‘Life is very short and what we have to do must be done in the now.’

-Audre Lorde


Katie Brennan

PhD candidate (she/her)

University of Washington


My name is Katie Brennan and I’m a graduate student in the department of Atmospheric Sciences at the University of Washington. My research interests include Arctic sea ice, climate of the past, climate variablilty and data assimilation. I am advised by Professor Greg Hakim and also work closely with Professor Cecilia Bitz and Professor Ed Blanchard-Wrigglesworth. I am currently a National Science Foundation Graduate Research Fellow.

Some big picture research questions I keep coming back to include:

  • How unprecendented are the current changes to Arctic sea ice?
  • How will/did the global climate system respond to large changes in Arctic sea ice conditions?

I am passionate about equity in STEM and community outreach and enjoy pushing our community to do more and do better. I’m a 3rd generation Washingtonian, currently living and working on the traditional unceded lands of the Duwamish People. In my free time I enjoy backcountry skiing, climbing, running, biking, hiking, sewing, crafting and playing my ukulele.


  • Arctic sea ice
  • Climate variaiblity
  • Data assimilation
  • Climate of the past


  • PhD in Atmospheric Sciences, expected 2022

    University of Washington

  • MS in Atmospheric Sciences, 2019

    University of Washington

  • BA in Mathematics and Physics, 2013

    Lewis and Clark College

Tools I like to use:


Open source languages for life.


Data assimilation is one of my favorite statistical tools that allows you to optimally combine models and observations. But I also rely on many others to analyze my reconstructions and other data.

Climate models

Mostly I analyze and use output from global climate model simulations to acquire likely climate states and understand the relationship between climate variables.


Direct observations are great when you have them! When available I like to use satellite and other types of direct observations.

Proxy data

Proxy data (ice cores, tree rings, corals, sediment cores, etc.) can provide useful information when direct observations of climate varaibles are not available, particularly when looking at time periods before 1850.

Publications: submitted or in prep

Quickly discover relevant content by filtering publications.
(2020). Do multimodel ensembles deliver a superior posterior in paleoclimate data assimilation?.

(2020). Reconstructed Arctic Sea-Ice Conditions in the Common Era.


Quickly discover relevant content by filtering publications.
(2020). Magnitudes and spatial patterns of interdecadal temperature variability in CMIP6. Geophysical Research Letters.

Code DOI

(2020). Arctic Sea-Ice Variability During the Instrumental Era. Geophysical Research Letters.


(2014). Measuring Lipid Membrane Viscosity Using Rotational and Translational Probe Diffusion. Physical Review Letters.


Recent & Upcoming Talks

Arctic sea ice response to early 20th century warming

Arctic sea ice response to early 20th century warming

Poster: Reconstructing Arctic sea ice over the past two millennia with the Last Millennium Reanalysis framework