Stopping the flood: could we use targeted geoengineering to mitigate sea level rise? The Cryosphere DOI 10.5194/tc-12-2955-2018 20 September 2018 In this paper, we explore the possibility of using locally targeted geoengineering to slow the rate of an ice sheet collapse. We find that an intervention as big as existing large civil engineering projects could have a 30 % probability of stopping an ice sheet collapse, while larger interventions have better odds of success. With more research to improve upon the simple designs we considered, it may be possible to perfect a design that was both achievable and had good odds of success. Read more
Tracing water masses with 129I and 236U in the subpolar North Atlantic along the GEOTRACES GA01 section Biogeosciences DOI 10.5194/bg-15-5545-2018 18 September 2018 The investigation of water mass transport pathways and timescales is important to understand the global ocean circulation. Following earlier studies, we use artificial radionuclides introduced to the oceans in the 1950s to investigate the water transport in the subpolar North Atlantic (SPNA). For the first time, we combine measurements of the long-lived iodine-129 and uranium-236 to confirm earlier findings/hypotheses and to better understand shallow and deep ventilation processes in the SPNA. GEOTRACES GA01 section">Read more
sympl (v. 0.4.0) and climt (v. 0.15.3) – towards a flexible framework for building model hierarchies in Python Geoscientific Model Development DOI 10.5194/gmd-11-3781-2018 18 September 2018 In the same way that the fruit fly or the yeast cell serve as model systems in biology, climate scientists use a range of computer models to gain a fundamental understanding of our climate system. These models range from extremely simple models that can run on your phone to those that require supercomputers. Sympl and climt are packages that make it easy for climate scientists to build a hierarchy of such models using Python, which facilitates easy to read and self-documenting models. Read more
Speculations on the application of foliar 13C discrimination to reveal groundwater dependency of vegetation and provide estimates of root depth and rates of groundwater use Hydrology and Earth System Sciences DOI 10.5194/hess-22-4875-2018 18 September 2018 Groundwater is a significant water resource for humans and for groundwater-dependent vegetation. Several challenges to managing both groundwater resources and dependent vegetation include defining the location of dependent vegetation, the rate of groundwater use, and the depth of roots accessing groundwater. In this study we demonstrate a novel application of measurements of stable isotopes of carbon that can be used to identify the location, the rooting depth, and the rate of groundwater use. Read more
Inverse modelling of CF4 and NF3 emissions in East Asia Atmospheric Chemistry and Physics DOI 10.5194/acp-18-13305-2018 17 September 2018 Emissions of carbon tetrafluoride CF4, NF3 and CHF3 in east Asia have been calculated using atmospheric measurements and an atmospheric transport model. We calculate emissions of CF4 to be quite constant between the years 2008 and 2015 for both China and South Korea, with 2015 emissions calculated at 4.33 ± 2.65 Gg yr-1 and 0.36 ± 0.11 Gg yr-1, respectively. Emission estimates of NF3 from South Korea could be made with relatively small uncertainty at 0.6 ± 0.07 Gg yr-1 in 2015. Read more
The climate effects of increasing ocean albedo: an idealized representation of solar geoengineering Atmospheric Chemistry and Physics DOI 10.5194/acp-18-13097-2018 12 September 2018 Marine cloud brightening has been proposed as a means of geoengineering/climate intervention, or deliberately altering the climate system to offset anthropogenic climate change. In idealized simulations that highlight contrasts between land and ocean, we find that the globe warms, including the ocean due to transport of heat from land. This study reinforces that no net energy input into the Earth system does not mean that temperature will necessarily remain unchanged. Read more
Wet avalanches: long-term evolution in the Western Alps under climate and human forcing Climate of the Past DOI 10.5194/cp-14-1299-2018 11 September 2018 In the context of a warming climate, mountain environments are especially vulnerable to a change in the risk pattern. Our study focuses on the past evolution of wet avalanches, likely triggered by warmer temperatures destabilizing the snow cover. In the last 3300 years we observed an increase of wet avalanche occurrence related to human activities, intensifying pressure on forest cover, as well as favorable climate conditions such as warmer temperatures coinciding with retreating glacier phases. Read more
Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet The Cryosphere DOI 10.5194/tc-12-2883-2018 7 September 2018 In Tibet, two glaciers suddenly collapsed in summer 2016 and produced two gigantic ice avalanches, killing nine people. This kind of phenomenon is extremely rare. By combining a detailed modelling study and high-resolution satellite observations, we show that the event was triggered by an increasing meltwater supply in the fine-grained material underneath the two glaciers. Contrary to what is often thought, this event is not linked to a change in the thermal condition at the glacier base. Read more
Integrated management of a Swiss cropland is not sufficient to preserve its soil carbon pool in the long term Biogeosciences DOI 10.5194/bg-15-5377-2018 6 September 2018 It is of great interest to know whether croplands act as a net source or sink of atmospheric CO2and if soil carbon © stocks are preserved over long timescales due to the role of C in soil fertility. For a cropland in Switzerland it was found that managing the field under the Swiss framework of the Proof of Ecological Performance (PEP) resulted in soil C losses of 18.0 %. Additional efforts are needed to bring Swiss management practices closer to the goal of preserving soil C in the long term. Read more
Technical note: Two types of absolute dynamic ocean topography Ocean Science DOI 10.5194/os-14-947-2018 4 September 2018 Two types of marine geoid exist with the first type being the average level of sea surface height if the water is at rest (classical definition), and the second type being satellite-determined with the condition that the water is usually not at rest. The associated absolute dynamic ocean topography (DOT) also has two types. Horizontal gradients of the two DOTs are different with the 1st (2nd) type representing the absolute (relative) surface geostrophic currents. Read more
