Long-term deposition and condensation ice-nucleatingparticle measurements from four stations across the globe Atmospheric Chemistry and Physics DOI 10.5194/acp-20-15983-2020 20 January 2021 Long-term ice-nucleating particle (INP) data are presented from four semi-pristine sites located in the Amazon, the Caribbean, Germany and the Arctic. Average INP concentrations did not differ by orders of magnitude between the sites. For all sites short-term variability dominated the time series, which lacked clear trends and seasonalities. Common drivers to explain the INP levels and their variations could not be identified, illustrating the complex nature of heterogeneous ice nucleation. Read more
Emergent constraints on equilibrium climate sensitivity in CMIP5: do they hold for CMIP6? Earth System Dynamics DOI 10.5194/esd-11-1233-2020 19 January 2021 As an important measure of climate change, the Equilibrium Climate Sensitivity (ECS) describes the change in surface temperature after a doubling of the atmospheric CO 2 concentration. Climate models from the Coupled Model Intercomparison Project (CMIP) show a wide range in ECS. Emergent constraints are a technique to reduce uncertainties in ECS with observational data. Emergent constraints developed with data from CMIP phase 5 show reduced skill and higher ECS ranges when applied to CMIP6 data. Read more
Brief communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica The Cryosphere DOI 10.5194/tc-14-4603-2020 18 January 2021 The West Antarctic Ice Sheet has long been considered geometrically prone to collapse, and Thwaites Glacier, the largest glacier in the Amundsen Sea, is likely in the early stages of disintegration. Using observations of Thwaites Glacier velocity and elevation change, we show that the transport of ~2 km 3 of water beneath Thwaites Glacier has only a small and transient effect on glacier speed relative to ongoing thinning driven by ocean melt. Read more
Downsizing parameter ensembles for simulations of rare floods Natural Hazards and Earth System Sciences DOI 10.5194/nhess-20-3521-2020 15 January 2021 This work proposes methods for reducing the computational requirements of hydrological simulations for the estimation of very rare floods that occur on average less than once in 1000 years. These methods enable the analysis of long streamflow time series (here for example 10 000 years) at low computational costs and with modelling uncertainty. They are to be used within continuous simulation frameworks with long input time series and are readily transferable to similar simulation tasks. Read more
Biases in the albedo sensitivity to deforestation in CMIP5 models and their impacts on the associated historical radiative forcing Earth System Dynamics DOI 10.5194/esd-11-1209-2020 14 January 2021 Trees are darker than crops or grasses; hence, they absorb more solar radiation. Therefore, land cover changes modify the fraction of solar radiation reflected by the land surface (its albedo), with consequences for the climate. We apply a new statistical method to simulations conducted with 15 recent climate models and find that albedo variations due to land cover changes since 1860 have led to a decrease in the net amount of energy entering the atmosphere by −0.09 W m 2 on average. Read more
Quantifying CO2 emissions of a city with the Copernicus Anthropogenic CO2 Monitoring satellite mission Atmospheric Measurement Techniques DOI 10.5194/amt-13-6733-2020 13 January 2021 The European CO2M mission is a proposed constellation of CO 2 imaging satellites expected to monitor CO 2 emissions of large cities. Using synthetic observations, we show that a constellation of two or more satellites should be able to quantify Berlin’s annual emissions with 10–20 % accuracy, even when considering atmospheric transport model errors. We therefore expect that CO2M will make an important contribution to the monitoring and verification of CO 2 emissions from cities worldwide. Read more
New global characterisation of landslide exposure Natural Hazards and Earth System Sciences DOI 10.5194/nhess-20-3413-2020 12 January 2021 Landslides cause thousands of fatalities and cost billions of dollars of damage worldwide every year, but different inventories of landslide events can have widely diverging completeness. This can lead to spatial biases in our understanding of the impacts. Here we use a globally homogeneous model of landslide hazard and exposure to provide consistent estimates of where landslides are most likely to cause damage to people, roads and other critical infrastructure at 1 km resolution. Read more
Tropical Pacific climate variability under solar geoengineering: impacts onENSO extremes Atmospheric Chemistry and Physics DOI 10.5194/acp-20-15461-2020 11 January 2021 Solar geoengineering has been introduced to mitigate human-caused global warming by reflecting sunlight back into space. This research investigates the impact of solar geoengineering on the tropical Pacific climate. We find that solar geoengineering can compensate some of the greenhouse-induced changes in the tropical Pacific but not all. In particular, solar geoengineering will result in significant changes in rainfall, sea surface temperatures, and increased frequency of extreme ENSO events. Read more
Sea ice dynamics in the Bransfield Strait, Antarctic Peninsula, during the past 240 years: a multi-proxy intercomparison study Climate of the Past DOI 10.5194/cp-16-2459-2020 8 January 2021 We tested the applicability of the organic biomarker IPSO 25 for sea ice reconstructions in the industrial era at the western Antarctic Peninsula. We successfully evaluated our data with satellite sea ice observations. The comparison with marine and ice core records revealed that sea ice interpretations must consider climatic and sea ice dynamics. Sea ice biomarker production is mainly influenced by the Southern Annular Mode, while the El Niño–Southern Oscillation seems to have a minor impact. Read more
Optical characterization of pure pollen types using a multi-wavelength Raman polarization lidar Atmospheric Chemistry and Physics DOI 10.5194/acp-20-15323-2020 7 January 2021 Measurements of the multi-wavelength Raman polarization lidar Polly XT have been combined with measurements of pollen type and concentration using a traditional pollen sampler at a rural forest site in Kuopio, Finland. The depolarization ratio was enhanced when there were pollen grains in the atmosphere, illustrating the potential of lidar to track pollen grains in the atmosphere. The depolarization ratio of pure pollen particles was assessed for birch and pine pollen using a novel algorithm. Read more
