Overview
Dr. Jonathan “Johnny” Ryan is a glaciologist who is interested in ice sheet surface processes. His research has investigated several key components that influence the accumulation and ablation of ice sheets, including snowfall, clouds, melt-albedo feedbacks, and supraglacial hydrology. To conduct this research, Johnny primarily relies on satellite remote sensing. This expertise has earned him selection onto NASA’s ICESat-2 and Terra/Aqua/Suomi Science Teams. Johnny also conducts field research and has spent many summers surveying ice sheets and glaciers with uncrewed aerial systems (UAS) or drones. His primary research site is the Greenland Ice Sheet, where he has worked out of Kangerlussuaq and Uummannaq. He has also conducted research on the Northern Patagonia Icefield and the Oregon Cascades. By combining fieldwork with new satellite remote sensing technology, Johnny’s research bridges spatial and temporal scales to generate new insights into ice sheet surface processes. The significance of his research is reflected by recent first- and second-author publications in journals such as Nature, Environmental Research Letters, Science Advances, Nature Communications, and Geophysical Research Letters.
Current Appointments & Affiliations
Recent Publications
Greenland ice sheet runoff reduced by meltwater refreezing in bare ice.
Journal Article Nature communications · September 2025 The contribution of Greenland Ice Sheet meltwater runoff to global sea-level rise is accelerating due to increased melting of its bare-ice ablation zone. There is growing evidence, however, that climate models overestimate runoff from this critical area of ... Full text CiteMeltwater ponding has an underestimated radiative effect on the surface of the Greenland Ice Sheet.
Journal Article Nature communications · September 2025 Ponding of meltwater on the surface of the Greenland Ice Sheet has the potential to reduce ice sheet albedo and amplify mass loss. However, this process remains poorly constrained and is absent from models that project ice sheet mass balance. Here we demon ... Full text CiteContribution of surface and cloud radiative feedbacks to Greenland Ice Sheet meltwater production during 2002–2023
Journal Article Communications Earth and Environment · December 1, 2024 Greenland Ice Sheet meltwater runoff projections are essential for accurate forecasts of global sea-level rise. However, melt depends on complex interactions between climate warming, surface albedo, and clouds, which are challenging to simulate in models. ... Full text CiteRecent Grants
Constraining surface water radiative feedbacks on the Greenland Ice Sheet using very high resolution imagery
ResearchCo Investigator · Awarded by National Aeronautics and Space Administration · 2026 - 2027Retrieval of glacier ice and snow properties over the Greenland Ice Sheet from ICESat-2
ResearchPrincipal Investigator · Awarded by National Aeronautics and Space Administration · 2025 - 2027Role of clouds on Greenland Ice Sheet surface melt
ResearchPrincipal Investigator · Awarded by National Aeronautics and Space Administration · 2024 - 2026View All Grants