Prof. Debra Wunch has established a vibrant research effort at the University of Toronto where her leadership and scholarship have played a central role in enabling large space-based remote sensing efforts of greenhouse gases to flourish. Wunch is an extremely rigorous, agile, and effective scientist, thinker, and communicator, exactly the “right stuff” for the Ascent Award. She is an innovator who is making great strides to improve our understanding of greenhouse gases and the atmospheric and human processes that regulate their concentrations in the atmosphere. She works across a range of spatial scales. For methane, Wunch has developed an unusually comprehensive end-to-end approach, assembling an inventory with building-scale resolution, evaluating that inventory with ambient observations at high space and time resolution using mobile bicycle measurements, and evaluating the integrated emissions using remote sensing. Wunch is a pioneer of the Total Carbon Column Observing Network (TCCON). Her leadership in the early demonstrations, then as deputy chair representing the Americas beginning in 2016 and as chair of the entire network beginning in 2020, is a sign of the high esteem of her colleagues and a signal of the sort of leadership we expect of Ascent Award winners. Wunch extensively used measurements of vertical profiles over the TCCON sites to provide a traceable link between her absolute spectroscopic measurements and the primary gas standards from NOAA/World Meteorological Organization. She teased out critical systematic errors in this comparison, using her deep knowledge of spectroscopy, atmospheric structure, and the physics of the FTS spectrometers. She succeeded in demonstrating the absolute spectroscopy of CO₂ to better than 0.3 part per million (0.1%), a truly extraordinary achievement. In addition, she has distinguished herself with careful and insightful application of her measurements starting from her early paper on deriving CO₂ emissions from daily FTS data in Los Angeles (an instant classic) to her more recent work in understanding hemispheric exchanges of CO₂ and relating these to climatic variation. In that work she showed the evidence for a large temperature dependence of respiration in the boreal carbon cycle. This is a powerful statement about the future of the global carbon cycle in a warming world. Wunch’s work has shown the power of the total column, long time series measurements to challenge and falsify accepted wisdom and models. Please join us in honoring an exceptional scholar and colleague.

—Ronald C. Cohen, University of California, Berkeley