I am currently an Earth Institute Postdoctoral Research Scientist at Columbia University. Housed at The Center for International Earth Science Information Network (CIESIN), my primary research examines how climate change is affecting urban population exposure to extreme heat. Additionally, in collaboration with the Popgrid Data Collaborative, I am leading a project that explores how gridded population data can be used to track the United Nations Sustainable Development Goals. I also continue to work on urban food security/systems research in sub-Saharan Africa.
I received my PhD in Geography from the University of California, Santa Barbara, where I worked with the WAVES Lab, directed by Professor Kelly Caylor, UCSB's Earth Research Institute, Climate Hazards Center, and the National Center for Ecological Analysis and Synthesis (NCEAS). My disseration focused on the converging challenges of climate change, urbanization, and food security in Africa. As a scientist, I not only have an obligation to communicate the complexity of these problems, but to also maintain objectivity in light of the often divergent public, political, and scientific discourse. To this end, I am keen to leverage cutting-edge data science methods to engender evidenced-based policy and private sector solutions that reduce risk to climate change among the most vulnerable populations worldwide.
I employ a combination of remote-sensed imagery and GIS analysis, machine learning applications, household survey design and implementation, and statistical modeling to accomplish my research objectives. Much of my research relies on developing geospatial code in Python, though I am literate in R and desktop applications such as ENVI, QGIS and ArcGIS Pro. Funded as a U.S. Borlaug Fellow in Global Food Security, I have conducted household surveys in Accra, Ghana, and Lusaka, Zambia, to examine the environmental, socioeconomic, and spatial determinants of household food security within large African cities.
Prior to graduate school, my path weaved from studying International Affairs at The George Washington University, to hunting guinea worm in Northern Ghana, to working on Capitol Hill, and to teaching English in Sliven, Bulgaria, under a Fulbright Scholarship. This global tableau of experience cultivated my understanding of the complex and sometimes conflicting relationship between transformative science, idealistic public policy, and the practical political and local limitations of employing scientific research to enact positive change. By investigating climate change, urbanization, and food security, I seek to advance applied Earth systems science to address pressing global human-environmental challenges.
El Salvador © 2016 Cascade Tuholske
Research: Identifying Urban Population Pressures Across Africa
Africa is projected to add 1,000,000,000 new urban residents by 2050. Yet developing sustainable solutions to tackle the host of challenges posed by rapid urban population growth is stymied by a lack municipality-level population data across the continent. We simply do not know how many people live in most African towns and cities. To fill this gap, I built a geo-spatial algorithm that couples crowd-sourced GIS data and large-scale population raster datasets to measure the population of over 4,500 urban settlements.
My results (published in Environmental Research Letters) reveal that 77% to 85% of urban settlements in Africa have fewer than 100,000 people and that at least 50% of Africa's urban population live in urban settlements with fewer than 1 million residents. Across almost all African countries, the urban population distribution shifted towards larger cities between 2000 and 2015. However, in arid regions, my results indicate that small- and medium-sized urban settlements are absorbing a greater share of urban population growth compared to large urban settlements.
I am now integrating these results with economic and climatological datasets to understand how Africa's smaller urban settlements interact with broader environmental and economic challenges. I am keen to develop solutions to ensure that Africa's growing urban populations can contend with the challenges posed by climate change.
Choma District, Zambia © 2017 Cascade Tuholske
Chamonix, France © 2016 Cascade Tuholske
I am always looking for collaborations, suggestions, and general banter. Please feel free to email me at cascade (at) ciesin.columbia.edu or check me out on social media.