Anja Schmidt

University of Cambridge | Cam

Several biotic crises during the past 300 million years have been linked to episodes of continental flood basalt volcanism, and in particular to the release of massive quantities of magmatic sulphur gas species. Flood basalt provinces were typically formed by numerous individual eruptions, each lasting years to decades. However, the environmental i...

The 2014–2015 Bárðarbunga-Veiðivötn fissure eruption at Holuhraun produced about 1.5 km3 of lava, making it the largest eruption in Iceland in more than 200 years. Over the course of the eruption, daily volcanic sulfur dioxide (SO2) emissions exceeded daily SO2 emissions from all anthropogenic sources in Europe in 2010 by at least a factor of 3. We...

Observations and models have shown that con-tinuously degassing volcanoes have a potentially large ef-fect on the natural background aerosol loading and the ra-diative state of the atmosphere. We use a global aerosol microphysics model to quantify the impact of these vol-canic emissions on the cloud albedo radiative forcing under pre-industrial (PI...

Accurate representation of global stratospheric aerosols from volcanic and non-volcanic sulfur emissions is key to understanding the cooling effects and ozone-losses that may be linked to volcanic activity. Attribution of climate variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the rate of global av...

Historical records show that the A.D. 1783-1784 Laki eruption in Iceland caused severe environmental stress and posed a health hazard far beyond the borders of Iceland. Given the reasonable likelihood of such an event recurring, it is important to assess the scale on which a future eruption could impact society. We quantify the potential health eff...

Relating the mass eruption rate (MER) of explosive eruptions to column height in the atmosphere is key to reconstructing past eruptions and forecasting volcanic hazards. Using 134 eruptive events from the Independent Volcanic Eruption Source Parameter Archive (IVESPA v1.0), we explore the canonical MER-height relationship for four measures of colum...

Aerosol–cloud interactions have a potentially large impact on climate but are poorly quantified and thus contribute a substantial and long-standing uncertainty in climate projections. The impacts derived from climate models are poorly constrained by observations because retrieving robust large-scale signals of aerosol–cloud interactions is frequent...

Volcanic eruptions have long been studied for their wide range of climatic effects. Although global-scale climatic impacts following the formation of stratospheric sulfate aerosol are well understood, many aspects of the evolution of the early volcanic aerosol cloud and regional impacts are uncertain. In the last twenty years, several advances have...

This paper provides initial results from a multi-model ensemble analysis based on the volc-pinatubo-full experiment performed within the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) as part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The volc-pinatubo-full experiment is based on an...

Between 27 June and 14 July 2019 aerosol layers were observed by the United Kingdom (UK) Raman lidar network in the upper troposphere and lower stratosphere. The arrival of these aerosol layers in late June caused some concern within the London Volcanic Ash Advisory Centre (VAAC) as according to dispersion simulations the volcanic plume from the 21...

Aerosol–cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be ch...

Volcanic air pollution from both explosive and effusive activity can affect large populations as far as thousands of kilometers away from the source, for days to decades or even centuries. Here, we summarize key advances and prospects in the assessment of health hazards, effects, risk, and management. Recent advances include standardized ash assess...

This paper provides initial results from a multi-model ensemble analysis based on the volc-pinatubo-full experiment performed within the Model Intercomparison Project on the climatic response to volcanic forcing (VolMIP) as part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The volc-pinatubo-full experiment is based on en...

Volcanic eruptions can cause significant disruption to society, and numerical models are crucial for forecasting the dispersion of erupted material. Here we assess the skill and limitations of the Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME) in simulating the dispersion of the sulfur dioxide (SO2) cloud from the 21–22...

Reconstructions of volcanic aerosol radiative forcing are required to understand past climate variability. Currently, reconstructions of pre-20th century volcanic forcing are derived from sulfate concentrations measured in polar ice cores, mainly using a relationship between the average ice-sheet sulfate deposition and stratospheric sulfate aerosol...

Between 27 June and 14 July 2019 aerosol layers were observed by the United Kingdom (UK) Raman lidar network in the upper troposphere and lower stratosphere. The arrival of these aerosol layers in late June caused some concern within the London Volcanic Ash Advisory Centre (VAAC) as according to dispersion simulations the volcanic plume from the 21...

Eruptive column models are powerful tools for investigating the transport of volcanic gas and ash, reconstructing past explosive eruptions, and simulating future hazards. However, the evaluation of these models is challenging as it requires independent estimates of the main model inputs (e.g. mass eruption rate) and outputs (e.g. column height). Th...

As part of the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP), several climate modeling centers performed a coordinated pre-study experiment with interactive stratospheric aerosol models simulating the volcanic aerosol cloud from an eruption resembling the 1815 Mt. Tambora eruption (VolMIP-Tambora ISA ensemble)....

Significance The Mount Samalas eruption in 1257, one of the largest explosive volcanic eruptions in the Common Era, has proven a complex case for climate models which have generally overestimated the climate response compared with proxy data. Here we perform Earth system model simulations of the impacts of the Mount Samalas eruption using a range o...

Volcanic eruptions can cause significant disruption to society and numerical models are crucial for forecasting the dispersion of erupted material. Here we assess the skill and limitations of the Met Office’s Numerical Atmospheric-dispersion Modelling Environment (NAME) in simulating the dispersion of the sulfur dioxide (SO2) cloud from the 21–22 J...

As part of the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP), several climate modeling centers performed a coordinated pre-study experiment with interactive stratospheric aerosol models simulating the volcanic aerosolcloud from an eruption resembling the 1815 Mt Tambora eruption (VolMIP-Tambora ISA ensemble). T...

Idealized models or emulators of volcanic aerosol forcing have been widely used to reconstruct the spatiotemporal evolution of past volcanic forcing. However, existing models, including the most recently developed Easy Volcanic Aerosol (EVA; Toohey et al., doi: 10.5194/gmd-2016-83), (i) do not account for the height of injection of volcanic SO urn:...

Among the hazards posed by volcanoes are the emissions of gases and particles that can affect air quality and damage agriculture and infrastructure. A recent intense episode of volcanic degassing associated with severe impacts on air quality accompanied the 2018 lower East Rift Zone (LERZ) eruption of Kīlauea volcano, Hawai'i. This resulted in a ma...

Decreases in stratospheric NOx associated with enhanced aerosol have been observed after large volcanic eruptions, for example, after the eruption of Mount Pinatubo in 1991. While the 1991 Mount Pinatubo eruption was the last large explosive eruption, recent studies have shed light on the impacts of moderate-sized eruptions since the year 2000 on t...

Reconstructions of volcanic aerosol radiative forcing are required to understand past climate variability. Currently, reconstructions of pre-20th century volcanic forcing are derived from sulfate concentrations measured in polar ice cores, predominantly using a relationship between average ice sheet sulfate deposition and stratospheric sulfate aero...

The 6-month-long 2014–2015 Holuhraun eruption was the largest in Iceland for 200 years, emitting huge quantities of sulfur dioxide (SO2) into the troposphere, at times overwhelming European anthropogenic emissions. Weather, terrain and latitude made continuous ground-based or UV satellite sensor measurements challenging. Infrared Atmospheric Soundi...

The radiative forcing caused by a volcanic eruption is dependent on several eruption source parameters such as the mass of sulfur dioxide (SO2) emitted, the eruption column height, and the eruption latitude. General circulation models with prognostic aerosol and chemistry schemes can be used to investigate how each parameter influences the volcanic...

Using volcanic sulfur dioxide emissions in an aerosol-climate model, we derive a time series of global-mean volcanic effective radiative forcing (ERF) from 1979 to 2015. For 2005–2015, we calculate a global multiannual mean volcanic ERF of −0.08 W/m² relative to the volcanically quiescent 1999–2002 period, due to a high frequency of small-to-modera...

We demonstrate that identification of stratospheric ozone changes attributable to ozone depleting substances and actions taken under the Montreal Protocol requires evaluation of confounding influences from volcanic eruptions. Using a state-of-the-art chemistry-climate model, we show that increased stratospheric aerosol loading from volcanic eruptio...

The Stratospheric Sulfur and its Role in Climate (SSiRC) Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP) explores uncertainties in the processes that connect volcanic emission of sulfur gas species and the radiative forcing associated with the resulting enhancement of the stratospheric aerosol layer. The central aim of ISA...

We identify flaws in the criticisms of Harning et al. (2018).

As a collaborative activity within the Past Global Changes (PAGES) Volcanic Impacts on Climate and Society (VICS) working group, this work aims to bring together evidence from a wide range of scientific and scholarly disciplines in order to piece together a holistic and unbiased picture of the connections between volcanism and climate in the mid-15...

The six-month-long 2014–2015 Holuhraun eruption was the largest in Iceland for 200 years, emitting huge quantities of sulphur dioxide (SO2) into the troposphere, at times overwhelming European anthropogenic emissions. Weather, terrain and latitude, made continuous ground-based or UV satellite sensor measurements challenging. Infrared Atmospheric So...

Volcanic eruptions impact climate through the injection of sulfur dioxide (SO2), which is oxidized to form sulfuric acid aerosol particles that can enhance the stratospheric aerosol optical depth (SAOD). Besides large-magnitude eruptions, moderate-magnitude eruptions such as Kasatochi in 2008 and Sarychev Peak in 2009 can have a significant impact...

The Stratospheric Sulfur and its Role in Climate (SSiRC) interactive stratospheric aerosol model intercomparison project (ISA-MIP) explores uncertainties in the processes that connect volcanic emission of sulphur gas species and the radiative forcing associated with the resulting enhancement of the stratospheric aerosol layer. The central aim of IS...

We present new insights into the evolution and interactions of stratospheric aerosol using an updated version of the Whole Atmosphere Community Climate Model (WACCM). Improved horizontal resolution, dynamics, and chemistry now produce an internally generated quasi-biennial oscillation and significant improvements to stratospheric temperatures and o...

REFERENCE: If using this resource please reference as: Swindles, G.T., Watson, E.J., Savov, I.P., Cooper, C.L., Lawson, I.T., Schmidt, A. and Carrivick, J.L. 2017. Holocene volcanic ash database for Northern Europe. Database. DOI: 10.13140/RG.2.2.11395.60966. Retrieved from: https://www.researchgate.net/publication/322622249_Holocene_volcanic_ash_...

The Southern Hemisphere Antarctic stratosphere experienced two noteworthy events in 2015: a significant injection of sulfur from the Calbuco volcanic eruption in Chile in April and a record-large Antarctic ozone hole in October and November. Here we quantify Calbuco's influence on stratospheric ozone depletion in austral spring 2015 using observati...

Developing a comprehensive understanding of the interactions between the atmosphere and the geosphere is an ever-more pertinent issue as global average temperatures continue to rise. The possibility of more frequent volcanic eruptions and more therefore more frequent volcanic ash clouds raises potential concerns for the general public and the aviat...

We present new insights into the evolution and interactions of stratospheric aerosol using an updated version of the Whole Atmosphere Community Climate Model (WACCM). Improved horizontal resolution, dynamics, and chemistry now produce an internally generated quasi-biennial oscillation, and significant improvements to stratospheric temperatures and...

Human-induced climate change is causing rapid melting of ice in many volcanically active regions. Over glacial-interglacial time scales changes in surface loading exerted by large variations in glacier size affect the rates of volcanic activity. Numerical models suggest that smaller changes in ice volume over shorter time scales may also influence...

The Southern Hemisphere Antarctic stratosphere experienced two noteworthy events in 2015: a significant injection of sulfur from the Calbuco volcanic eruption in Chile in April and a record-large Antarctic ozone hole in October and November. Here we quantify Calbuco's influence on stratospheric ozone depletion in austral spring 2015 using observati...

This corrects the article DOI: 10.1038/nature22974.

The eruption of Mt. Tambora in 1815 was the largest volcanic eruption of the past 500 years. The eruption had significant climatic impacts, leading to the 1816 year without a summer, and remains a valuable event from which to understand the climatic effects of large stratospheric volcanic sulfur dioxide injections. The eruption also resulted in one...

Aerosols have a potentially large effect on climate, particularly through their interactions with clouds, but the magnitude of this effect is highly uncertain. Large volcanic eruptions produce sulfur dioxide, which in turn produces aerosols; these eruptions thus represent a natural experiment through which to quantify aerosol-cloud interactions. He...

The 2014-2015 Holuhraun eruption in Iceland, emitted ~11 Tg of SO2 into the troposphere over 6 months, and caused one of the most intense and widespread volcanogenic air pollution events in centuries. This study provides a number of source terms for characterisation of plumes in large fissure eruptions, in Iceland and elsewhere. We characterised th...

Recent research has demonstrated that the concentrations of anthropogenic halocarbons have decreased in response to the worldwide phaseout of ozone depleting substances. Yet in 2015 the Antarctic ozone hole reached a historical record daily average size in October. Model simulations with specified dynamics and temperatures based on a reanalysis sug...

Air pollutants, such as ozone, have adverse impacts on human health and cause, for example, respiratory and cardiovascular problems. In the United Kingdom (UK), peak surface ozone concentrations typically occur in the spring and summer and are controlled by emission of precursor gases, tropospheric chemistry and local meteorology which can be influ...

Model simulations presented in this paper suggest that transport processes associated with the summer monsoons bring increased abundances of hydrochloric acid into contact with liquid sulfate aerosols in the cold tropical lowermost stratosphere, leading to heterogeneous chemical activation of chlorine species. The calculations indicate that the spa...

The enhancement of the stratospheric aerosol layer by volcanic eruptions induces a complex set of responses causing global and regional climate effects on a broad range of timescales. Uncertainties exist regarding the climatic re- sponse to strong volcanic forcing identified in coupled cli- mate simulations that contributed to the fifth phase of th...

We present in situ balloon-borne measurements of aerosols in a volcanic plume made during the Holuhraun eruption (Iceland) in January 2015. The balloon flight intercepted a young plume at 8 km distance downwind from the crater, where the plume is ~15 minutes of age. The balloon carried a novel miniature optical particle counter LOAC (Light Optical...

Turning the corner The Antarctic ozone hole is finally showing signs of disappearing, nearly 30 years after the Montreal Protocol came into effect. The Montreal Protocol, an international treaty that phased out the production of many of the human-made compounds responsible for stratospheric ozone destruction, is widely considered to be the most imp...

The SPARC activity, “Stratospheric Sulfur and its Role in Climate” (SSiRC) was initiated to coordinate interna- tional research activities on modelling and observation of stratospheric sulphate aerosols (and precursor gases) in order to assess its climate forcing and feedback. With several international activities to extend and improve observationa...