KrisBy its nature, the study of climate is an interdisciplinary endeavor, necessitating the union of diverse and oftentimes disparate fields. Dr. Kris Karnauskas, new ATOC Assistant Professor and CIRES Fellow, is investigating climate dynamics and impacts, specifically in the tropics, by blurring the lines between oceanography and atmospheric science.

To Karnauskas, oceanography and atmospheric science necessarily overlap and inform one another:

“There is a reason our department at CU is called Atmospheric and Oceanic Sciences. We, [atmospheric scientists and oceanographers], are all looking at different pieces of a coupled system. Whether we are studying the jet stream or an underwater current, we are fundamentally looking at phenomena that affect each other.”

As an undergraduate at the University of Wisconsin-Madison, Karnauskas gained a foundation in the atmospheric side of climate science. Later, his research focus grew to encompass oceanography, as he explains:

“In graduate school at the University of Maryland, my advisor was a climate scientist with a strong focus in tropical oceanography. I found this to be a natural transition; all the equations and physical principles that I learned in the context of the atmosphere translated nicely to the ocean.”

Determined early on to work at the intersection of multiple fields, Karnauskas accepted a position as a climate dynamicist at Woods Hole Oceanographic Institution on Cape Cod immediately following a postdoc at Columbia University. He notes:

“The job at Woods Hole turned out to be a very interesting fit, which significantly broadened by way of thinking. The range of research going on [at Woods Hole] is vast, and my department was focused on making connections across interdisciplinary lines. For example, we worked with paleoclimatologists that reconstruct ‘long’ records of climate variability. My niche was providing the contemporary, mechanistic context [to the study of these ancient climates.]”

Karnauskas is joining the CU ATOC faculty this fall, where he will lead his research group dubbed the Oceans and Climate Lab. The lab will provide Karnauskas with an ideal platform through which to pursue existing and new research avenues, as he notes:

Aridity

Karnauskas’s team found a notable trend towards greater aridity on 73% of the island groups by mid-century; such aridity would translate into freshwater stresses on vulnerable island populations. Credit: Kris Karnauskas.

“I have a range of ongoing projects that will continue while at CU; fortunately, life would never work out such that I would leave [Woods Hole] and all of my old projects would just end. I see many avenues for exploring new topics here as well, given the many national and governmental labs and universities along the Front Range. In the near-term, I will continue focusing on the dynamics and impacts of global climate change, with a special eye towards impacts.”

Among his ongoing projects, Karnauskas is seeking to supplement existing global climate models with evaporative calculations to reveal trends in freshwater stress on islands that are traditionally too small to appear in such models. He explains:

“One issue with the IPCC models is resolution. These models have “pixels” on the scale of a hundred kilometers or so; meaning, if you live on an island that is too small, your homeland doesn’t show up. With just these models, we as a scientific discipline lack the ability to inform, say, French Polynesia of what to expect in terms of the affect of anthropogenic climate change on freshwater resources.

Approximately 18 million individuals live on islands that are precluded from current global models. Through analysis of evaporative demand of 80 island groups, Karnauskas’s team found a notable trend towards greater aridity on 73% of the island groups by mid-century; such aridity would translate into freshwater stresses on vulnerable island populations. Without properly considering evaporation, one would be led to believe the islands are split 50/50 between drying and wetting.

Air travel

Karnauskas's team has found a correlation between global climate change and increased flight times. Credit: Harvepino/Shutterstock.com.

Recently, Karnauskas also received international attention for his Nature Climate Change publication “Coupling between air travel and climate” detailing the impact of climate change on air travel. He notes:

“Normally when you think of climate and air travel, you think of how air travel affects climate. We flipped that around and said that if atmospheric circulation changes, how is that going to affect the global airline industry?”

By analyzing 250,000 flights between Honolulu and LAX, Karnauskas’s team determined that jet stream shifts over the Pacific Ocean due to global climate change may increase net (round-trip) flight times in the future. A press release from Woods Hole effectively summarizes the economic effects of such flight lengthening:

"According to the study, there are approximately 30,000 commercial flights per day in the U.S. If the total round–trip flying time changed by an average of one minute, the amount of time commercial jets would spend in the air would change by approximately 300,000 hours per year. This translates to approximately 1 billion gallons of jet fuel, which is approximately $3 billion in fuel cost, and 10 billion kilograms of CO2 emitted, per year."

For Karnauskas, the next step is to tackle the impressive computational challenge of analyzing global airline routes to determine whether, in aggregate, flight durations are expected to lengthen.

A common link among Karnauskas’s diverse research is his utilization of data from remote sensing techniques. He notes:

Penguins

An August 2015 study by Karnauskas's team found that shifts in trade winds and ocean currents have enlarged the cool, nutrient-rich pool of water that Galapagos Penguins rely on for feeding and breeding, causing a resurgance of the species. Credit: Kris Karnauskas.

“Although I work with models and instrumental observations, more often than not my papers also benefit from satellite data. For example, in a recent paper about how ocean circulation affects the Galapagos penguins, we used a remarkable three-decade long satellite-based record of ocean temperatures to determine how ocean temperatures around the Galapagos Islands are changing [and impacting penguin populations]. I’ve looked at so much data from satellites - from ocean color to scatterometry to land surface temperature - that I’ve come to realize that remote sensing is essential to the study of climate no matter what time scale or phenomena you’re interested in.”

 

As he prepares to begin his faculty career at CU, Karnauskas reflects on the appeal of the Boulder community:

“I’ve always gotten a vibe that this is a community of collaboration, since my first visit to NCAR in 2003. I see myself not just moving to CU-Boulder, but plugging into the whole Boulder [climate] community. I have several good colleagues at NCAR and NOAA. I plan to use my proximity to these labs to strengthen those collaborations, meet new people and explore what new interdisciplinary work can be done here.”

-Written By: Ari Sandberg, Intern