SEA THE FUTURE

As a consequence of climate change, global warming is one of many stress factors affecting marine ecosystems. This literature-based overview therefore examines the temperature-related challenges facing kelp forests. Across species, a temperature-related decline in kelp is becoming apparent in various regions. This primarily affects equatorial border regions. As a result, shifts in distribution towards the poles can be observed. In addition, there are impacts on the ecosystem services provided by kelp. This means that ecological and economic functions are also under pressure. Models of species distribution and the following forecasts show that the impact and effects of ocean warming are likely to intensify in the future. However, regional data gaps make it difficult to interpret spatial and temporal trends. Appropriate monitoring can be valuable in this regard and contribute to the protection of kelp forests.

Since 1993, global mean sea level has risen by approximately 10.5 cm. The two pri- mary drivers are the thermal expansion of seawater as it absorbs excess atmospheric heat and the addition of water mass resulting from the melting glaciers and ice sheets. Coastal regions are therefore exposed to a high risk of flooding, which may lead to the permanent loss of valuable land and force millions of people to abandon their homes. To evaluate these risks at an early stage, various methods can be applied. In this study, a GIS-based risk assessment was conducted to model several scenarios of sea level rise. Jakarta, located on the northwest coast of the Indonesian island of Java, was selected as the case study area. Due to intensive groundwater extraction, the city is subsiding by up to 25 cm per year on average, which significantly amplifies its vulner- ability to rising sea levels. The GIS analysis revealed that in the +0.5 m scenario, ap- proximately x m2 of land would be permanently inundated. In the +1.0 m scenario, around x m2 would become unusable, and in the +1.5 m scenario, the affected area would increase to x m2. The results clearly show that flood protection measures are required even under a +0.5 m scenario. These measures may include raising coastal defenses or relocating vulnerable populations. Ultimately, the question arises as to whether long term reliance on protective infrastructure is feasible, or whether mitigation strategies aimed at limiting future sea level rise must be prioritized.

The coastal wetland ecosystems of mangrove forests provide valuable ecosystem services of climate change mitigation, biodiversity and coastal protection. The mangroves are affected by natural and anthropogenic drivers of ecological change. This literature review provides an overview of climate-change impacts on coastal mangrove habitats regarding their extent, ecological resilience and the atmospheric, hydrospheric and biogeophysical stressors acting upon them. We analysed the literature within WebOfScience for literature reviews and recent publications for a keyword-based systematic review. Mangrove forests appear to benefit from certain climate-change-related impacts including increasing air- and sea-surface temperatures and increased atmospheric CO₂ concentrations. However, their long-term development is strongly dependent on sediment availability, which is shaped not only by geomorphological conditions and human interventions but also by storm dynamics. Storm events can enhance sediment transport, yet extreme weather events such as cyclones exert detrimental effects on mangrove ecosystems. Altered precipitation regimes, drought, shifts in salinity, sea- level-rise-induced inundation and species invasions impose negative pressures on mangrove forests. This review highlights that local- and species-varying effects of sediment loads, available migration space, regionally sea-level-rise rates, changing tidal and hydrodynamic conditions significantly influence the capacity of mangrove ecosystems to adapt to climate change.