Exploring the hidden geotechnical and contaminated land consequences of climate change in Sweden
Sweden presents a fascinating paradox. As a global leader in climate mitigation with one of the lowest greenhouse gas emission intensities in the European Union 6 , the Nordic nation is simultaneously confronting a hidden crisis brewing beneath its surface. While Sweden successfully decoupled economic growth from major environmental pressures and aims for net-zero emissions by 2045, its very foundation is becoming increasingly unstable 6 .
The country is warming at nearly twice the global average, with temperatures rising by approximately 2°C since the late 19th century 5 .
Over 82% of Swedes live in coastal regions, far exceeding the EU average of 42% 5 .
This rapid warming triggers more frequent extreme weather events—from devastating Hurricane Gudrun in 2005 to unprecedented droughts and wildfires in 2018—that are fundamentally altering the relationship between Sweden's soil and its structures 5 .
To understand how climate change affects Sweden's ground stability, we must first explore a specialized field of engineering: unsaturated soil mechanics. Most traditional geotechnical engineering assumes soils are either completely dry or fully saturated with water. In reality, the vast majority of soils supporting our infrastructure exist in an intermediate state—partially saturated—in what's known as the vadose zone 1 .
In unsaturated soils, water is held between soil particles through surface tension, creating a negative pore water pressure scientifically known as matric suction 1 . This suction acts like a hidden glue, binding soil particles together and significantly enhancing soil strength.
| Soil Water Constant | Engineering Significance | Climate Impact |
|---|---|---|
| Saturation | Water movement dominated by gravity | Increased landslide risk during extreme rainfall |
| Field Capacity | Optimal for plant growth | Drought alters balance, affecting slope-stabilizing vegetation |
| Permanent Wilting Point | Plants cannot extract water | Increased drought frequency causes desiccation cracks |
The theoretical framework of unsaturated soil mechanics translates into tangible consequences across Sweden. The Swedish Geotechnical Institute has identified numerous areas at risk of landslides, mudslides, and erosion, particularly concerning given Sweden's high population density in coastal and river areas 5 . A total of 131 of Sweden's 290 municipalities are located in these vulnerable zones, where shifting soil conditions pose direct threats to communities and infrastructure 5 .
Beneath Sweden's modern cities and picturesque landscapes lies a hidden legacy of industrial and agricultural activities. Historical operations—from mining in Bergslagen to industrial activities in Stockholm, Gothenburg, and Malmö—have left a complex pattern of contamination in soils and groundwater 4 .
Among the most concerning contaminants are per- and polyfluoroalkyl substances (PFAS), often called "forever chemicals" due to their extreme persistence in the environment . These synthetic chemicals, used since the 1950s in various industrial and consumer applications, pose unique challenges:
| Contaminant | Primary Sources | Health Concerns |
|---|---|---|
| PFAS | Firefighting foam, industrial applications | Liver damage, immune system effects |
| Petroleum Hydrocarbons | Storage leaks, transportation spills | Carcinogenic, nervous system effects |
| Heavy Metals | Historical mining, industry | Neurological damage, organ failure |
| Nitrates | Agricultural fertilizers | "Blue baby" syndrome, cancer risks |
Climate change acts as a multiplier to Sweden's contaminated land challenges through several mechanisms:
Concentrates pollutants in remaining water bodies
Sweden faces a daunting challenge with potentially thousands of PFAS-contaminated sites, and few cost-effective remediation techniques currently exist . The Swedish Environmental Protection Agency is working with other agencies through a 2022-2027 government assignment to identify and manage these sites, but the scope is enormous .
In the heart of Sweden's capital, the Stockholm Royal Seaport redevelopment project represents one of Europe's most ambitious approaches to addressing contaminated land in an era of climate change 9 . The site's industrial history—particularly gas production—left behind significant contamination including tar, benzene, and heavy metals across different soil layers 9 .
The most groundbreaking approach deployed at the Kolkajen phase of the project is called ISS-ISCO (In Situ Stabilisation and Solidification – In Situ Chemical Oxidation). This method addresses two challenges simultaneously: soil contamination and structural instability 9 .
This project represents Europe's largest application of this treatment method, providing valuable insights for similar challenges throughout Sweden and beyond 9 .
Using a specialized machine weighing over 100 tonnes, with a mixing tool diameter of two meters
Stabilizes clay soils and prevents future settlement damage
Breaks down organic contaminants into carbon dioxide and water 9
The Stockholm Royal Seaport project employs a diverse toolkit of remediation strategies, selected based on contamination profile, depth, and future land use:
Used for shallower contaminants above groundwater level
Leveraging microorganisms to break down contaminants naturally
This comprehensive approach has enabled reuse of 1,330,000 tons of rock and excavation materials, significantly reducing transportation needs for disposal 9 .
Despite these innovations, Sweden faces significant challenges in scaling climate adaptation efforts. According to OECD assessments, public funding for climate change adaptation has been insufficient and inconsistent 5 .
The primary funding source—the Civil Contingencies Agency's 2:2 fund for natural disaster prevention—disbursed around SEK 500 million (0.01% of GDP) in 2023, dramatically short of estimated needs 5 .
There are also concerning disparities in adaptive capacity. A survey found that 60% of large cities had dedicated adaptation budgets, compared to only 30% of smaller municipalities 5 . This capacity gap is particularly problematic given that smaller municipalities often host extensive infrastructure and contaminated sites requiring sophisticated management.
Source: OECD assessments 5
Sweden's research landscape is actively responding to these dual challenges of geotechnical instability and contaminant mobilization. Formas, the Swedish research council for environment, agricultural sciences, and spatial planning, funds innovative projects through calls like "Explore," which supports research on environment, agricultural sciences, and spatial planning with an overarching perspective on sustainable development 7 .
The ground beneath Sweden is undergoing a silent transformation. As climate change accelerates, the interplay between shifting soil mechanics and mobilized contamination creates complex challenges that demand integrated solutions. The paradigms of the past—which often treated geotechnical engineering and environmental remediation as separate domains—are no longer adequate.
Sweden's path forward requires embracing the complexity of coupled thermo-hydro-mechanical processes in soils while acknowledging the persistent nature of legacy contamination. Success will depend on:
As Sweden continues its leadership in climate mitigation, building similar expertise and commitment in climate adaptation—particularly addressing the hidden challenges beneath our feet—will determine the resilience of communities for generations to come. The lessons learned from Sweden's experience offer valuable insights for nations worldwide confronting similar challenges at the intersection of climate change, geotechnical engineering, and environmental protection.