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The water balance of the Arctic tundra is shifting as permafrost stability, seasonality, and the ratio of precipitation to evaporation respond to amplified Arctic warming. While in some northern tundra locations there has been a notable increase in the number of water bodies, generally, the tundra landscape has experienced a decline in the number and area of lakes. We analyzed changes in small lake count (<10,000 m²), large lake count (>10,000 m²), and lake surface area across the periglacial tundra of western Greenland, using historical satellite and aerial imagery and weather data from the late 1960s to present. Overall, we found a decrease in lake count (21%) and surface area (2%) across our study region. Specifically, smaller ponds were particularly prone to change, with decreases of 28% in count and 15% in surface area. Shrinking lakes often became revegetated by both emergent aquatic and terrestrial vegetation, which captures potential successional trajectories following Arctic lake drying. Additionally, while annual precipitation may be increasing, it occurred primarily during the winter months in the form of snow, which may or may not contribute to the overall growing season water budget. Conversely, the peak growing season months of June, July, and August all have experienced significant increases in potential evaporation rates, thus likely creating a water deficit for much of the growing season. These results suggest that a large section of deglaciated Greenland appears likely to become drier in the summer months, which may result in widespread ecological consequences.

“Weather whiplash” is a colloquial phrase for describing an extreme event that includes shifts between two opposing weather conditions. Prior media coverage and research on these types of extremes have largely ignored winter weather events. However, rapid swings in winter weather can result in crossing from frozen to unfrozen conditions, or vice versa; thus, the potential impact of these types of events on coupled human and natural systems may be large. Given rapidly changing winter conditions in seasonally snow‐covered regions, there is a pressing need for a deeper understanding of such events and the extent of their impacts to minimize their risks. Here we introduce the concept of winter weather whiplash, defined as a class of extreme event in which a collision of unexpected conditions produces a forceful, rapid, back‐and‐forth change in winter weather that induces an outsized impact on coupled human and natural systems. Using a series of case studies, we demonstrate that the effects of winter weather whiplash events depend on the natural and human context in which they occur, and discuss how these events may result in the restructuring of social and ecological systems. We use the long‐term hydrometeorological record at the Hubbard Brook Experimental Forest in New Hampshire, USA to demonstrate quantitative methods for delineating winter weather whiplash events and their biophysical impacts. Ultimately, we argue that robust conceptual and quantitative frameworks for understanding winter weather whiplash events will contribute to the ways in which we mitigate and adapt to winter climate change in vulnerable regions.