Tidewater glacier retreat on Svalbard in the past, present and future

Abstract

Tidewater glaciers on Svalbard are sensitive indicators of climate change and play a crucial role for Arctic ecosystems. The widespread retreat of tidewater glaciers across Svalbard highlights the need to quantify retreat rates and project when these glaciers will become land-terminating. This study investigates tidewater glacier retreat during historical (1936–1990) and present (2012–2024) periods, examines spatial variability in retreat acceleration, and projects the timing of transition from tidewater to land-terminating glaciers under multiple retreat scenarios. Using glacier front positions derived from historical maps and recent satellite imagery, retreat rates for 209 tidewater glaciers were calculated. This was done by measuring distances from parallel retreat lines, besides the glacier’s centreline, to the intersection points with glacier front positions. Surge events were excluded to isolate climate-driven retreat. Later, parallel lines were intersected with two bedrock elevation models (Fürst et al., 2018; van Pelt & Frank, 2025). Present-day retreat rates were observed highest along the western coast of Spitsbergen − especially for larger glaciers within fjords, which are experiencing increased inflow of warm Atlantic water, highlighting the link between ocean temperature and frontal ablation. No glacier was found to have an advancing trend in any of the two periods. Statistical analysis revealed a significant increase (p = 8.00 × 10⁻²³) in mean retreat rates across all of Svalbard from 47 m yr⁻¹ historically to 111 m yr⁻¹ − more than twice the speed at present rates, with maximum rates rising during these periods from 251 to 613 m yr⁻¹. The acceleration factor varied spatially, with Nordaustlandet showing the highest factor (on average >6 times as high). The rest of Svalbard showed a strong increase in retreat as well, with 2.5 to 3 times higher rates today. Additionally, Monte Carlo simulations projected future glacier front positions under four retreat scenarios: historical, present, mean, and doubled present retreat rates. This indicated that tidewater glaciers on Spitsbergen are most vulnerable and will, despite considerable uncertainty, most probably become land-terminating within the next decades. Projections indicate that by 2050, approximately 56% of Svalbard’s tidewater glaciers will have become land-terminating, increasing to 75% by the end of this century. Climate change will further accelerate retreat, with applied double present-day retreat rate scenarios showing that these estimates decrease accordingly. The spatial variability underlines the influence of local bedrock topography on retreat patterns. While uncertainties remain due to surge exclusion and bedrock model variability, the results provide a baseline for forecasting tidewater glacier change on Svalbard and connections to other climate variables.

Popular Abstract

Tidewater glaciers, glaciers that end in the sea, are some of the clearest indicators of climate change in the Arctic. On Svalbard, a group of islands north of Norway, these glaciers are retreating rapidly. This affects ecosystems, ocean circulation, and the Arctic landscape.
This study investigates how 209 tidewater glaciers across Svalbard have changed over time, and how they are likely to change in the future. By comparing glacier front positions from historical maps and aerial photographs (1930s–1990) with recent satellite images (2012–2024), the speed at which glaciers are retreating was calculated. To focus on climate-driven changes, glacier surges, which are sudden and rapid advances of the glacier front, were excluded.
The results show that retreat has more than doubled in speed in recent decades: from an average of 47 meters per year historically to 111 meters per year today. Some glaciers, especially along the west coast of Spitsbergen, are retreating even faster. This could be due to warmer ocean water flowing into fjords. Glaciers also tended to retreat faster after surge events. No glacier showed an advancing trend in either time period.
To understand future changes, the study used retreat scenarios and two models of the land beneath the ice to estimate when glaciers will no longer reach the sea and become land-terminating. The projections suggest that by 2050, over half of Svalbard’s tidewater glaciers will have lost contact with the sea, rising to about 75 percent by the year 2100. If retreat rates continue to accelerate, as observed in the more recent time period, this transition could happen even sooner. The changes vary by region, northwestern Spitsbergen shows the fastest decline in number of tidewater glaciers, with most of them being smaller in size and volume. On the other hand, larger tidewater glaciers on Nordaustlandet remain in contact with the sea for over a hundred more years.
Although some uncertainty remains, especially about surge behaviour and the land beneath the ice, this study offers new insight into how quickly glaciers on Svalbard are responding to a warming climate.

• author: Luda, Ardis
• supervisor: Jack Kohler; Geir Moholdt; Martin Berggren
• organization: Dept of Physical Geography and Ecosystem Science
• course: NGEM01 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Earth and Environmental Sciences
• keywords: Geography, Physical Geography, Ecosystem Science, Tidewater glaciers, Svalbard, Glacier retreat, Glaciology, Bedrock topography, GIS, Python, Marine ecosystems, Climate change
• publication/series: Student thesis series INES
• report number: 720
• language: English
• additional info: Supervisors Jack Kohler and Geir Moholdt from the Norwegian Polar Institute, Tromsø, Norway.
• id: 9205516
• date added to LUP: 2025-06-25 09:15:20
• date last changed: 2025-06-27 16:03:53