Sea-ice indicators of polar bear habitat The Cryosphere DOI 10.5194/tc-10-2027-2016 14 September 2016 Polar bears, found in 19 distinct regions of the Arctic, depend on sea ice as a platform for hunting. Using satellite data of sea ice for the period 1979–2014, we found that the date of sea-ice retreat in spring is arriving weeks earlier, and the date of sea-ice advance in fall is arriving weeks later, in all 19 regions. We calculated several other measures of sea ice, which all show declines. These measures were designed to be useful for management agencies to assess polar bear habitat. Read more
Using present-day observations to detect when anthropogenic change forces surface ocean carbonate chemistry outside preindustrial bounds Biogeosciences DOI 10.5194/bg-13-5065-2016 13 September 2016 Ocean carbonate observations from surface buoys reveal that marine life is currently exposed to conditions outside preindustrial bounds at 12 study locations around the world. Seasonal conditions in the California Current Ecosystem and Gulf of Maine also exceed thresholds that may impact shellfish larvae. High-resolution observations place long-term change in the context of large natural variability: a necessary step to understand ocean acidification impacts under real-world conditions. Read more
Long-term visibility variation in Athens (1931–2013): a proxy for local and regional atmospheric aerosol loads Atmospheric Chemistry and Physics DOI 10.5194/acp-16-11219-2016 12 September 2016 Historical time series are unique sources of information for past climate and atmospheric composition change. The 82-year time series of visibility data collected at the National Observatory of Athens (NOA) was an excellent proxy for the long-term evolution of particulate pollution in the eastern Mediterranean, at times when direct aerosol measurements were missing. Evolution of particulate pollution of both local and regional origin is nicely reflected on visibility records of NOA. Read more
Interactions between climate change and human activities during the early to mid-Holocene in the eastern Mediterranean basins Climate of the Past DOI 10.5194/cp-12-1847-2016 12 September 2016 This paper focuses on early Holocene rapid climate changes in the Mediterranean zone, which are under-represented in continental archives, and on their impact on prehistoric societies from the eastern to central Mediterranean (central Anatolia, Cyprus, NE and NW Greece). Our study demonstrates the reality of hydrogeomorphological responses to early Holocene RCCs in valleys and alluvial fans and lake–marsh systems. We finally question their socio-economic and geographical adaptation capacities. Read more
Modified ion-Weibel instability as a possible source of wave activity at Comet 67P/Churyumov-Gerasimenko Annales Geophysicae DOI 10.5194/angeo-34-691-2016 31 August 2016 A new type of wave has been detected by the magnetometer of the Rosetta spacecraft close to comet P67/Churyumov-Gerasimenko. We provide the analytical model of this wave excitation from linear perturbation theory. A modified ion-Weibel instability is identified as source of this wave excited by a cometary current. The waves predominantly grow perpendicular to this current. A fan-like phase structure results from superposing the strongest growing waves in a cometary rest frame. Read more
New data on geology of the Southern Urals: a concise summary of research after the period of EUROPROBE activity Solid Earth DOI 10.5194/se-7-1269-2016 31 August 2016 The period between 1991 and 2005 was a time when many western geologists came to the Urals to get a closer look at this famous and extraordinarily rich region. The main reason was an openness policy of the USSR government, when foreigners were admitted to this area that was formerly almost closed. The co-operation of the western geologists with local specialists was very fruitful. The author aimed to describe the most interesting findings in Uralian geology after the learned guests left. Read more
Coherence among the Northern Hemisphere land, cryosphere, and ocean responses to natural variability and anthropogenic forcing during the satellite era Earth System Dynamics DOI 10.5194/esd-7-717-2016 30 August 2016 Using 3 decades of observational satellite and field data, we find that long-term changes in sea ice and sea level, plant phenology, and surface temperature are coherent with increases in atmospheric CO2 concentration and other global greenhouse gases. During the same period, natural causes of climate change should only have a net cooling long-term effect, suggesting the observed coherent pattern of changes across Earth’s biological and physical systems could only be due to human activities. Read more
Gravel threshold of motion: a state function of sediment transport disequilibrium? Earth Surface Dynamics DOI 10.5194/esurf-4-685-2016 29 August 2016 Accurately predicting gravel transport rates in mountain rivers is difficult because of feedbacks with channel morphology. River bed surfaces evolve during floods, influencing transport rates. I propose that the threshold of gravel motion is a state variable for channel reach evolution. I develop a new model to predict how transport thresholds evolve as a function of transport rate, and then use laboratory flume experiments to calibrate and validate the model. Read more
Why CO2 cools the middle atmosphere – a consolidating model perspective Earth System Dynamics DOI 10.5194/esd-7-697-2016 29 August 2016 Carbon dioxide, while warming the Earth’s surface, cools the atmosphere beyond about 15 km (the middle atmosphere). This cooling is considered a fingerprint of anthropogenic global warming, yet the physical reason behind it remains prone to misconceptions. Here we use a simple radiation model to illustrate the physical essence of stratospheric cooling, and a complex climate model to quantify how strongly different mechanisms contribute. Read more
A thermodynamic formulation of root water uptake Hydrology and Earth System Sciences DOI 10.5194/hess-20-3441-2016 29 August 2016 This theoretical paper describes the energy fluxes and dissipation along the flow paths involved in root water uptake, an approach that is rarely taken. We show that this provides useful additional insights for understanding the biotic and abiotic impediments to root water uptake. This approach shall be applied to explore efficient water uptake strategies and help locate the limiting processes in the complex soil–plant–atmosphere system. Read more
