I grew up in Tucson, Arizona, watching monsoon thunderstorms sweep across the Tucson basin every summer. This childhood experience prompted me to pursue meteorology until an interdisciplinary environmental science program at Stanford made me realize that climate – specifically paleoclimate and how past climate changes have affected humans – is where my interests lie.
Now, my research explores the dynamical mechanisms of the North American monsoon over the Holocene (last 10,000 years). The North American monsoon delivers half of our annual precipitation, but it is currently a feature of Southwest hydroclimate that is not well reproduced in global climate models. Thus, we do not know if we should prepare for major changes in the monsoon as climate changes – what if it fails, as it did in the summer of 2009 when we got only a few weeks of rain, for a number of years in a row? What does that mean for water managers and residents of the Southwest?
With those questions in mind, I am reconstructing the range of monsoon variability on a variety of timescales (interannual to millennial). I use lake sediments and cave speleothems to achieve this. Lakes respond to changes in hydrologic balance in a variety of ways (lake level, chemistry, etc), and isotopes in cave speleothems can be used to determine the winter to summer rain balance to the cave site over short (10yr) to long (100,000yr) timescales.
Furthermore, we do not yet fully understand the response of the monsoon to changes in forcings, such as sea surface temperatures of nearby ocean basins, atmospheric conditions, El Niño, or changes in radiative forcing (increased solar insolation in the past, or increased greenhouse gas concentrations in the present). Thus, by targeting time periods in the past where we know these conditions were different than they are today, we can hope to develop more reliable projections of summer rain in the coming years to decades as these forcings change. Understanding the variability inherent in the monsoon system is critical to preparing for future changes in water availability in southern Arizona and Mexico.
Another project I am currently undertaking is designed to understand speleothems as “sensors” of climate. In many monsoon regions of the world, oxygen isotopes in speleothems are taken to represent the monsoon strength over longer timescales. However, in the desert Southwest, we get two pulses of rain each year, one during the winter and one during the summer. This complicates matters somewhat. Therefore, I am monitoring a number of Southern Arizona caves monthly to determine how calcite formation and dripwater isotope geochemistry relate to interannual climate variability. This, in conjunction with simple hydrological flow modeling, will hopefully help clarify what specific geochemical changes in speleothems signify in terms of climatic change over the past few thousand years.
I am also increasingly interested in science communication. Recent public controversy over the email hack of the Climate Research Unit at the University of East Anglia has illustrated that there exists a gap between climate science and the public’s understanding thereof. I am working with a few other students here to develop better methods and avenues of communication with the public, in the hopes of avoiding miscommunications as seem to happen all the time. I hope to combine these interests during my tenure in graduate school and in the future.