Wie wirkt der Klimawandel auf das Leben im Meer?

Laut jüngstem Sachstandsbericht des Weltklimarats sind viele aktuelle Veränderungen auf den Kontinenten und in den Weltmeeren auf den Klimawandel zurückzuführen. Die menschengemachten CO2-Emissionen sind Haupttreiber des globalen Temperaturanstiegs; CO2 wird aber auch in Meerwasser gelöst und verursacht dadurch eine Versauerung der Ozeane. Gleichzeitig führen die zunehmende Erwärmung, Schichtung und Eutrophierung der Meere regional unterschiedlich zu verstärktem Verlust von Sauerstoff. Wirken Erwärmung, Versauerung und Sauerstoffarmut zusammen, reagieren Meeresbewohner besonders empfindlich auf den Klimawandel

Changing Salinity Gradients in the Baltic Sea As a Consequence of Altered Freshwater Budgets

Climate change is expected to enhance the hydrological cycle in northern latitudes reducing the salinity in the Baltic Sea, a land-locked marginal sea with a large catchment area located in northern Europe. With the help of ocean simulations forced by historical atmospheric and hydrological reconstructions and local observations, we analyzed long-term changes in the sea surface salinity of the Baltic Sea as well as its latitudinal gradient. The variability of both is dominated by multidecadal oscillations with a period of about 30 years, while both atmospheric variables, wind and river runoff, contribute to this variability. Centennial changes show a statistically significant positive trend in the North-South gradient of sea surface salinity for 1900–2008. This change is mainly attributed to increased river runoff from the northernmost catchment indicating a footprint of the anthropogenic impact on salinity with consequences for the marine ecosystem and species distributions

The devastating Zhouqu storm-triggered debris flow of August 2010: Likely causes and possible trends in a future warming climate

On 8 August 2010 in the northwestern Chinese province of Gansu, a rainstorm-triggered debris flow devastated the small county of Zhouqu. A modeling study, using a new multiple-phase scalable and extensible geofluid model, suggests that the cause is an intersection of several events. These were a heavy rainstorm, not necessarily the result of global warming, which triggered the landslide and followed a drought that created surface cracks and crevasses; the geology of the region, notably the loess covering heavily weathered surface rock; and the bedrock damage, that deepened the surface crevasses inflicted by the 7.9 magnitude Wenchuan earthquake of 12 May 2008. Deforestation and topsoil erosion were critical contributors to the massive size of the debris flow. The modeling results underscore the urgency for a high-priority program of revegetation of Zhouqu County, without which the region will remain exposed to future disastrous, “progressive bulking” type landslides. Debris flows are more predictable types of landslides; consequently, a series of “pseudo climate change” model experiments of future extreme precipitation events are carried out using the Weather Research and Forecasting model, forced by temperature perturbations from an ensemble of climate models. In a possibly future warmer climate, extreme precipitation events are anticipated to be more severe, and this study has identified an atmospheric blocking pattern that might produce future extreme precipitation events in the peri-Tibetan Plateau (TP) area (located to the northeast of the TP). Importantly, observations from gravity field measuring satellites indicate that the larger geological environment of this region also is becoming increasingly unstable