Decadal Disruption of the QBO by Tropical Volcanic Supereruptions

The Los Chocoyos (14.6°N, 91.2°W) supereruption happened ∼75,000 years ago in Guatemala and was one of the largest eruptions of the past 100,000 years. It emitted enormous amounts of sulfur, chlorine, and bromine, with multi‐decadal consequences for the global climate and environment. Here, we simulate the impact of a Los Chocoyos‐like eruption on the quasi‐biennial oscillation (QBO), an oscillation of zonal winds in the tropical stratosphere, with a comprehensive aerosol chemistry Earth System Model. We find a ∼10‐year disruption of the QBO starting 4 months post eruption, with anomalous easterly winds lasting ∼5 years, followed by westerlies, before returning to QBO conditions with a slightly prolonged periodicity. Volcanic aerosol heating and ozone depletion cooling leads to the QBO disruption and anomalous wind regimes through radiative changes and wave‐mean flow interactions. Different model ensembles, volcanic forcing scenarios and results of a second model back up the robustness of our results

Mental health problems of children and adolescents at special schools for emotional and behavioral disorders

Bisher liegen für Deutschland kaum belastbare Daten zur Verbreitung psychischer Auffälligkeiten und zur Inanspruchnahme von Versorgungsleistungen von Schüler*innen an Förderschulen mit dem Förderschwerpunkt emotionale-soziale Entwicklung (FSP EsE) vor. Die vorliegende Studie geht daher der Fragestellung nach, wie häufig die unterschiedlichen Formen psychischer Auffälligkeiten an Förderschulen mit dem FSP EsE vorkommen und wie sich die Versorgungssituation betroffener Schüler*innen darstellt. Hierzu schätzten Lehrkräfte an sieben Förderschulen mit dem FSP EsE das Verhalten ihrer 6 – 18 Jahre alten Schüler*innen (N = 745) mit Hilfe des Fragebogens DISYPS-III (Döpfner & Görtz-Dorten, 2017) ein. 60,5% der Schüler*innen wurden als auffällig bzw. sehr auffällig im Bereich Aufmerksamkeitsdefizit-/ Hyperaktivitätsstörung (ADHS) beschrieben. Auffälligkeiten im Bereich oppositioneller Störungen (OPP) lagen aus Sicht der Lehrkräfte bei 42% aller Schüler*innen, im Bereich der Störung des Sozialverhaltens (SSV) bei 25,9%, der Angststörung bei 6,5% und der Depression bei 15,0% vor. Bei einem beträchtlichen Anteil der Schüler*innen wurden Auffälligkeiten in mehreren Bereichen gesehen, z. B. wiesen 47,1% derjenigen, die als auffällig im Bereich ADHS eingeschätzt wurden, auch Auffälligkeiten in Bezug auf OPP/ SSV auf. Bei 20,7% traten Symptome der SSV gemeinsam mit depressiven Problemen auf. Demgegenüber steht eine sehr viel geringere Anzahl an Schüler*innen, die außerschulische Unterstützungsleistungen wie Psychotherapie, Jugendhilfe etc. erhalten. (DIPF/Orig.)So far, there are no reliable data on the prevalence of mental health problems and the use of care services of students at special schools for emotional and behavioral disorders (EBD). Therefore, the current study investigates how often the different forms of mental disorders can be found at special schools for EBD and how the care situation of affected students can be described. As part of the PEARL research project, seven special schools for students with EBD (N = 745) were surveyed for mental health problems and the use of care services. Using the DISYPS-III questionnaire (Döpfner & Görtz-Dorten, 2017), teachers rated 60.5% of their 6 – 18 years old students to have severe problems in the area of ADHD. Symptoms of oppositional disorders (OPP) were present in 42% of all students, in the area of conduct disorder (CD) in 25.9%, anxiety disorder in 6.5%, and depression in 15.0%. A significant proportion of students were seen to have severe problems in multiple domains, e.g., 47.1% of those assessed as having symptoms of ADHD also had symptoms related to OPP/ SSV. In 20.7%, symptoms of SSV co-occurred with depressive problems. In contrast, there is a much smaller number of students who receive support services outside of school, such as psychotherapy, youth services, etc. (DIPF/Orig.

Interactive stratospheric aerosol models' response to different amounts and altitudes of SO2 injection during the 1991 Pinatubo eruption

A previous model intercomparison of the Tambora aerosol cloud has highlighted substantial differences among simulated volcanic aerosol properties in the pre-industrial stratosphere and has led to questions about the applicability of global aerosol models for large-magnitude explosive eruptions prior to the observational period. Here, we compare the evolution of the stratospheric aerosol cloud following the well-observed June 1991 Mt. Pinatubo eruption simulated with six interactive stratospheric aerosol microphysics models to a range of observational data sets. Our primary focus is on the uncertainties regarding initial SO2 emission following the Pinatubo eruption, as prescribed in the Historical Eruptions SO2 Emission Assessment experiments (HErSEA), in the framework of the Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP). Six global models with interactive aerosol microphysics took part in this study: ECHAM6-SALSA, EMAC, ECHAM5-HAM, SOCOL-AERv2, ULAQ-CCM, and UM-UKCA. Model simulations are performed by varying the SO2 injection amount (ranging between 5 and 10 Tg S) and the altitude of injection (between 18–25 km). The comparisons show that all models consistently demonstrate faster reduction from the peak in sulfate mass burden in the tropical stratosphere. Most models also show a stronger transport towards the extratropics in the Northern Hemisphere, at the expense of the observed tropical confinement, suggesting a much weaker subtropical barrier in all the models, which results in a shorter e-folding time compared to the observations. Furthermore, simulations in which more than 5 Tg S in the form of SO2 is injected show an initial overestimation of the sulfate burden in the tropics and, in some models, in the Northern Hemisphere and a large surface area density a few months after the eruption compared to the values measured in the tropics and the in situ measurements over Laramie. This draws attention to the importance of including processes such as the ash injection for the removal of the initial SO2 and aerosol lofting through local heating.</p

Aerosol size confines climate response to volcanic super-eruptions

Extremely large volcanic eruptions have been linked to global climate change, biotic turnover, and, for the Younger Toba Tuff (YTT) eruption 74,000 years ago, near-extinction of modern humans. One of the largest uncertainties of the climate effects involves evolution and growth of aerosol particles. A huge atmospheric concentration of sulfate causes higher collision rates, larger particle sizes, and rapid fall out, which in turn greatly affects radiative feedbacks. We address this key process by incorporating the effects of aerosol microphysical processes into an Earth System Model. The temperature response is shorter (9–10 years) and three times weaker (−3.5 K at maximum globally) than estimated before, although cooling could still have reached −12 K in some midlatitude continental regions after one year. The smaller response, plus its geographic patchiness, suggests that most biota may have escaped threshold extinction pressures from the eruption

Opinion: The scientific and community-building roles of the Geoengineering Model Intercomparison Project (GeoMIP) – past, present, and future

The Geoengineering Model Intercomparison Project (GeoMIP) is a coordinating framework, started in 2010, that includes a series of standardized climate model experiments aimed at understanding the physical processes and projected impacts of solar geoengineering. Numerous experiments have been conducted, and numerous more have been proposed as “test-bed” experiments, spanning a variety of geoengineering techniques aimed at modifying the planetary radiation budget: stratospheric aerosol injection, marine cloud brightening, surface albedo modification, cirrus cloud thinning, and sunshade mirrors. To date, more than 100 studies have been published that used results from GeoMIP simulations. Here we provide a critical assessment of GeoMIP and its experiments. We discuss its successes and missed opportunities, for instance in terms of which experiments elicited more interest from the scientific community and which did not, and the potential reasons why that happened. We also discuss the knowledge that GeoMIP has contributed to the field of geoengineering research and climate science as a whole: what have we learned in terms of intermodel differences, robustness of the projected outcomes for specific geoengineering methods, and future areas of model development that would be necessary in the future? We also offer multiple examples of cases where GeoMIP experiments were fundamental for international assessments of climate change. Finally, we provide a series of recommendations, regarding both future experiments and more general activities, with the goal of continuously deepening our understanding of the effects of potential geoengineering approaches and reducing uncertainties in climate outcomes, important for assessing wider impacts on societies and ecosystems. In doing so, we refine the purpose of GeoMIP and outline a series of criteria whereby GeoMIP can best serve its participants, stakeholders, and the broader science community

Analysis of the global atmospheric background sulfur budget in a multi-model framework

Sulfate aerosol in the stratosphere is an important climate driver, causing solar dimming in the years after major volcanic eruptions. Hence, a growing number of general circulation models are adapting interactive sulfur and aerosol schemes to improve the representation of relevant chemical processes and associated feedbacks. However, uncertainties of these schemes are not well constrained. Stratospheric sulfate is modulated by natural emissions of sulfur-containing species, including volcanic eruptive, and anthropogenic emissions. Model intercomparisons have examined the effects of volcanic eruptions, whereas the background conditions of the sulfur cycle have not been addressed in a global model intercomparison project. Assessing background conditions in global models allows us to identify model discrepancies as they are masked by large perturbations such as volcanic eruptions, yet may still matter in the aftermath of such a disturbance. Here, we analyze the atmospheric burden, seasonal cycle, and vertical and meridional distribution of the main sulfur species among nine global atmospheric aerosol models that are widely used in the stratospheric aerosol research community. We use observational and reanalysis data to evaluate model results. Overall, models agree that the three dominant sulfur species in terms of burdens (sulfate aerosol, OCS, and SO2) make up about 98 % of stratospheric sulfur and 95 % of tropospheric sulfur. However, models vary considerably in the partitioning between these species. Models agree that anthropogenic emission of SO2 strongly affects the sulfate aerosol burden in the Northern Hemispheric troposphere, while its importance is very uncertain in other regions. The total deposition of sulfur varies among models, deviating by a factor of two, but models agree that sulfate aerosol is the main form in which sulfur is deposited. Additionally, the partitioning between wet and dry deposition fluxes is highly model dependent. We investigate the areas of greatest variability in the sulfur species burdens and find that inter-model variability is low in the tropics and increases towards the poles. Seasonality in the southern hemisphere is depicted very similar among models. Differences are largest in the dynamically active northern hemispheric extratropical region, hence some of the differences could be attributed to the differences in the representation of the stratospheric circulation among underlying general circulation models. This study highlights that the differences in the atmospheric sulfur budget among the models arise from the representation of both chemical and dynamical processes, whose interplay complicates the bias attribution. Several problematic points identified for individual models are related to the specifics of the chemistry schemes, model resolution, and representation of cross-tropopause transport in the extratropics. Further model intercomparison research is needed focusing on the clarification of the reasons for biases, given also the importance of this topic for the stratospheric aerosol injection studies.</p

Eine künstliche stratosphärische Schwefelschicht: Der einfache Ausweg aus dem Klimaproblem?

An artificial stratospheric sulphur layer: The easy way out of the climate problem?: Sulfur, artificially introduced into the stratosphere (stratospheric aerosol intervention, SAI), forms small sulfur particles that scatters sunlight and thereby cools the Earth's surface. This chapter discusses the effects of SAI on climate and ozone, as well as the formation of the sulfur aerosols. Climate models simulate the consequences of SAI, with significant differences between models. This results in uncertainties in the climate impact, but also in the amounts of sulfur injection needed in the models to achieve a specific global temperature reduction