Application of copper(II)-based chemicals induces CH3Br and CH3Cl emissions from soil and seawater

Methyl bromide (CH3Br) and methyl chloride (CH3Cl) are major carriers of atmospheric bromine and chlorine, respectively, which can catalyze stratospheric ozone depletion. However, in our current understanding, there are missing sources associated with these two species. Here we investigate the effect of copper(II) on CH3Br and CH3Cl production from soil, seawater and model organic compounds: catechol (benzene-1,2-diol) and guaiacol (2-methoxyphenol). We show that copper sulfate (CuSO4) enhances CH3Br and CH3Cl production from soil and seawater, and it may be further amplified in conjunction with hydrogen peroxide (H2O2) or solar radiation. This represents an abiotic production pathway of CH3Br and CH3Cl perturbed by anthropogenic application of copper(II)-based chemicals. Hence, we suggest that the widespread application of copper(II) pesticides in agriculture and the discharge of anthropogenic copper(II) to the oceans may account for part of the missing sources of CH3Br and CH3Cl, and thereby contribute to stratospheric halogen load.

Assessing the consequences of including aerosol absorption in potential Stratospheric Aerosol Injection Climate Intervention Strategies

Theoretical Stratospheric Aerosol Intervention (SAI) strategies model the deliberate injection of aerosols or their precursors into the stratosphere thereby reflecting incident sunlight back to space and counterbalancing a fraction of the warming due to increased concentrations of greenhouse gases. This cooling mechanism is known to be relatively robust through analogues from explosive volcanic eruptions which have been documented to cool the climate of the Earth. However, a practical difficulty of SAI strategies is how to deliver the injection high enough to ensure dispersal of the aerosol within the stratosphere on a global scale. Recently, it has been suggested that including a small amount of absorbing material in a dedicated 10-day intensive deployment might enable aerosols or precursor gases to be injected at significantly lower, more technologically-feasible altitudes. The material then absorbs sunlight causing a localised heating and ‘lofting’ of the particles, enabling them to penetrate into the stratosphere. Such self-lofting has recently been observed following the intensive wildfires in 2019–2020 in south east Australia, where the resulting absorbing aerosol penetrated into the stratosphere and was monitored by satellite instrumentation for many months subsequent to emission. This study uses the fully coupled UKESM1 climate model simulations performed for the Geoengineering Model Intercomparison Project (GeoMIP) and new simulations where the aerosol optical properties have been adjusted to include a moderate degree of absorption. The results indicate that partially absorbing aerosols i) reduce the cooling efficiency per unit mass of aerosol injected, ii) increase deficits in global precipitation iii) delay the recovery of the stratospheric ozone hole, iv) disrupt the Quasi Biennial Oscillation when global mean temperatures are reduced by as little as 0.1 K, v) enhance the positive phase of the wintertime North Atlantic Oscillation which is associated with floods in Northern Europe and droughts in Southern Europe. While these results are dependent upon the exact details of the injection strategies and our simulations use ten times the ratio of black carbon to sulfate that is considered in the recent intensive deployment studies, they demonstrate some of the potential pitfalls of injecting an absorbing aerosol into the stratosphere to combat the global warming problem.

Unusual high total ozone over New Delhi on 25 March 1990- A case study

An unusual high total ozone value of 373 Dobson unit was observed over New Delhi on 25 March 1990. It is attributed to the leakage of stratospheric ozone into troposphere through tropopause break in association with a trough in mid-tropospheric westerlies with its axis lying along 82° E longitude north of 20° N, at 300 hPa level.

A Putatively New Family of Alphaproteobacterial Chloromethane Degraders from a Deciduous Forest Soil Revealed by Stable Isotope Probing and Metagenomics

Background: Chloromethane (CH3 Cl) is the most abundant halogenated organic compound in the atmosphere and substantially responsible for the destruction of the stratospheric ozone layer. Since anthropogenic CH 3 Cl sources have become negligible with the application of the Montreal Protocol (1987), natural sources, such as vegetation and soils, have increased proportionally in the global budget. CH3 Cl-degrading methylotrophs occurring in soils might be an important and overlooked sink.Results & Conclusions: The objective of our study was to link the biotic CH3 Cl sink with the identity of active microorganisms and their biochemical pathways for CH3 Cl degradation in a deciduous forest soil. When tested in laboratory microcosms, biological CH3 Cl consumption occurred in leaf litter, senescent leaves, and organic and mineral soil horizons. Highest consumption rates, around 2 mmol CH3 Cl g -1 dry weight h -1 , were measured in organic soil and senescent leaves, suggesting that top soil layers are active (micro-)biological CH 3 Cl degradation compartments of forest ecosystems. The DNA of these [13C]-CH3 Cl-degrading microbial communities was labelled using stable isotope probing (SIP), and the corresponding taxa and their metabolic pathways studied using high-throughput metagenomics sequencing analysis. [ 13C]-labelled Metagenome-Assembled Genome closely related to the family Beijerinckiaceae may represent a new methylotroph family of Alphaproteobacteria, which is found in metagenome databases of forest soils samples worldwide. Gene markers of the only known pathway for aerobic CH3 Cl degradation, via the methyltransferase system encoded by the CH3 Cl utilisation genes (cmu), were undetected in the DNA-SIP metagenome data, suggesting that biological CH3 Cl sink in this deciduous forest soil operates by a cmu-independent metabolism.

Sustainable Development: Asia-Pacific Perspectives

The Asia-Pacific region has been experiencing rapid development in the past 30 years, and issues relating to sustainable development will become increasingly important in the coming decades. This comprehensive overview presents sustainable development from the perspectives of Asia and the Pacific, with contributions from more than 70 leading international experts. The first part focuses on the theories and practices of sustainable development, including national and regional perspectives, as well as international policies and law concerning climate change. The second part highlights the challenges and opportunities of sustainable development and poverty reduction amid the changing ecological, social, cultural, economic, and political environment in this region. These include issues such as the importance of science for sustainable development and related areas, including sustainable energy, stratospheric ozone depletion, climate change, land-use change, biodiversity, and disaster risk reduction. The volume is an invaluable reference for all researchers and policy makers with an interest in sustainable development.

Variability and trends in surface solar spectral ultraviolet irradiance in Italy: on the influence of geopotential height and lower-stratospheric ozone

The short- and long-term variability of the surface spectral solar ultraviolet (UV) irradiance is investigated across Italy using high-quality ground-based measurements from three locations: Aosta (45.7∘ N, 7.4∘ E, 570 m a.s.l.), Rome (41.9∘ N, 12.5∘ E, 15 75 m a.s.l.), and Lampedusa (35.5∘ N, 12.6∘ E, 50 m a.s.l.). The three sites are characterized by different environmental conditions and represent almost the full latitudinal extent of the Italian territory. Data of two periods were analysed: 2006–2020 (all sites) and 1996–2020 (Rome only). The main objective of this study is to quantify the effect of the geopotential height (GPH) at 250 hPa on total ozone, and spectral irradiance at 307.5 and 324 nm. We first show that monthly anomalies in GPH, total ozone, and spectral irradiances are correlated amongst the three sites, suggesting that Italy is often affected by the same synoptical weather systems. We further find statistically significant anticorrelations between GPH and monthly anomalies in total ozone for all stations and months. Conversely, we identify positive correlations between GPH and monthly anomalies in spectral irradiance at 307.5 nm for most months. The influence of GPH on short-term variability also hold for long-term trends. For example, long-term changes in total ozone over the period 2006–2020 were associated with changes in GPH for all stations. This suggests that observed negative trends in total ozone were mainly driven by changes in lower-stratospheric ozone as upper-stratospheric ozone was increasing over this period. For several months of the year, positive trends in UV irradiance were observed, and we found that these trends were predominantly caused by changes in clouds and/or aerosols instead of total ozone. For the longer period of 1996–2020, a statistically significant annualized decrease in total ozone of ∼ 0.1 % per year was identified for Rome and could subsequently be attributed to decreasing lower-stratospheric ozone. While positive trends in spectral irradiance at 307.5 nm were observed for several months of this extended period, the negative trend in total ozone did not lead to a positive trend in the spectral irradiance at 307.5 nm in the deseasonalized data. Our study provides evidence that dynamical processes taking place in the troposphere lead to significant variability in total ozone and surface solar UV irradiance.

Impact of Using a New High-Resolution Solar Reference Spectrum on OMI Ozone Profile Retrievals

We evaluated a new high-resolution solar reference spectrum for characterizing space-borne Ozone Monitoring Instrument (OMI) measurements as well as for retrieving ozone profile retrievals over the ultraviolet (UV) wavelength range from 270 to 330 nm. The SAO2010 solar reference has been a standard for use in atmospheric trace gas retrievals, which is a composite of ground-based and balloon-based solar measurements from the Kitt Peak National Observatory (KPNO) and Air Force Geophysics Laboratory (AFGL), respectively. The new reference spectrum, called the TSIS-1 Hybrid Solar Reference Spectrum (HSRS), spans 202–2730 nm at a 0.01 to ~0.001 nm spectral resolution. The TSIS-1 HSRS in the UV region of interest in this study is a composite of AFGL and ground-based solar measurements from the Quality Assurance of Spectral Ultraviolet Measurements In Europe (QASUME) campaign, with a radiometric calibration that used the lower resolution Spectral Irradiance Monitor (SIM) instrument on the space-based Total and Spectral Solar Irradiance Sensor-1 (TSIS-1) mission. The TSIS-1 HSRS radiometric uncertainties were below 1% whereas those of SAO2010 ranged from 5% in the longer UV part to 15% in the shorter UV part. In deriving slit functions and wavelength shifts from OMI solar irradiances, the resulting fitting residuals showed significant improvements of 0.5–0.7% (relatively, 20–50%) due to switching from the SAO2010 to the TSIS-1 HSRS. Correspondingly, in performing ozone profile retrievals from OMI radiances, the fitting residuals showed relative improvements of up to ~5% in 312–330 nm with relative differences of 5–7% in the tropospheric layer column ozone; the impact on stratospheric ozone retrievals was negligible.

Ozonsimulationen mit ICON für die Verbesserung von UV-Vorhersagen

<p class="Default">Ozon (O<sub>3</sub>) in der Stratosphäre absorbiert die biologisch schädliche ultraviolette Strahlung der Sonne (den größten Teil der UV-B-Strahlung) und verhindert, dass sie die Erdoberfläche erreicht. Die energiereiche UV-Strahlung kann das genetische Material in den Zellen von Pflanzen und Tieren, sowie von Menschen zerstören. Ohne die stratosphärische Ozonschicht wäre das Leben auf der Erde, wie wir es kennen, nicht möglich.</p> <p class="Default">Der Deutsche Wetterdienst (DWD) stellt UV-Indexkarten zur Verfügung, um die Bevölkerung bezgl. hoher UV-Belastungen zu informieren und zu warnen [1]. Dazu werden Daten aus dem golobalen Vorhersagemodell ICON (ICOsahedral Non-hydrostatic model) [2], externe Ozondaten und ein eigenes UV-Modell verwendet, um eine Vorhersage des UV-Index zu erstellen, der z.B. auf der DWD-Webseite als Vorhersage visualisiert wird.</p> <p class="Default">In diesem Projekt wird in Zusammenarbeit mit dem DWD ein selbstkonsistentes System entwickelt, um UV-Indexkarten vollständig mittels ICON zu generieren. Zu diesem Zweck wird ein linearisiertes Ozonschema (LINOZ) [3] für tägliche Ozonvorhersagen optimiert. Dies geschieht als Erweiterung der ICON-ART Struktur [4] [5] (ART: Aerosols and Reactive Trace gases). Für die Berechnung von UV-Strahlungsflüssen und -indizes wurde ein Strahlungstransportmodell für Sonnenstrahlung (Cloud-J) [6] implementiert und angepasst. Da das gesamte System als effiziente Lösung für UV-Indexvorhersagen dem DWD zur Verfügung gestellt werden soll, wird besonders Wert auf eine umfassende Funktionalität bei sehr geringem Rechenaufwand gelegt. Ein wichtiger Teil der Arbeit ist daher auch die Validierung und Optimierung der Verfahren und Abläufe, um zuverlässige und qualitativ hochwertige Vorhersagen zu erstellen.</p> <p class="Default">Wir präsentieren erste Ergebnisse des von ICON-ART modellierten UV-Strahlungsflusses durch die Atmosphäre auf globaler Skala und über ausgewählten Gebieten, dessen tageszeitliche Variation, sowie den Einfluss von Wolken auf die UV-Intensität.</p> <p><strong>Anmerkung:</strong></p> <p>Dieses Projekt wird durch den Deutschen Wetterdienst im Rahmen der Extramuralen Forschung mit folgender Nummer gefördert: 4819EMF03.</p> <p><strong>Referenzen:</strong></p> <p>[1]  https://kunden.dwd.de/uvi/index.jsp</p> <p>[2]   Zängl, G., et al., The ICON (ICOsahedral Non-hydrostatic) modelling framework of DWD MPI-M: Description of the non-hydrostatic dynamical core. Q.J.R. Meteorol. Soc., 141(687), 563-579 (2014)</p> <p>[3]   McLinden, C. A., et al., Stratospheric ozone in 3-D models: A simple chemistry and the cross-tropopause flux, Journal of Geophysical Research: Atmospheres, 105(D11), 14653-14665 (2000)</p> <p>[4]  Rieger, D., et al., ICON-ART - A new online-coupled model system from the global to regional scale, Geosci. Model Dev., 8(6), 1659-1676 (2015)</p> <p>[5]  Schröter, et al., ICON-ART 2.1: a flexible tracer framework and its application for composition studies in numerical weather forecasting and climate simulations. Geosci. Model Dev., 11(10), 4043-4068 (2018)</p> <p>[6]  Prather, M.J., Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c. Geosci. Model Dev., 8(8), 2587-2595 (2015)</p>