Ongoing Research Projects

My work generally follows several directions, which can be disparate at times but are all aimed at a single goal:
Understanding how climate variability affects the risks associated with extreme weather events around the world.
You can find more details on all of my current research projects in the pages below; see also my Publications page.

 
 
Satellite sea surface temperature (SST) from December 2015. Photo credit: NOAA

Satellite sea surface temperature (SST) from December 2015. Photo credit: NOAA

El Nino/Southern Oscillation Dynamics

The El Nino/Southern Oscillation, or ENSO, is the dominant driver of year-to-year climate variability around the world. Although the basic mechanisms (quasi-periodic changes to the tropical Pacific trade winds) are becoming better understood, it is still not clear exactly how external (natural and anthropogenic) influences affect the properties of El Nino and La Nina events. I use coupled climate model simulations to study the mechanisms for these responses.

 
Data from the US Drought Monitor as of February 7, 2016. Red colors indicate more extreme drought.

Data from the US Drought Monitor as of February 7, 2016. Red colors indicate more extreme drought.

Multidecadal Megadroughts

Drought conditions in arid regions like the southwestern US can be extreme at times. But although 20th and 21st century droughts have had severe impacts on water resources, our best estimates from paleoclimate data indicate that past droughts have been even more severe and prolonged. I work with both paleoclimate reconstructions and climate models to understand the causes and risks associated with these "megadroughts".

 
Fossil coral sample on Christmas Island (Kiribati) being processed for transport back to the lab.

Fossil coral sample on Christmas Island (Kiribati) being processed for transport back to the lab.

Improving Coral Paleoclimate Reconstructions

In order to understand how tropical Pacific variability may respond to climate change, we need to build up good statistics of how it has varied in the past. But the El Nino/Southern Oscillation changes over long timescales, meaning that our observational records are far too short. Coral reconstructions are the best source of information on past ENSO variability, but our ability to use them quantitatively is limited by our lack of detailed physical understanding of how El Nino and La Nina events lead to changes in temperature and seawater isotopic composition in reef environments. I use field observations, regional ocean models, and large-scale observational products to find ways to improve reconstruction accuracy from coral records.

 
Kilauea caldera, Hawaii, August 2012.

Kilauea caldera, Hawaii, August 2012.

 


Volcanic Influences on Climate

Volcanoes have had major impacts on climate and weather over the past few decades: for example, the eruption of Mt. Pinatubo in 1991, among others. But looking back farther in time, there have been eruptions which were MUCH stronger than anything we've seen in the 20th century. The eruption of Mt. Tambora in 1815, for instance, affected weather around the world and is even thought to have inspired Mary Shelley to write 'Frankenstein'. I combine data from paleoclimate reconstructions (corals as well as tree rings) with output from climate models to better understand the physics of how different types of volcanic eruptions affect climate - and what that might mean for eruptions in the future.