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Stratospheric ozone changes under solar geoengineering: implications for UV exposure and air quality

Various forms of solar radiation management (SRM) have been proposed to counteract man-made climate change. However, all these countermeasures could have unintended side-effects. We add a novel perspective to this discussion by showing how atmospheric ozone changes under solar geoengineering could affect UV exposure and air pollution. This would have implications for human health and ecology. Atmospheric composition changes are therefore important to consider in the evaluation of any SRM scheme.

Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 ∘C global warming could be dangerous

We use climate simulations, paleoclimate data and modern observations to infer that continued high fossil fuel emissions will yield cooling of Southern Ocean and North Atlantic surfaces, slowdown and shutdown of SMOC & AMOC, increasingly powerful storms and nonlinear sea level rise reaching several meters in 50-150 years, effects missed in IPCC reports because of omission of ice sheet melt and an insensitivity of most climate models, likely due to excessive ocean mixing.

Phase, composition, and growth mechanism for secondary organic aerosol from the ozonolysis of α-cedrene

A significant fraction of airborne particles, which have significant impacts on human health, visibility, and climate, are formed from the oxidation of gaseous precursors to generate low-volatility products. We show here that a sesquiterpene, α-cedrene, efficiently forms high-viscosity semisolid particles with complex composition via mechanisms that involve the highly reactive Criegee intermediate and that high molecular weight products play an important role in new particle formation.

Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

The aim of this article is to present an experimental campaign over the Mediterranean focused on aerosol-radiation measurements and modeling. Results indicate an important atmospheric loading associated with a moderate absorbing ability of mineral dust. Observations suggest a complex vertical structure and size distributions characterized by large aerosols within dust plumes. The radiative effect is highly variable, with negative forcing over the Mediterranean and positive over northern Africa.

Updated ozone absorption cross section will reduce air quality compliance

As an air pollutant, O3 is monitored photometrically to assess compliance with air quality legislation. A recent study found a 1.8% reduction in its absorption cross section, which would lead to an equivalent increase in observed O3 concentrations. We estimate this would increase the number of sites out of compliance with air quality regulations in the EU and US by 20%. We draw attention to how small changes in gas metrology impacts attainment and compliance with legal air quality standards.

Observations of the spectral dependence of linear particle depolarization ratio of aerosols using NASA Langley airborne High Spectral Resolution Lidar

The manuscript describes measurements of particle depolarization ratio from the NASA airborne HSRL-2 at three wavelengths, for two dust cases and a smoke case. Differences in the spectral dependence of particle depolarization ratio are due to the sizes of the non-spherical particles, large for dust and small for smoke. The large depolarization at 355nm for smoke has not been previously reported and may impact aerosol typing when only a single wavelength is available.

NASA Langley airborne High Spectral Resolution Lidar">Read more

Laboratory evidence of organic peroxide and peroxyhemiacetal formation in the aqueous phase and implications for aqueous OH

This paper demonstrates organic peroxide and peroxyhemiacetal formation during aqueous photooxidation of methylglyoxal using ultra-high-resolution Fourier transform ion cyclotron resonance electrospray ionization mass spectrometry (FTICR-MS). Then, we provide simulation results of organic peroxide/peroxyhemiacetal formation in clouds and wet aerosols and discuss organic peroxides as a source of condensed-phase OH radicals and as a contributor to aqueous secondary organic aerosol (SOA).

Ice water content vertical profiles of high-level clouds: classification and impact on radiative fluxes

We discuss the shape of ice water content (IWC) vertical profiles in high ice clouds and its effect on radiative properties of these clouds, both in short- and in long-wave bands (SW and LW). We suggest a set of primitive shapes (rectangular, isosceles trapezoid, lower and upper triangle) and propose a statistical parameterization using ice water path (IWP) as a single parameter. We estimate and explain simulated differences in LW/SW atmospheric radiances for suggested IWC shapes.

The importance of Asia as a source of black carbon to the European Arctic during springtime 2013

We show that during the springtime of 2013, the anthropogenic pollution particularly from sources in Asia, contributed significantly to black carbon across the European Arctic free troposphere. In contrast to previous studies, the contribution from open wildfires was minimal. Given that Asian pollution is likely to continue to rise over the coming years, it is likely that the radiative forcing in the Arctic will also continue to increase.

Evaluating the climate and air quality impacts of short-lived pollutants

This paper presents a summary of the findings of the ECLIPSE EU project. The project has investigated the climate and air quality impacts of short-lived climate pollutants (especially methane, ozone, aerosols) and has designed a global mitigation strategy that maximizes co-benefits between air quality and climate policy. Transient climate model simulations allowed quantifying the impacts on temperature (e.g., reduction in global warming by 0.22K for the decade 2041-2050) and precipitation.

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