Volcanic aerosols have acted as a natural umbrella to slow down global temperature increase from greenhouse gases.
Although global concentrations of greenhouse gases in the atmosphere have continuously increased over the past decade, the mean global surface temperature has not followed the same path. While this slow down in global warming is not fully understood, a team of international reseachers have now found an explanation: the incoming solar radiation in the years 2008-2011 was twice as much reflected by volcanic aerosol particles in the lowest part of the stratosphere than previously thought.
The IAGOS-CARIBIC air inlet system mounted at the IAGOS-CARIBIC Airbus.
Source: Deutsche Lufthansa AG
According to a study in Nature Communications, the cooling effect due to volcanic eruptions was clearly underestimated by climate models used for the last Intergovernmental Panel on Climate Change (IPCC) report. Led by the University of Lund, Sweden, and supported by the NASA Langley Research Center, USA, and the Royal Netherlands Meteorological Institute, three major German atmospheric research institutes were also involved: the Max Planck Institute for Chemistry in Mainz (MPI-C), the Leibniz Institute for Tropospheric Research in Leipzig (TROPOS) and the Karlsruhe Institute of Technology (KIT).
Since volcanic eruptions are unpredictable, additional cooling may or may not continue in the next few years. On the long-term the temperature increase caused by the greenhouse gases will dominate over the cooling effect caused by volcanic eruptions, because the greenhouse gas concentrations are still continuously increasing.
In the first decade of the 21st century the average surface temperature over the northern mid-latitude continents did not increase. This effect was intensively discussed in the scientific community and can be now explained by the new study on volcanic aerosol particles in the atmosphere reported here. The study uses data from the tropopause region up to 35 km altitude, where the former is found between 8 km (poles) and 17 km (equator) altitude.
The tropopause region is a transition region between the underlying wet weather layer with its clouds (the troposphere) and the dry and cloud-free layer above (the stratosphere). The analysis could be realized when the team combined two different experimental approaches: sampling and in situ measurements made by IAGOS-CARIBIC together with observations from the CALIPSO satellite.
In the CARIBIC project (www.caribic-atmospheric.de) trace gases and aerosol particles in the tropopause region are measured since 1997. A modified air-freight container is loaded once per month for four intercontinental flights into a modified Airbus A340-600 of Lufthansa. Altogether about 100 trace gas and aerosol parameters are measured in situ at 9-12 km altitude as well as in dedicated research laboratories after flight. CARIBIC thus constitutes a crucial cornerstone of the worldwide atmospheric monitoring network for a better understanding of atmospheric processes and climate change.
TROPOS is responsible for the in situ aerosol particle measurements in this unique project. Collected particles are analyzed at the University of Lund, Sweden, using an ion beam accelerator for measuring the amount of particulate sulfur. When comparing this particulate sulfur concentration to the in situ measured ozone concentration this ratio is usually quite constant at cruise altitude. However, volcanic eruptions increase the amount of particulate sulfur and thus the ratio becomes an indicator of volcanic eruption influencing the tropopause region.
„The ratio of particulate sulfur to ozone from the CARIBIC measurements clearly demonstrates the strong influence from volcanism on the tropopause region”, reports Dr. Sandra M. Andersson and Prof. Bengt G. Martinsson of the University of Lund, who are the lead authors.
The second method is based on satellite observations. The Cloud-Aerosol Lidar and Pathfinder Satellite Observation (CALIPSO) mission, a collaboration between the National Aeronautics and Space Administration (NASA) in the US and the Centre National d’Etude Spatiale (CNES) in France, has provided unprecedented view on aerosol and cloud layers in the atmosphere. Until recently, the data had only been scrutinized where volcanic aerosols are known to affect our climate for a long time, above 15 km.
The forgotten region of the stratosphere, also called the lowermost stratosphere, has now been fully taken into account to evaluate the impact of smaller volcanic eruptions on the climate. “Dr. Sandra Andersson, former PhD student working with Prof. Martinsson has done a really great job in digging into the CALIPSO data to search for the missing layers” said Dr. Jean-Paul Vernier from NASA Langley Research Center, USA.
The influence from volcanic eruptions on the stratosphere was small in the northern hemisphere between 1999 and 2002. However, strong signals of volcanic aerosol particles were observed between 2005 and 2012. In particular three eruptions stand out: the Kasatochi in August 2008 on the Aleutian Islands in Alaska (USA), the Sarychev in June 2009 on the Kuril Islands near Kamchatka (Russia) and the Nabro in June 2011 in Eritrea at the Red Sea. Each of the three eruptions injected more than one megaton of sulfur dioxide (SO2) into the atmosphere. „Virtually all volcanic eruptions reaching the stratosphere lead to more particles there, as they bring in sulfur dioxide, which is converted to sulfate particles“, explains Dr. Markus Hermann of TROPOS, who conducts the in situ particle measurements in CARIBIC.
Whether a volcanic eruption has a global climate impact or not depends on several factors. There is the amount of volcanic sulfur dioxide as well as the injection height. But also the latitude of the eruption is important: As the air flow in northern hemispheric stratosphere is largely disconnected from the southern hemisphere, only volcanic eruptions near the equator can effectively distribute the emitted material over both hemispheres. In April 2015 the scientific community commemorated the Tambora eruption on the Indonesian Island Sumbawa (8° northern latitude) 200 years ago.
This eruption led to such a strong global cooling that the year 1816 was called „year without summer“, including worldwide crop failures and famines. Also the Krakatau eruption 1883 on Indonesia (6° southern latitude) or the Pinatubo 1991 on the Philippines (15° northern latitude) led to noticeable cooling. The present study now indicates that „the cooling effect of volcanic eruptions was underestimated in the past, because the lowest part of the stratosphere was mostly not considered. Interestingly our results show that the effect also depends on the season.
The eruptions investigated by us had their strongest impact in late summer when the incoming solar radiation is still strong“, explains Dr. Sandra M. Andersson. „Overall our results emphasize that the lower stratosphere is more important for the Earth´s climate than expected“, summarize Dr. Carl Brenninkmeijer, MPI-C, and Dr. Andreas Zahn, KIT, unanimously, both CARIBIC coordinators. The CARIBIC observatory was coordinated and operated by the MPI-C until the end of 2014, since then by KIT.
In recent years there has been much discussion about the differences between the modeled and the actually observed warming rates, both on systematic errors in the dependence of the climate on the greenhouse gases increase and on problems to represent the natural fluctuations of the climate realistically in the models. Recent studies have shown that changes in ocean currents, variations in solar activity and also aerosols from volcanoes probably contributed to these differences. Susan Solomon and colleagues had estimated in Science (2011) that the radiative effect of volcanic aerosols in the stratosphere above 15 kilometers altitude is about -0.1 watts per square meter. The new study, however now confirms that the global radiative forcing increases by more than 30% in the period between 2008 and 2011, when the lower stratosphere below 15 kilometers altitude is taken into account. At northern mid-latitudes this effect is even much stronger.
Tilo Arnhold (TROPOS)
Sandra M. Andersson, Bengt G. Martinsson, Jean-Paul Vernier, Johan Friberg, Carl A. M. Brenninkmeijer, Markus Hermann, Peter F. J. van Velthoven & Andreas Zahn (2015): Significant radiative impact of volcanic aerosol in the lowermost stratosphere. Nature Communications, doi: 10.1038/ncomms8692.
The research was funded by the German Federal Ministry of Education and Research (BMBF; financing the instruments operation of IAGOS-D) and the German Research Foundation (DFG; Priority Programme HALO/SPP 1294). The Deutsche Lufthansa AG (CARIBIC-Observatory) and the NASA Langley Research Center (aerosol measurements by CALIPSO) support the study.
Dr. Markus Hermann
Leibniz Institute for Tropospheric Research (TROPOS)
Dr. Sandra M. Anderson/ Prof. Bengt G. Martinsson
Lund University (Sweden)
Dr. Andreas Zahn
Institute of Meteorology and Climate Research (IMK) at the Karlsruhe Institute of Technology (KIT)
Phone +49-721-608- 22788
Tilo Arnhold, TROPOS Public Relations
Aerosol Particle Measurements Using Passenger Aircraft - the IAGOS-CARIBIC Project
Particulate Carbon and Sulfur in the Lowermost Stratosphere
IAGOS project: airborne climate research laboratory installed on second Lufthansa Airbus http://www.lufthansagroup.com/en/themen/climate-research.html
Current map of IAGOS flights:
Validation of Satellite-Lidar-Measurements
Effects of aerosol particles on the climate:
„Year Without a Summer“
Aerosols: Tiny Particles, Big Impact
Important scientific publications on the subject:
Karl, T. et al. Science (2015).
Schmidt, G., Shindell, D. T. & Tsigaridis, K. Nature Geosci. 7, 158–160 (2014).
Santer, B. D. et al. Nature Geosci. 7, 185–189 (2014).
Solomon, S. et al. Science 333 (6044), 866-870. (2011).
The Leibniz Association connects 89 independent research institutions that range in focus from the natural, engineering and environmental sciences via economics, spatial and social sciences to the humanities. Leibniz Institutes address issues of social, economic and ecological relevance. They conduct knowledge-driven and applied basic research, maintain scientific infrastructure and provide research-based services. The Leibniz Association identifies focus areas for knowledge transfer to policy-makers, academia, business and the public. Leibniz Institutes collaborate intensively with universities – in the form of “WissenschaftsCampi” (thematic partnerships between university and non-university research institutes), for example – as well as with industry and other partners at home and abroad. They are subject to an independent evaluation procedure that is unparalleled in its transparency. Due to the institutes’ importance for the country as a whole, they are funded jointly by the Federation and the Länder, employing some 18,100 individuals, including 9,200 researchers. The entire budget of all the institutes is approximately 1.64 billion EUR. http://www.leibniz-association.eu
Tilo Arnhold | Leibniz-Institut für Troposphärenforschung e. V.
Research sheds new light on forces that threaten sensitive coastlines
24.04.2017 | Indiana University
NASA sees the end of ex-Tropical Cyclone 02W
21.04.2017 | NASA/Goddard Space Flight Center
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Life Sciences
24.04.2017 | Earth Sciences
24.04.2017 | Machine Engineering