Chapter 4: Land and soils 

Karst landscapes occupy approximately 20% of terrestrial ice-free areas globally and are major geomorphological features in North America, Europe, the Middle East, Asia and Australia (Goldscheider et al. 2020).Land-use types of the global karst areas include forest (32%), bare area (28%), cropland (19%), grassland (11%), shrubland (7.2%), wetland (1.7%), ice and snow (1.2%) and urban (0.71%). The total area of global karst land-use change is 1.30 million km² (4.85% of global karst surface). Dominating land-use change trends are afforestation, urbanization and agricultural reclamation. The tropical climate has a higher intensity of land-use change in karst (Zhang et al. 2023).


Chapter 6: Freshwater

Karst aquifers are one of the main potable water sources worldwide (Stevanović 2019). About one quarter of the global population is completely or partially dependent on drinking water from karst aquifers. Both, the increase in temperature and a decrease of precipitation will affect the availability of karst water resources (Hartmann et al. 2014). 

It is often unrecognized in aquifers, where the groundwater is unseen until it emerges from wells and springs, and exacerbated by the perception of filtration through aquifers. While filtration occurs to some degree in porous media aquifers, it is effectively absent in karst aquifers and can result in deaths and serious illnesses (e.g. Worthington et al., 2002). Karst aquifers provide drinking water to nearly 700 million people (Stevanović, 2019, Goldscheider et al., 2020). Karst water resources are very sensitive to contamination and is likely to increase due to larger future industrial and agricultural productivity as a result of population growth (Hartmann et al. 2021). 

Additional losses in biodiversity occur from diminished water volumes in surface and aquifer flows (Bertoli 2022). Aquatic species are the first and primary species impacts, not just due to insufficient flows but concurrent changes in water temperature and chemistry, and less dilution of contaminants that enter the habitat. Spring-dependent species are especially vulnerable due to their adaptation to generally uniform habitat conditions, Loss of water also adversely impacts adjacent riparian species. US Fish and Wildlife Service (1996) describes such adverse impacts, including endangered species living inside karst aquifers that provide the source water for many spring-dependent aquatic ecosystems.

Karst groundwater-dependent ecosystems are important in terms of ecosystem services and biodiversity but increasingly under anthropogenic pressures and climate-change constraints. Most common threats are direct human disturbances (mass tourism, overfishing), water-quality deterioration and water shortage from aquifer overdraft. Although some sites are under protection, conservation measures are frequently insufficient (e.g. Siegel 2023).

Another worrying micropollutant are natural, regenerated and synthetic microfibres. Their potential faster degradation could release toxic compounds, and their characteristics could led to a long-term accumulation in groundwater and sediments (Balestra et al. 2024). 

Chapter 8: Interlinkages across environmental changes, scales and geographic regions and sub-regions  

Karst groundwater-dependent ecosystems in the Mediterranean region are important in terms of ecosystem services and biodiversity but increasingly under anthropogenic pressures and climate-change constraints. Most common threats are direct human disturbances (mass tourism, overfishing), water-quality deterioration and water shortage from aquifer overdraft. Although under protection, conservation measures are frequently insufficient (Xanke et al. 2024).