The Past is the Key to the Future

Peter Puleo

Peter Puleo

As a researcher of past climates on Earth, I often find myself thinking of the past as holding the key to the future. There were many periods in Earth’s history that were warmer than the present. As a scientist today, I can look at these older, warmer periods in Earth’s history and use them as analogs for future global warming. Although this method does not perfectly reflect the climates we experience today or will experience in the future, studying these time periods greatly improves our understanding of how and why the climate has changed in the past, which we can reference in the future. As I thought about my trajectory as a student and scientist to craft this narrative, I realized this principle of the past being the key to the future held true there too. My life experiences largely sum up who I am as a scientist now and, most likely, who I will be in the future.

As a young kid growing up in a small town in Wisconsin, I was fortunate to have open access to nature. I remember filling my pockets with dirt from the yard (my mom was not happy about that…) and starting a rock collection that I still have to this day. As I grew older, my interests in the natural world drew me towards science broadly as I began taking science courses. At my small high school, there were no offerings of courses in either Earth or Environmental Sciences, and unfortunately, summer programs and opportunities to learn more about STEM fields were few and far between. Thankfully, I was able to take courses in physics, chemistry, and math, which I enjoyed, but it was not until I began my undergraduate studies in college that my passions for nature and science collided.

Although I discovered my passion for climate study early in my undergraduate studies, my transition into college was not without hardships.

One of the very first courses I took in my first year at Northwestern University was a course on climate change. It was in this semester that I learned about how the global climate is changing drastically in recent years due to the combustion of fossil fuels. Furthermore, I began to appreciate that everyone on this planet experiences negative impacts and repercussions from these sudden changes in climate, with the poorest countries unfairly facing the greatest hardships. We read the book Field Notes from a Catastrophe by Elizabeth Kolbert which described rising sea levels, temperatures, droughts, and floods, all of which drew me towards understanding the complex processes underlying global climate change. This book remains one of my favorite books to this day, and I highly recommend it to anyone interested in stories and climate change. As I worked through the semester, I quickly realized that climate study and Earth science was for me since it would allow me to take part in creating new scientific knowledge, conduct my work in nature, promote education of global climate change, and make an impact on this planet and the people in it.

Although I discovered my passion for climate study early in my undergraduate studies, my transition into college was not without hardships. I struggled greatly in my first year with introductory STEM courses taught at a rigorous pace. Subjects that once felt natural to me in high school, like math and chemistry, suddenly felt out of my reach. By the end of my first year, my grades were not where I wanted them, and my motivation was dwindling.

As a first-generation STEM student, I struggled with asking for help and developing good study habits. Fortunately, I was able to make meaningful connections with older students and reach out to professors and teaching assistants in office hours for advice and studying tips. These choices helped me develop the skills I needed to succeed as a student in STEM and pass my math and chemistry classes.

At the end of my first year, I found myself on a summer trip to Colorado and Utah as part of a geology field camp after taking a course on sedimentology and stratigraphy. In terms of field gear and experience, I had none; all I had was excitement for conducting my first real field work. After my mom and I scraped together some money for the essential items, I left for the field camp and ended up having one of the most pivotal experiences of my life. There were many memorable moments on that trip: making new friends, visiting places I had never been, seeing amazing rock formations, developing observational skills, taking field notes, and camping. It was my first glimpse into being an Earth scientist, and boy was I hooked.

In my second year of college, I realized I wanted to get involved in more hands-on research. I reached out to Dr. Beddows – my climate change seminar professor – for advice. She shared a list of labs that were looking for undergraduate research students, and one caught my eye immediately: Dr. Yarrow Axford’s Quaternary Sediment Laboratory. The Axford lab’s research is focused on tracking changes in lake environments and climates over time through the collection of sediment cores. Sediment cores are essentially tubes of mud taken from the bottom of lakes that can be collected using a system of ropes, pulleys, weights, and PVC tubes off the side of a boat. We lower the tube into the water and raise and lower a weight onto it to hammer it into the sediment. Suction keeps the sediment in the tube when we pull it up from the lake bottom – like when you put your thumb over the end of a straw and it stays full of water. This work seemed like the perfect combination of field work, lab work, and relevance to society – and it turned out it was.

The combination of collecting important samples and spending time with colleagues camping, cooking, flying in helicopters, laughing, and being bitten by mosquitos made this trip unforgettable.

Soon after joining the lab, I was working with Dr. Axford, graduate students, and other undergraduates on research projects. In working with them and learning about how Earth science is conducted day-by-day, I learned a lot about how to do this kind of lab work, use the scientific process effectively, and think like a scientist. After a year and a half of working in the lab and contributing to other projects, I wanted to collect samples of my own for a more independent project. I got approval to go to Wisconsin with members of my lab group where we collected sediment cores from Geneva Lake, located on the southern border of Wisconsin. I analyzed this data and found some interesting results which I ended up writing my thesis about and later publishing.

Soon after this work, I was asked to join Dr. Axford’s team on a month-long field campaign of camping and sediment coring in southern Greenland. I will never forget that day I woke up and saw the email inviting me on the trip. I jumped up and down with joy and called my mom to share the news that I was a part of a team that was making a difference in climate research. I was so overjoyed for the opportunity and also very thankful for the department, Dr. Beddows, and Dr. Axford for dedicating time and money to get adequate equipment and training for me.

The combination of collecting important samples and spending time with colleagues camping, cooking, flying in helicopters, laughing, and being bitten by mosquitos made this trip unforgettable. From the samples collected on this trip, we generated data that informed us of how mountain glaciers and temperatures changed over the past 10,000 years in the region. Besides the sense of accomplishment and fun of conducting interesting research, I made four life-long friends and colleagues on that trip.

In my last year of college, I decided to apply to graduate schools. My experiences with research had been incredibly rewarding and I wanted to continue conducting research in the field of Earth Science., During a discussion with Professor Axford late in the application process, I realized that staying at Northwestern for my graduate studies was an option for me. I not only loved how the research I was conducting contributed to our understanding of how climates changed in the past and how they might change in the future, but also working beside my current colleagues and mentors. It felt like home in the Axford lab. So, I applied to Northwestern University’s Earth and Planetary Sciences graduate program. I, was accepted and chose to stay here and continue my work on climate studies. I am currently reconstructing past climate using the stable oxygen isotope chemistry of bug parts found in sediment cores I collected from Greenland with my colleagues. This chemical ratio is driven by changes in climate and precipitation, making it an extremely useful chemical proxy for paleoclimate reconstruction. I am excited to return for more samples in the future and to continue sharing my knowledge of climate change with others.

Each of the experiences I shared here exceedingly influenced my career trajectory and make up who I am as a scientist today. I would argue that my past has been the key to my present and future. Each experience led to the next, but not always easily or straightforwardly.

One common theme through each of these experiences was unwavering support from those around me. My mentors. My professors. My lab mates. Without their support and guidance, I would not be where I am today. And for that, I will forever be grateful. I cannot wait to be able to be a mentor for students in the future because I know how large of an impact mentorship and guidance can make as a recipient of great guidance in my past.