The effects of adaptation and mitigation on coastal flood impacts during the 21st century. An application of the DIVA and IMAGE models

This paper studies the effects of mitigation and adaptation on coastal flood impacts. We focus on a scenario that stabilizes concentrations at 450 ppm-CO₂-eq leading to 42 cm of global mean sea-level rise in 1995–2100 (GMSLR) and an unmitigated one leading to 63 cm of GMSLR. We also consider sensitivity scenarios reflecting increased tropical cyclone activity and a GMSLR of 126 cm. The only adaptation considered is upgrading and maintaining dikes. Under the unmitigated scenario and without adaptation, the number of people flooded reaches 168 million per year in 2100. Mitigation reduces this number by factor 1.4, adaptation by factor 461 and both options together by factor 540. The global annual flood cost (including dike upgrade cost, maintenance cost and residual damage cost) reaches US$ 210 billion per year in 2100 under the unmitigated scenario without adaptation. Mitigation reduces this number by factor 1.3, adaptation by factor 5.2 and both options together by factor 7.8. When assuming adaptation, the global annual flood cost relative to GDP falls throughout the century from about 0.06 % to 0.01–0.03 % under all scenarios including the sensitivity ones. From this perspective, adaptation to coastal flood impacts is meaningful to be widely applied irrespective of the level of mitigation. From the perspective of a some less-wealthy and small island countries, however, annual flood cost can amount to several percent of national GDP and mitigation can lower these costs significantly. We conclude that adaptation and mitigation are complimentary policies in coastal areas.     

The effectiveness of climate clubs under Donald Trump

On 1 June 2017, President Trump announced that the US intends to leave the Paris Agreement if no alternative terms acceptable to his administration can be agreed upon. In this article, an agent-based model of bottom-up climate mitigation clubs is used to derive the impact that lack of US participation may have on the membership of such clubs and their emissions coverage. We systematically analyse the prospects for climate mitigation clubs, depending on which of three conceivable roles the US takes on: as a leader (for benchmarking), as a follower (i.e. willing to join climate mitigation clubs initiated by others if this is in its best interest) or as an outsider (i.e. staying outside of any climate mitigation club no matter what). We investigate these prospects for three types of incentives for becoming a member: club goods, conditional commitments and side-payments. Our results show that lack of US leadership significantly constrains climate clubs’ potential. Lack of US willingness to follow others’ lead is an additional, but smaller constraint. Only in a few cases will US withdrawal entail widespread departures by other countries. We conclude that climate mitigation clubs can function without the participation of an important GHG emitter, given that other major emitters show leadership, although these clubs will rarely cover more than 50% of global emissions.

Key policy insights

• The US switching from being a leader to being a follower substantially reduces the emissions coverage of climate mitigation clubs.

• The US switching from being a follower to being an outsider sometimes reduces coverage further, but has a smaller impact than the switch from leader to follower.

• The switch from follower to outsider only occasionally results in widespread departures by other countries; in a few instances it even entices others to join.

• Climate mitigation clubs can function even without the participation of the US, provided that other major emitters show leadership; however, such clubs will typically be unable to cover more than 50% of global emissions.

• Climate mitigation clubs may complement the Paris Agreement and can also serve as an alternative in case Paris fails.

     

Surface analysis of stratospheric dust particles

Abstract— A controversially discussed and yet central question in interplanetary dust particle (IDP) research is the degree of alteration of these particles during their residence in the stratosphere. Especially, the typical enrichment of Br in chondritic IDPs (on the average ～21 × CI) has been inferred to be a result of contamination processes, probably invoking aerosol droplets. With time-of-flight secondary ion mass spectrometry (TOF-SIMS), we examined the surfaces of 13 stratospheric particles from the dust collector U2071. Six particles had severe, surface-bound, silicone oil residues preventing a proper analysis of their surfaces. Six other particles—-according to our scanning electron microscopy, energy dispersive x-ray spectrometer (SEM-EDS) studies preclassified as one (Fe,Ni)S-rich IDP, one Ca-rich particle, and four aluminum-oxide spheres—-carry the halogens F, Cl, and Br on the surface. At least for the aluminum-oxide spheres, we provide unequivocal evidence for a surface correlation of halogens. This evidence, taken together with that from previous studies, proves a general stratospheric contamination process which has to be considered in IDP research.     

A combined ToF‐SIMS and EMP/SEM study of a three‐phase symplectite in the Los Angeles basaltic shergottite

Abstract— A rare three‐phase symplectite consisting of Ca‐rich pyroxene, Fe‐rich olivine, and a silica phase is frequently found rimming pyroxene in the Martian meteorite Los Angeles. This assemblage is usually interpreted as the breakdown product of metastable pyroxferroite, a very rare pyroxenoid mineral itself. However, its origin is not entirely understood, mainly because the extremely small average size of the constituent phases represents a challenge for precise high‐resolution analysis. In addition to electron microbeam methods, the present study uses time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) to overcome the limits of spatial resolution and to comprehensively study this mineral assemblage. The prevailing breakdown hypothesis is supported by the following results: (1) The three symplectite phases are very homogenous in composition from 100 μm down to the micrometer scale. (2) The silica phase could be shown to be almost pure SiO². (3) The symplectite bulk composition is consistent with pyroxferroite. Sub‐micrometer sized Ti‐oxide grains are found within the symplectite (but not within the Ca‐rich pyroxene) and probably represent a minor breakdown phase in addition to the three main phases.     

The Venus ground-based image Active Archive: A database of amateur observations of Venus in ultraviolet and infrared light

The Venus ground-based image Active Archive is an online database designed to collect ground-based images of Venus in such a way that they are optimally useful for science. The Archive was built to support ESA's Venus Amateur Observing Project, which utilizes the capabilities of advanced amateur astronomers to collect filtered images of Venus in ultraviolet, visible and near-infrared light. These images complement the observations of the Venus Express spacecraft, which cannot continuously monitor the northern hemisphere of the planet due to its elliptical orbit with apocenter above the south pole. We present the first set of observations available in the Archive and assess the useability of the data set for scientific purposes.     

Using Fuzzy Logic for the Analysis of Sea-level Indicators with Respect to Glacial-isostatic Adjustment: An Application to the Richmond-Gulf Region,Hudson Bay

An important constraint for the inference of mantle viscosity is the variation of the Holocene relative sea-level (RSL) height (with respect to today) following the last deglaciation. As a measure of this variation, sea-level indicators (SLIs) related to the RSL heights at specific past time epochs are used. For the inversion of the RSL-height change in terms of mantle viscosity, neighbouring SLIs may be grouped into an RSL diagram taken as representative for the region considered. Usually, the nominal height and age of a particular SLI are the only characteristics considered when determining the former RSL height. However, only SLIs based on isolation basins yield a narrow range for this height, whereas SLIs based on fossil samples provide a lower bound (shells), an upper bound (driftwood) or a finite interval (basal peat) for it. To also use fossil samples objectively, we develop a classification scheme of the depositional conditions based on fuzzy logic. After the definition of appropriate membership functions, this method leads to a systematic interpretation of the large number of SLIs available. We apply this method to SLIs from the Richmond-Gulf region, southeastern Hudson Bay, near the former glaciation center of Canada and derive a decay time of 5 ka for the exponential function best fitting the RSL diagram for this region.