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Geosciences Column: How erupting African volcanoes impact the Amazon’s atmosphere

Geosciences Column: How erupting African volcanoes impact the Amazon’s atmosphere

When volcanoes erupt, they can release into the atmosphere a number of different gases initially stored in their magma, such as carbon dioxide, hydrogen sulfide, and sulfur dioxide. These kinds of gases can have a big influence on Earth’s atmosphere, even at distances hundreds to thousands of kilometres away.

A team of researchers have found evidence that sulfur emissions from volcanic eruptions in Africa can be observed as far as South America, even creating an impact on the Amazon rainforest’s atmosphere. The results of their study were published last year in the EGU journal Atmospheric Chemistry and Physics.

Amazon Tall Tower Observatory based in the Amazon rainforest of Brazil (Credit: Jsaturno via Wikimedia Commons)

In September 2014, the Amazon rainforest’s atmosphere experienced an unusually sharp spike in the concentration of sulfate aerosols. During this period, the Amazon Tall Tower Observatory (ATTO) based in Brazil reported levels of sulfate never recorded before in the Amazon Basin.

Sulfate aerosols are particles that take form naturally from sulfur dioxide compounds in the atmosphere. When sulfate aerosols spread throughout the atmosphere, the particles often get in the way of the sun’s rays, reflecting the sunlight’s energy back to space. These aerosols can also help clouds take shape. Through these processes, the particles can create a cooling effect on Earth’s climate. Sulfate aerosols can also facilitate chemical reactions that degrade Earth’s ozone layer.

Fossil fuel and biomass burning have been known cause an increase in atmospheric sulfate, but researchers involved in the study found that neither human activity increased the level of sulfate in the atmosphere significantly. Instead, they examined whether a volcanic eruption could be responsible.

Scientists have suggested for some time that sulfur emissions in the Amazon could come from African volcanoes, but until now they’ve lacked proof to properly justify this idea.

Edited Landsat 8 image of the volcanoes Nyamuragira and Nyiragongo in Congo near the city of Goma. (Credit: Stuart Rankin via flickr, NASA Earth Observatory images by Jesse Allen, using Landsat data from the U.S. Geological Survey.

However, in this study the research team involved caught volcanic pair in the act. By analysing satellite images and aerosol measurements, the researchers found evidence that in 2014, emissions from the neighboring Nyiragongo-Nyamuragira volcano complex in the Democratic Republic of the Congo, central Africa, increased the level of sulfate particles in the Amazon rainforest’s atmosphere.

Satellite observations revealed that volcanoes experienced two explosive events in September 2014, releasing sulfur emissions into the atmosphere. During that year, the volcanic complex was reportedly subject to frequent eruptive events, sending on average 14,400 tonnes of sulfur dioxide into the atmosphere a day during such occasions. This amount of gas would weigh more than London’s supertall Shard skyscraper.

Map of SO2 plumes with VCD > 2.5 × 1014 molecules cm−2 color-coded by date of observation. The 15-day forward trajectories started at 4 km (above mean sea level, a.m.s.l.) at four locations within the plume detected on 13 September 2014 (light blue) are indicated by black lines with markers at 24 h intervals. (Credit: Jorge Saturno et al.)

The images further show that these emissions were transported across the South Atlantic Ocean to South America. The sulfate particles created from the emissions were then eventually picked up by an airborne atmospheric survey campaign and the ATTO in the Amazon.

The researchers of the study suggest that these observations indicate that African volcanoes can have an effect on the Amazon Basin’s atmosphere, though more research is needed to understand the full extent of this impact.

By Olivia Trani, EGU Communications Officer

References and further reading

Volcanic gases can be harmful to health, vegetation and infrastructure. Volcano Hazards Program. USGS.

Aerosols and Incoming Sunlight (Direct Effects). NASA Earth Observatory

Saturno, J., Ditas, F., Penning de Vries, M., Holanda, B. A., Pöhlker, M. L., Carbone, S., Walter, D., Bobrowski, N., Brito, J., Chi, X., Gutmann, A., Hrabe de Angelis, I., Machado, L. A. T., Moran-Zuloaga, D., Rüdiger, J., Schneider, J., Schulz, C., Wang, Q., Wendisch, M., Artaxo, P., Wagner, T., Pöschl, U., Andreae, M. O. and Pöhlker, C.: African volcanic emissions influencing atmospheric aerosols over the Amazon rain forest, Atmospheric Chemistry and Physics, 18(14), 10391–10405, doi:10.5194/acp-18-10391-2018, 2018.

Imaggeo on Mondays: Science above the Amazon rainforest

Imaggeo on Mondays: Science above the Amazon rainforest

The color and symmetry of the Amazon Tall Tower Observatory (ATTO) sticks out against the endless green of the rainforest. Built in a remote and pristine location, the ATTO tower is the tallest construction in South America. In a joint Brazilian-German project, atmospheric scientists aim to unravel the interaction of pristine rainforest with the atmosphere. With its height of 325 meters, the ATTO tower allows for studying atmospheric processes at different spatial scales.

Description by Achim Edtbauer, as it first appeared on imaggeo.egu.eu.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: A pink and blue evening

Imaggeo on Mondays: A pink and blue evening

At sunset, the light travels a longer path in the atmosphere to reach our eyes than when the sun is high in the sky. At this time of the day, the light is more subject to scattering, as it interacts with more air (molecules and particles) before reaching our eyes, which explains why the sun is much less luminous and can be observed directly without being dazzled.

The sun appears redder because among the visible colours it emits, the blue radiation has been scattered by air molecules before this blue light reaches the observer. Indeed, the Rayleigh scattering theory says that the blue light (wavelength near 400 nm) is 16 times more scattered than the red light (wavelength near 800 nm). So the blue light is deviated outside the sun direction and only the remaining red light reaches the observer looking in the sun direction. This phenomenon also gives the blue colour of the sky when we look elsewhere than the direction of the sun.

Clouds consist of particles of liquid or solid water that are much larger than air molecules. It is then the Mie scattering theory that applies. This scattering favors no colour, which explains the milky colour of the clouds during the day. The clouds have the same colour of the solar radiation that strikes them. They therefore take a red colour at sunset and sunrise.

The night I took this photo, the beauty of the show was tinged with sadness: I came to the Pic du Midi Observatory in the Pyrenees (2800 m altitude) to observe the stars, not the clouds! This night of stars observation was a very great birthday present from my lab colleagues.

Luckily, the ceiling of the cloud layer lowered a little and the night was clear enough. The next morning, at dawn, the sea of ​​clouds confined in the valleys also offered a grandiose spectacle.

By Claudine Vanbauce, Université de Lille, Laboratoire d’Optique Atmosphérique, France

If you pre-register for the 2019 General Assembly (Vienna, 07–12 April), you can take part in our annual photo competition! From 15 January until 15 February, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

October GeoRoundUp: the best of the Earth sciences from around the web


Carbon dioxide plays a significant role in trapping heat in Earth’s atmosphere. The gas is released from human activities like burning fossil fuels, and the concentration of carbon dioxide moves and changes through the seasons. Using observations from NASA’s Orbiting Carbon Observatory (OCO-2) satellite, scientists developed a model of the behavior of carbon in the atmosphere from Sept. 1, 2014, to Aug. 31, 2015. Scientists can use models like this one to better understand and predict where concentrations of carbon dioxide could be especially high or low, based on activity on the ground. Credit: NASA’s Goddard Space Flight Center/K. Mersmann, M. Radcliff, producers

Drawing inspiration from popular stories on our social media channels, as well as unique and quirky research news, this monthly column aims to bring you the best of the Earth and planetary sciences from around the web.

Major story

Our top pick for October is a late breaking story which made headlines across news channels world-wide. The World Meteorological Organization (WMO) announced that ‘Greenhouse gases in the atmosphere had surged to new records’ in 2016.

“Globally averaged concentrations of CO2 reached 403.3 parts per million in 2016, up from 400.00 ppm in 2015 because of a combination of human activities and a strong El Niño event,” reported the WMO in the their press release.

The last time Earth experienced a comparable concentration of CO2 was 3 to 5 million years ago (around the period of the Pliocene Epoch), when temperatures were 2-3°C warmer and sea level was 10-20 meters higher than now. You can put that into context by taking a look at this brief history of Earth’s CO2 .

Rising levels of atmospheric CO2  present a threat to the planet, most notably driving rising global temperatures. The new findings compromise last year’s Paris Climate Accord, where 175 nations agreed to work towards limiting the rise of global temperatures by 1.5 degrees celsius (since pre-industrial levels).

No doubt the issue will be discussed at the upcoming COP 23 (Conference of Parties), which takes place in Bonn from 6th to 17th of November in Bonn. Fiji, a small island nation particularly vulnerable to rising sea levels and extreme weather phenomena (a direct result of climate change), is the meeting organiser.

What you might have missed

The 2017 Hurricane season has been devastating (as we’ve written about on the blog previously), but in a somewhat unexpected turn of events, one of the latest storms to form over the waters of the Atlantic, took a turn towards Europe.

Storm Ophelia formed in waters south-west of the Azores, where the mid-latitude jet stream push the storm toward the UK and Ireland. By the time it made landfall it had been downgraded to a tropical storm, but was still powerful enough to caused severe damage. Ireland, battered by 160 kmph winds, declared a national emergency following the deaths of three people.

NASA-NOAA’s Suomi NPP satellite took this thermal image of Hurricane Ophelia over Ireland on Oct. 16 at 02:54 UTC (Oct. 15 at 10:54 p.m. EDT).
Credits: NOAA/NASA Goddard Rapid Response Team

The effects of the storm weren’t only felt across the UK and Ireland. In the wake of an already destructive summer fire season, October brought further devastating forest fires to the Iberian Peninsula. The blazes claimed 32 victims in Portugal and 5 in Spain. Despite many of the wildfires in Spain thought to have been provoked by humans, Ophelia’s strong winds fanned the fire’s flames, making firefighter’s efforts to control the flames much more difficult.

On 16th October many in the UK woke up to eerie red haze in the sky, which turned the Sun red too. The unusual effect was caused by Ophelia’s winds pulling dust from the Sahara desert northward, as well as debris and smoke from the Iberian wildfires.

And when you thought it wasn’t possible for Ophelia to become more remarkable, it also turns out that it became the 10th storm of 2017 to reach hurricane strength, making this year the fourth on record (and the first in over a century) to hit that milestone.

But extreme weather wasn’t only limited to the UK and Ireland this month. Cyclone Herwart brought powerful winds to Southern Denmark, Germany, Poland, Hungary and Czech Republic over the final weekend of October. Trains were suspended in parts of northern Germany and thousands of Czechs and Poles were left without power. Six people have been reported dead. Hamburg’s inner city area saw significant flooding, while German authorities are closely monitoring the “Glory Amsterdam”, a freighter laden with oil, which ran aground in the North Sea during the storm. A potential oil spillage, if the ship’s hull is damaged, is a chief concern, as it would have dire environmental concerns for the Wadden Sea (protected by UNESCO).

Links we liked

The EGU story

This month we released not one but two press releases from research published in our open access journals. The finding of both studies have important societal implications. Take a look at them below

Deforestation linked to palm oil production is making Indonesia warmer

In the past decades, large areas of forest in Sumatra, Indonesia have been replaced by cash crops like oil palm and rubber plantations. New research, published in the European Geosciences Union journal Biogeosciences, shows that these changes in land use increase temperatures in the region. The added warming could affect plants and animals and make parts of the country more vulnerable to wildfires.

Study reveals new threat to the ozone layer

“Ozone depletion is a well-known phenomenon and, thanks to the success of the Montreal Protocol, is widely perceived as a problem solved,” says University of East Anglia’s David Oram. But an international team of researchers, led by Oram, has now found an unexpected, growing danger to the ozone layer from substances not regulated by the treaty. The study is published in Atmospheric Chemistry and Physics, a journal of the European Geosciences Union.