Estimates of future flood risk rely on projections from climate models. The relatively few climate models used to analyze future flood risk cannot easily quantify of their associated uncertainties. In this study, we demonstrated that the projected fluvial flood changes estimated by a new generation of climate models, the collectively known as Coupled Model Intercomparison Project Phase 6 (CMIP6), are similar to those estimated by CMIP5. The spatial patterns of the multi-model median signs of change (+ or −) were also very consistent, implying greater confidence in the projections. The model spread changed little over the course of model development, suggesting irreducibility of the model spread due to internal climate variability, and the consistent projections of models from the same institute suggest the potential to reduce uncertainties caused by model differences. Potential global exposure to flooding is projected to be proportional to the degree of warming, and a greater threat is anticipated as populations increase, demonstrating the need for immediate decisions.

Abstract. Supraglacial debris affects the response of glaciers to climate change by altering the reflectivity of solar radiation and conductive heat flux. To accurately assess the contribution of glacier melts to sea level rise, water resources and natural 10 hazards, it is important to account for the effects of debris. However, due to the practical difficulties of global-scale field measurements, information regarding the spatial distribution of the thickness and thermal properties of debris on glaciers is limited; hence, the effects of debris on glacier melting are not explicitly taken into account in current global glacier models. In this study, we developed a dataset of the thermal resistance of debris on glaciers at 90-m resolution derived from multi-temporal satellite images and satellite-derived radiation data at the global scale, excluding Greenland, Antarctica, and some of the Arctic. 15We found that supraglacial debris covered 16.8% of the entire analyzed glacial area. The highest debris cover percentage occurred in New Zealand, and the lowest was in Iceland. The area of thick debris (which suppresses glacier melting) was about two times that of thin debris (which accelerates glacier melting), indicating that the insulation effect of debris to inhibit glacier melting may dominate at the global scale. The distribution of debris was also related to the slope aspect of glaciers. Despite the limitations of this study, the resulting global distribution of the thermal resistance of debris can be incorporated into global 20 glacier models, and hence it provides a solid basis for evaluating the effects of debris on glacial melting.

No abstract

No abstract

No abstract

No abstract

The disappearing of glaciers in Himalaya alpine region, in where hundreds of millions of people rely on melting glaciers for water, has been reported by recent studies. However, the estimation of change in glacier mass still has a significant challenge because of a limited observational methodology to understand hydrological processes in Himalaya region. In this study, we estimate the ice loss rate for the Himalaya alpine region for the period January 2003 through December 2008, mainly using terrestrial water storage (TWS) variations observed by the Gravity Recovery and Climate Experiment (GRACE). To separate the effect of the other TWS components, simulated soil moisture, snow mass and river storage are calculated by using the Minimal Advanced Treatment of Surface Interaction and Runoff (MATSIRO) land surface model (LMS).The methodology using GRACE data and LMS result is similar to one of previous studies. In addition, we also use groundwater withdrawal data, and our estimated glacier mass change is compares with glacier model (HYOGA) results. Finally, it is estimated that the melting rate of the glacier mass over target region is approximately 4.7 Gt/year. Although we believe that our methodology is the newest comparing previous one, our estimated value is much underestimated than HYOGA results. Our methodological experience and information will be helpful to better understand glacier mass change.