improving estimates of the ice age signal and, as a result, reducing uncertainties in estimates of modern polar ice melt.
Elida Kocharian ’21
(Spring 2019) This spring, I’ve been working with Dr. Jenan Kharbush as a research assistant in the Pearson lab on a project that analyzes the fractionation of nitrogen isotopes in photosynthetic microorganisms, specifically diatoms and cyanobacteria. I’ve been happy to work as a primary caretaker of the lab’s critters, including growing, transferring, and harvesting diatom and cyanobacteria cultures; developing cryopreservation methods to maintain the cultures; developing growth curves for each culture based on optical density and cell count; and measuring nitrogen and chlorophyll concentrations at different growth stages with nitrogen/chlorophyll assays. During my time in the lab, I’ve learned how to grow and analyze cultures, how to mix and create different kinds of media, how to perform various procedures including isotope assays, and how to develop and follow a scientific procedure in an experiment—along with countless other valuable scientific skills that I’m immensely grateful to have learned in a hands-on, active environment. Here I am transferring a cyanobacteria culture in the sterile hood! (photo creds to Jenan)
(Fall 2019) Every year, 8 million metric tons of plastic is dumped into the ocean. The vast majority of this waste are microplastics, 5mm or smaller plastic particles that float throughout the water column and accumulate at the surface. The effects of plastic accumulation on marine life and ecosystems has been an area of increasing research--but is it possible that the buildup of plastic at the surface ocean effects the greater oceanic hydrological cycle? This semester, I've been exploring this theoretical question experimentally in the lab by designing and building a toy ocean model to test whether agglomerations of microplastics at the surface dampen ocean evaporation. The experimental method I developed involves measuring changes in mass, surface temperature, and relative humidity of an ocean-simulating tub under different weather conditions by varying wind speed and solar radiation and under different amounts of microplastics using a precision balance, anemometer, and IR camera. The majority of my work this semester has been devoted to building, piloting, and fine-tuning the experimental setup, but our preliminary results suggest a negative correlation between the amount of plastic in the system and the evaporation rate, meaning plastic may be slowing ocean evaporation in our small-scale approximation. Future work will develop these initial results and we hope to include potential findings in larger, global-scale ocean hydrological models that don't currently account for the effects of plastics on circulation.
Thomas Lee ’19
(Summer 2019) This summer, I spent time working in EPS with Professor Miaki Ishii on both building further upon my thesis work, and wrapping up a project on time corrections for analog seismograms. My thesis work was on imaging the subsurface of Kīlauea, Hawai`i during the volcanic eruption of summer 2018 using ambient seismic noise, this work has since expanded to investigate the volcanic tremor detected in the seismic noise and ways to track it. As work progresses, this work could bring great benefit to both the volcano-monitoring and volcanic-hazard communities. The time correction project involved using the symmetry present in seismic noise correlation functions to generate relative time corrections between stations. This method was applied to digitized paper seismograms, and opens up more opportunities for the use of such legacy data.
Maya Levine '22
Picture caption: A beautiful (but contaminated!) lake near Joint Base, Cape Cod
(Summer 2020) I spent last summer (2020) doing remote research with the Sunderland Lab where I was helping to conduct a water quality assessment of perfluorooctane sulfonate (or PFOS )-contaminated groundwater near our field site on Joint Base, Cape Cod. Using previously collected water samples on and around the military base, we were trying to understand the fate and transport of PFOS from the contaminated site to downstream groundwater and drinking water sources. We then did data analysis in order to incorporate that information into a risk analysis for impacted communities. I then began to explore census data, using demographic and geographic data sets alongside the geographical PFOS information. This project is continuing with the hopes that we can come up with a comprehensive risk assessment to understand the health risks of PFAS-contaminated water to various at-risk populations.
David Ma '22
Applied Math Primary
(Summer 2020) The ocean is one of our planet's most tenacious defense mechanisms against rapid changes in climate; yet over the past few years, there have been many publications suggesting that oxygen in the ocean (and especially the deep ocean) is being depleted at an unprecedented and alarming rate. Most of the analyses, however, use data gathered by ships from various countries over the last half-century, and as such, we need to account for differences that may exist between ships. Distinct ways of measuring, recording, and even rounding measurements could constitute systematic offsets which could in turn generate artificial trends. My remote project during the past summer (2020) was to first, determine if such offsets were present, and then to quantify their impact. Under the guidance of Professor Huybers and Duo Chan, I found offsets between ships originating from over twenty nations and at a magnitude consistent with the decreases in oxygen reported in other studies. Building on these exciting results, I am now working to remove these offsets and determine what changes are actually happening in the deep ocean.
Ethan Manninen ’21
(Summer 2020) This past summer (2020) I worked in the Wofsy Group analyzing ATom data. Professor Steven Wofsy, Dr. Yenny Gonzales, and Professor Roisin Commane and I are interested in N2O source processes as observed by ATom. N2O is an important greenhouse gas, and depletes stratospheric ozone. I took several angles on this project; I clustered the ATom observations based on trace gasses, estimated N2O fluxes, and read a lot of literature. I learned a great deal this summer. My coding skills improved, and more importantly, I began to take more ownership of atmospheric chemistry science questions. It was a little strange working remotely, but on the other hand I could bring my dogs to work every day and hike in the Sonoran desert as a break. This work will culminate in my thesis this spring!
(Summer 2019) I spent this summer working in the Wofsy group on data from the ATom campaign. My project meandered a fair bit over the course of two months, before I settled on a plume of carbon monoxide that is flowing off the west coast of Africa into the air above the Atlantic. Specifically, I am interested in the different sources of CO, and how the trace gasses associated with the emissions from those sources affect hydroxyl chemistry. OH is crucial to the atmosphere's ability to remove methane and other pollutants, and understanding how human emissions are changing atmospheric OH is an important and challenging problem.
I have deeply enjoyed learning technical skills including how to use the Harvard Odyssey Computing Cluster, as well as how to interact with data structures I had not seen before outside of EPS research. Perhaps more important has been my growth in terms of the research mindset: being flexible, and knowing when to ask for help. The best part of the summer has definitely been meeting all sorts of wonderful people, both at Harvard and in the broader EPS community.
Tyler Moulton ’20
(Fall 2019) In the fall 2019 semester, I started a research project under the supervision of Professor Robin Wordsworth and a 3rd-year PhD student in his group, Kaitlyn Loftus. My project’s overall goal is to examine and model the atmospheric evolution of carbon dioxide and water on planets in the habitable zones of M dwarfs. M dwarf stars are less luminous than our sun but make up 80% of the stars in the Milky Way and burn for much, much longer than our own sun—making them extremely interesting candidates for having potentially Earth-like or habitable planets. To examine and model this evolution, I have been working with Kaitlyn and Professor Wordsworth to construct a model to examine how a planet distributes a set input amount of carbon and water between its ocean and atmosphere. Along the way, I’ve also reviewed literature enabling me to fine tune my model and explore how different stellar and planetary parameters affect the atmospheric evolution of carbon dioxide. Moving forward, I’m hoping to improve this model and see whether I can incorporate other earth and planetary science softwares and theory so as to create a rigorous model for how planetary habitability can be maintained around M dwarf stars!
Ana Luiza Nicolae '22
EPS Primary: Special Concentration
Picture caption: Jessica Don G6 with Sage and Ana Luiza Nicolae ’22 share a Zoom moment during summer research.
(Summer 2020) When the pandemic struck, I didn’t think I could have a great summer at all. However, I reached out to my (first ever) geology course professor, John Shaw, who introduced me to the world of structural geology. He very quickly shared with me what projects his group was currently working on, showing me what kind of work each would entail for the summer (2020). I ended up choosing to work alongside Jessica Don, a sixth-year PhD student in the group, and the most awesome dog on Earth, her Sage! I received tremendous support in getting the appropriate software going and started getting familiar with the geologic structure of the Mid-channel blind-thrust fault, located just offshore Santa Barbara. Having to map the evolution of this structure along its length (strike) allowed me to learn three things.
First, what sort of data and data limitations structural geologists commonly deal with. Second, how to use the most advanced modelling tools (such as Gocad) to trace the evolution of sediment beds with better precision as to their different ages. And third, how this specific structure fits into larger ones, such as the Transverse Ranges and ultimately the strike-slip fault of San Andreas, which allowed me to apply the understanding of the building blocks of tectonics I had learned in class.
Aside from learning so much through building a model of the Mid-channel fault based on available past interpretation, seismic lines, borehole measurements and more, I was able to learn about many more different projects through the weekly meetings with Professor Shaw’s group. These always brought a lot of perspective by visiting how geologic principles apply at different scales, and can be involved in so many areas, from industry, to community models to help reduce seismic hazards, and to theoretical research. I know that this experience, through the support of Jessica, Sage, Professor Shaw and every member of his group, has opened my eyes to a discipline I now wish to pursue!
Jacob Ott ’20
(Fall 2019) This fall term I worked on two projects in the Fu Lab, one planetary in focus and one terrestrial. The planetary project--a study into the ancient magnetic fields of the asteroid Vesta--involved preparation of two meteorite thin sections and analysis on Quantum Diamond Microscope, a state-of-the-art magnetic field imaging instrument. QDM analysis is ongoing but so far it is unclear whether the particular meteorite sections being analyzed have retained substantial magnetic remanence. The terrestrial project is an investigation into the chemistry of impact ejecta deposits in South Africa called "spherule beds." Spherule beds are thought to retain chemical signatures of the Archean crust and mantle. I have analyzed a dozen spherule samples using Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry and have developed a program to aid in processing the large amounts of spectrometry data produced. So far, my data suggests that the spherules which have escaped significant post-deposition alteration do indeed possess some Archean crust and/or mantle components, although specific compositions for these components are yet to be determined.
(Spring 2019) Early this semester in Roger Fu’s paleomagnetics lab, I prepared a meteorite from the asteroid Vesta for analysis under the cutting-edge Quantum Diamond Microscope. The QDM was then used to map the meteorite’s magnetization, which it received while under the influence of Vesta’s ancient dynamo. Preliminary results suggest the magnetization is contained within vein-like features, but the magnetic carrier minerals themselves have been elusive. I am gathering more data now to puzzle this out. I have also assisted in the preparation of zircon samples, the oldest magnetic recorders on Earth. The magnetization of these zircons will tell the latitude of their formation site (paleolatitude) and provide novel constraints on ancient plate tectonic motion.
Robert Powell ’20
(Summer 2019) My research this summer is if focusing on how microwave satellite observations could greatly improve our ability to monitor fuel moisture content, and to predict wildfire risk. The Soil Moisture Active Passive (SMAP) satellite, an L-band microwave satellite mission launched in 2015, provides global retrievals of surface soil moisture (SM) and vegetation water content (VWC) at 9-km resolution. In this study, we will test the added utility of SMAP observations on several recent wildfires, including California’s 2018 Camp Fire. Wildfires are identified using observations from the Moderate resolution Imaging Spectroradiometer (MODIS) burned area product. For each wildfire case study, time series of SMAP-observed SM and VWC in the days preceding the fire will be compared to corresponding time series of weather-based fuel moisture content proxies currently used in wildfire risk predictions. By comparing current prediction models with data from the SMAP instrument, this project aims to assess the potential for improving wildfire predictions with microwave satellite observations.
Beck Saine '22
(Summer 2020) This homemade tablet stylus encapsulates my research experience during summer 2020: the circumstances may have been constricting, but there was still a way to benefit despite the limitations. In the Johnston lab, Beck worked with Anna Waldeck and Dr. Johnston on a number of small projects all related to current research in stable isotope geochemistry. I engaged with the revision process of Haley Olson and Anna’s publication about triple oxygen isotopes in Messinian sulfate evaporites. Along with other undergraduate researchers, I explored various geological applications of stable isotope geochemistry through literature review, reading groups, and attending the virtual Goldschmidt geochemistry conference. With Anna’s help, I made a basic fact-sheet about stable isotope geochemistry and a few relevant applications geared toward other beginning undergraduate researchers. I also gained significant programming knowledge, completing a data science course in R and applying the programming to various geochemical problems.
Vladislav Sevostianov ’19
(Summer 2019) I spent the summer building a drone based photoionization detector (PID) to measure volatile organic compounds (VOCs). I spent much of the summer in the Physics/SEAS Machine Shop where I also received my green certification manufacturing the sensor and performing laboratory testing afterwards. This is all for my senior thesis, which I will be presenting in November, and I also plan on presenting my work at AGU in December afterwards. The instrument I've built currently detects to around 3ppb, and I hope to soon have it at 1ppb detection as I keep evolving my design. The trickiest part is proving to be the electronics, as I am measuring fractions of nano amps, so I am having to quickly learn other skills to help solve the atmospheric measurement problem I set out to solve initially!
Kevin Stephen '20
Applied Mathematics primary
(Summer 2020) This past summer (2020), I extended the research on optimization methods for solar geoengineering that I performed over the past year for my senior thesis. Solar geoengineering defines the set of methods that attempt to mitigate the effects of anthropogenic climate change by modifying the terrestrial response to solar radiation. Although a growing body of literature examines the use of geoengineering to achieve large-scale objectives like global mean temperature reduction, little research has investigated the regional ramifications of geoengineering practices. In my senior thesis, I utilized the output of seasonally and regionally variant geoengineering simulations conducted in the HadCM3L global climate model to analyze the ability of linear optimization methods to modify regional climate objectives. During the summer, I conducted a series of experiments in the higher-resolution CESM climate model to investigate the ability of regionally optimized geoengineering patterns built from a simpler model to predict local effects in a more complex climate system, examining impacts on both mean temperature and precipitation effects and regional climate extremes.
I also examined the impact of these regionally optimized geoengineering patterns on climate extremes by documenting changes and patterns in droughts, heat waves, and precipitation extremes. My paper ultimately demonstrates that although a regionally optimized geoengineering mechanism may mitigate regional impacts in a model setting, it likely would disproportionately harm some land areas and populations more than others when applied to the real world. The inability of optimized forcing patterns to alleviate local rainfall reduction and drought amidst increased model complexity suggests that geoengineering may be unable to reconcile global temperature reduction with locally adverse human-, agricultural- and wildlife-related impacts.
Sophie Webster ’21
(Spring 2019) Over this semester, I've worked on two separate projects with Shelley and Felix, in Ann Pearson’s lab. Shelley is trying to grow archaea under different conditions (both autotrophically and heterotrophically) to eventually analyze their membranes for GDGTs, lipids whose concentrations have been shown to covary with temperature. This could be important for reconstructing paleoclimate using the TEX86 variable (a ratio established from concentrations of different GDGTs). I assisted Shelley by working with the archaea grown on iron, calculating their day-to-day growth with Fe-oxidation assays. Felix is working to understand nitrogen cycling at the PETM (Paleocene-Eocene Thermal Maximum). In the three different sediment cores we are using, there are notable carbon excursions that denote the PETM, and we are wondering if we will notice a similar trend in nitrogen. I have been massing and preparing core samples to run on the EA. This process has been slightly trial and error, as we are trying to find the appropriate mass to deliver a large-enough N peak for analysis. Pictured: Me wrangling New Jersey sediment core samples, massing them and dexterously loading them into tiny tin foil cups.
Kendra Wilkinson ’20
(Summer 2019) "I am working in Professor Mitrovica’s research group with graduate students Marisa Borreggine and Evelyn Powell. The overarching goal of our project is to determine the most likely pathway for the first human migration from Sunda to Sahul. Within the greater project, my focus is determining whether or not one island is visible from another island, a variable also known as inter-island visibility. This variable impacts the probability of human movement from one island to another; greater visibility lowers the risk involved in a potential crossing and consequently heightens the probability of movement. Over the summer, I have been developing a code that will create several maps we will use to determine inter-island visibility and the likelihood of travel from one island to another. This will allow us to evaluate potential pathways between the two major landmasses and brings us one step closer to determining the most likely migration pathway from Sunda to Sahul."
Joseph Winters ’20
(Summer 2019) Past research has reliably found that elevated levels of CO2 (eCO2) cause protein, zinc, and iron reductions in agricultural crops like rice and wheat, but there has been much less research about how eCO2 might affect food sources that are important for pollinators — that is, flowers. Bees depend on pollen protein for larval development, but researchers are worried that, like with cereal grains, eCO2 could bee causing flowers’ pollen protein concentrations to drop. Senior Researcher at the USDA Lew Ziska recently confirmed this was the case for goldenrod, an important source of pollen for bees that overwinter — the apian equivalent of hibernating. So this summer, I joined his lab at the Agricultural Research Service near Washington, DC to find out how eCO2 might affect other flowers. We used growth chambers to grow eight flower species from seeds, half of them in a 400ppm environment and the other half in a 600ppm environment. Then we transplanted them to eight outdoor plots, sealed them off in a mesh enclosure, and placed a bumblebee colony in each plot, allowing the worker bees to collect pollen from each plot’s flowers. Just like the bees, I have spent much of my time hand-collecting flower samples, then dissecting and storing them for later analysis. We also plan to run analyses on each of the eight beehives — we‘re going to flash freeze them in the final days of the experiment so they can be shipped back to Harvard. This fall, my advisor and I will assay the flower samples for protein content, among other things.
In this photo you see me in the bee suit — a vital tool for my research! When provisioning the bees with pollen, you have to remove the hive’s entry box, open the lid, and force pollen pellets through small slits in the top of the box. It’s for their benefit, but they can get pretty angry about the intrusion!
Luann Zerefa '21
Integrative Biology primary; Earth and Planetary Sciences secondary field
(Summer 2020) This past summer (2020), I worked remotely in Stephanie Pierce’s vertebrate paleontology lab under the supervision of postdoc Megan Whitney. I was studying the bone histology of axolotls, which have a primarily aquatic lifestyle, and terrestrial tiger salamanders to look for signals of habitat since amphibians undergo different mechanical strains in aquatic versus terrestrial environments. Using Dragonfly software, I segmented different bone elements of femora across developmental stages from micro-CT scans of samples in the Pierce Lab. Qualitative preliminary results suggest that rather than trabeculae (spongy bone) presenting prominently in our samples, distal and proximal calcified cartilage, which is degraded throughout endochondral ossification, did. This suggests that retaining calcified cartilage may be a potential variable related to relative degrees of terrestrial specialization worth exploring. I will gather more qualitative data this coming semester to explore this observation. This work will be used to support developing a framework for interpreting paleohistology using salamanders as modern analogues for the water-to-land transition.