The Cooperative Institute for Climate, Ocean, and Ecosystem Studies

My name is Esmeralda Chavelas and I am a marine biology major at UCSD. This summer I had the pleasure of working with grad student Greta Shum and Dr. Abigail Swann on modeling nearly enclosed bays as oases of life during Snowball Earth.

Snowball Earth occurred roughly around 640 mya during the Neoproterozoic Era in which a dramatic increase in volcanic activity and greenhouse gases caused global glaciation. So, how was photosynthetic life able to survive through such harsh conditions? In order to answer this question, a snowball earth environment was simulated using Python and the model CESM. We used the present continental configuration and set the solar radiation to 91% and CO2 levels to 100 ppm. A total of 15 different experiments with varying surface albedo and CO2 concentrations were done yearly for 20 years of the model.

My part in this project was to analyze the output from the 15 experiments to examine the differences between the spatial pattern of sea ice response to reduced land surface albedo and increased CO2 levels. I was able to create figures from that data and conclude that the Red, Mediterranean, and Persian Seas would be my area of interest. After creating more figures, we discovered that the Mediterranean Sea ice got thinner while the Red and Persian Seas increased in sea ice thickness as surface albedo was decreased. We then hypothesized that the Hadley cell branch shifts northward which results in warmer air, more sublimation, and thinner ice in the North. In addition, we took a closer look at the annual mean for surface temperature, humidity, and P-E (precipitation- evaporation) for our area of interest. It was concluded that the Red Sea experiences a decrease in temperature, an increase in relative humidity, and an increase in precipitation while the Mediterranean experiences an increase in surface temperature, a decrease in humidity, and a decrease in precipitation.

In conclusion, our understanding of habitability is broadened because we now know that not only is land surface temperature important in the possibility of a refugium but also atmospheric circulation, surface albedo, and continental configuration. Additionally, we can better understand how life was able to diversify immensely after Snowball Earth.

This was such a memorable internship in which I gained a variety of skills and learned from so many bright grad students in the Department of Atmospheric Sciences and the School of Oceanography. This experience has definitely given me the knowledge and confidence I need to succeed in my future endeavors as a scientist.

Project introduction

Research poster