Research focus

Climate change will transform the natural environment over the coming decades. Increasingly frequent and severe heat waves, droughts, and floods are likely to threaten human life and disrupt economic activity across the planet, while sea-level rise is likely to present a serious long-term threat to the world's coastal cities. My research broadly aims to improve our understanding of the interactions between climate and human society, to identify potential impacts from climate change, and to study ways of enhancing our climate resiliency in the 21st century.

Current projects

Climate change and aviation

Aircraft takeoff performance is strongly dependent on temperature. As air temperature rises, air density declines, meaning that a wing produces less lift at a given speed. This requires that takeoff speeds be higher on hotter days; for a given airport and aircraft type, there is a threshold above which the airplane cannot takeoff at its maximum takeoff weight and must be weight restricted. We're investigating how the frequency of weight restriction may increase in the future, and what economic impact this may have on the airline industry.

This work has received coverage in over 500 media outlets worldwide, including The New York Times, The Washington Post, Science, The Guardian, Phys.org, Gizmodo, and Environmental Research Web.

Ecological impacts of rising temperatures

Many natural systems are strongly dependent on temperature thresholds. As summers become hotter and winter cold becomes less frequent, ecosystems may experience signficant change.

The Southern Pine Beetle is a well-known threat to pine forests. In recent years, the beetle has been observed in New Jersey and southern parts of New York and Connecticut. Prior work has found that the beetle's spread is constrained by the occurance of cold temperatures and that as climate change has made cold events less likely the beetle has moved north. In our work, we use a bark temperature model and the latest suite of climate models to make the first projection of the time of emergence of a climate favorable to the Southern Pine Beetle in the Northeast United States.

Extreme temperatures and heat stress

As climate change progresses, heat waves are projected to become more frequent, longer lasting, and more severe. Extreme temperatures are already the number one weather-related killer in the US, and as these events become more common, their impacts will increase.

Heat stress in humans depends not only on the temperature but also on the humidity. The hottest regions are not necessesarily the most dangerous; the body is remarkably capable of cooling itself as long as the humidity is low enough to permit the evaporation of sweat. However, some of the most densely populated parts of the world can be both hot and humid, presenting a major risk. Recent heat waves have killed tens of thousands of people, caused infrastructure damage and crop failure, and dramatically increased energy demand. Our work has shown that in the coming decades, without rapid emissions reductions, hundreds of millions of people annually could be exposed to levels of heat stress that approach the limits of human tolerance. We aim to identify the most at-risk regions for heat stress, and to understand the dynamics that drive the most extreme events.

This work has been reported in National Geographic, Science News, and Climate Central.

Amplified warming and soil-moisture feedbacks

It is projected that extreme temperatures will generally increase faster than mean temperatures in some parts of the world. We show that in certain regions, most notably central Europe, this warming amplification is driven by strong seasonal differences in warming rates, with temperatures rising fastest during the already-hot summer months. In turn, we find that this amplified warming is linked to strengthening land-surface feedbacks - dry soil allowing for enhansed warming of the air. This finding has implications for future heat risk in Europe, a region where heat waves have caused significant mortality in recent years. It also suggests that improving our understanding of land-surface processes is essential to better modeling future extreme temperature events.

Past projects

Machine learning for improved radar-indicated tornado warnings (2013)

I worked with Dr. Doug Downey at Northwestern University to develop a machine learning system to detect unique tornado signatures in Doppler radar data. The vast majority of tornado warnings are issued due to radar-detected rotation within a severe thunderstorm. However, about 75-80% of tornado warnings are false alarms -- that is, no tornado touches down in the warning area. We found that our machine learning system was able to reduce the tornado warning false alarm rate by 5-10%.

Effects of cathode surface geometry on electrolysis efficiency in microgravity (2011)

I co-founded an undergraduate team at Northwestern to enter the NASA Reduced Gravity Student Flight Opportunities Program with the goal of designing an experiment to be flown on NASA's microgravity aircraft. Our project investigating the effect of surface geometry on electrolysis efficiency was accepted, and we flew the experiment in microgravity in the summer of 2011. More information about our team and our project can be found on our website.