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Hypsometric amplification and routing moderation of Greenland ice sheet meltwater release

The Greenland ice sheet melts faster in a warmer climate. The ice sheet is flatter at high elevation, therefore atmospheric warming increases the melt area exponentially. For current climate conditions, we find that the ice sheet shape amplifies the total meltwater generation by roughly 60 %. Meltwater is not stored underneath the ice sheet, as previously found, but it does take multiple days for it to pass through the seasonally developing subglacial drainage channels, moderating discharge.

Debris-flow modeling at Meretschibach and Bondasca catchments, Switzerland: sensitivity testing of field-data-based entrainment model

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-17-801-2017
1 June 2017

This study describes a sensitivity analysis of the RAMMS debris-flow entrainment model, which is intended to help solve problems related to predicting the runout of debris flows. The results indicate that the entrainment model predicts plausible erosion volumes in comparison with field data. These eroded volumes are sensitive to the initial landslide volume, suggesting that this tool may be useful for both reconstruction of historical events and modeling of debris flow scenarios.

Non-linear effects of pore pressure increase on seismic event generation in a multi-degree-of-freedom rate-and-state model of tectonic fault sliding

The influence of fluid injection on tectonic fault sliding and generation of seismic events was studied in the paper by a multi-degree-of-freedom rate-and-state friction model with a two-parametric friction law. The considered system could exhibit different types of motion. The main seismic activity could appear directly after the start of fluid injection or in the post-injection phase (after some days or months). Such an influence of injection on seismicity is observed in the real cases.

The polar amplification asymmetry: role of Antarctic surface height

The Arctic has been warming much faster than the rest of the globe, including Antarctica. Here it was shown that one of the important mechanisms that sets Antarctica apart from the Arctic is heat transport from lower latitudes, and it was argued that a decrease in land height due to Antarctic melting would be favorable for increased atmospheric heat transport from midlatitudes. Other factors related to the larger Antarctic land height were also investigated.

Ozone and haze pollution weakens net primary productivity in China

While it is widely recognized that air pollutants adversely affect human health and climate change, their impacts on the regional carbon balance are less well understood. We apply an Earth system model to quantify the combined effects of ozone and aerosol particles on net primary production in China. Ozone vegetation damage dominates over the aerosol effects, leading to a substantial net suppression of land carbon uptake in the present and future worlds.

Process-level model evaluation: a snow and heat transfer metric

This work defines a metric for evaluation of a specific model snow process, namely, heat transfer through snow into soil. Heat transfer through snow regulates the difference in air temperature versus soil temperature. Accurate representation of the snow heat transfer process is critically important for accurate representation of the current and future state of permafrost. Utilizing this metric, we can clearly identify models that can and cannot reasonably represent snow heat transfer.

Divergence of seafloor elevation and sea level rise in coral reef ecosystems

We report regional-scale erosion of coral reef ecosystems in the Atlantic, Caribbean, and Pacific oceans determined by measuring changes in seafloor elevation. The magnitude of seafloor elevation loss has increased local sea level rise, causing water depths not predicted until near 2100, placing coastal communities at elevated and accelerating risk from hazards such as waves, storms, and tsunamis. Our results have broad implications for coastal resource and safety management.

Accounting for the climate–carbon feedback in emission metrics

Emission metrics such as GWP or GTP are used to put non-CO₂species on aCO₂-equivalentscale. In the fifth IPCC report the metrics are inconsistent, as the climate–carbon feedback is included only for CO₂but not for non-CO₂species. Here, we simulate a new impulse response function for the feedback, and we use it to correct the metrics. For instance, 1 g of CH₄is equivalent to 31 g of CO₂(instead of 28 g) following the corrected GWP100 metric. It is 34 g if other factors are also updated.

Constraining N2O emissions since 1940 using firn air isotope measurements in both hemispheres

Nitrous oxide is the third most important anthropogenic greenhouse gas with an increasing mole fraction. To understand its natural and anthropogenic sources we employ isotope measurements. Results show that while the N₂O mole fraction increases, its heavy isotope content decreases. The isotopic changes observed underline the dominance of agricultural emissions especially at the early part of the record, whereas in the later decades the contribution from other anthropogenic sources increases.

Characterization of the long-term radiosonde temperature biases in the upper troposphere and lower stratosphere using COSMIC and Metop-A/GRAS data from 2006 to 2014

Radiosonde observations (RAOBs) have provided the only long-term global in situ temperature measurements since 1958. In this study, we use Global Positioning System (GPS) radio occultation (RO) temperature data from 2006 to 2014 to characterize the inter-seasonal and interannual variability of temperature biases in the lower stratosphere. Results from this study also demonstrate the feasibility to use RO data to correct RAOB temperature biases for different sensor types.

COSMIC and Metop-A/GRAS data from 2006 to 2014">Read more

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