Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Clouds and climate in the pre-industrial age

30.05.2016

Aerosol particles generated by human activity counteract the warming of the earth's atmosphere by greenhouse gases. However, this effect might be smaller than first thought, as many particles were already generated from tree emissions in pre-industrial times. This was the finding of a simulation carried out as part of the international CLOUD experiment, in which researchers from the Goethe University played a major role. The results are published in the form of three papers in the renowned journals "Science" and "Nature".

"These results are the most important so far by the CLOUD experiment at CERN", said CLOUD spokesperson Jasper Kirkby, Honorary Professor at the Goethe University. "When the nucleation and growth of pure biogenic aerosol particles is included in climate models, it should sharpen our understanding of the impact of human activities on clouds and climate."


Mario Simon (from left zu right), Martin Heinritzi, Andreas Kürten, Andrea Wagner und Joachim Curtius mit dem von ihnen entwickelten Massenspektrometer.

Uwe Dettmar

Professor Joachim Curtius from the Institute for Atmospheric and Environmental Sciences at the Goethe University added: "We believe that the newly discovered process will mean that we will have to reassess cloud formation in earlier times, as there must have been more particles present than we had previously assumed. There would therefore be less of a difference between the situation then and now than previously thought."

The CLOUD experiment is looking at how new aerosol particles form in the atmosphere and their effect on climate. As the aerosol particles increase, as is the case due to human activities, more sunlight is reflected and more cloud droplets form, making the clouds brighter.

In order to estimate the cooling effect caused by anthropogenic influences, it is necessary to know the quantities of aerosols present in the pre-industrial age. As direct measurement is not an option, the effects are simulated through reliable laboratory tests such as the CLOUD experiment, and then applied to climate modelling.

In pre-industrial times, the organic compounds emitted by trees were a major contributing factor in the formation of aerosols. The researchers examined alpha-pinene, a substance that gives pine forests their characteristic pleasant smell. They are among the most important biogenic emissions. Alpha-pinene is rapidly oxidised on exposure to ozone and the ensuing reaction chains create some extremely low-volatility substances. However, these only occur in very small concentrations of around one molecule per one trillion air molecules.

The CLOUD experiments show that these extremely low-volatility organic compounds are very efficient at forming new particles. This process occurs under atmospheric conditions, even in the absence of sulphuric acid. It had been assumed that sulphuric acid was virtually always involved in particle formation in the atmosphere. The main source of sulphuric acid in the atmosphere is sulphur dioxide, which is generated by the burning of fossil fuels.

Furthermore, the researchers discovered that ions from cosmic rays strongly enhance the production rate of the organic particles - by a factor of 10-100 compared to particle formation without ions, provided the concentrations of the particle-forming gases are low.

"Furthermore, our studies show that these low-volatility organic substances also dominate particle growth in unpolluted environments across the entire size range from clusters of just a few molecules all the way up to sizes of 50-100 nm, where the particles are large enough to be able to seed cloud droplets", explained Joachim Curtius. The growth rates accelerate as the particles increase in size, because more and more oxidation products, also those of higher volatility, are able to condense on the expanding particles. This process is described in quantitative terms with a condensation model for the various organic substances.

Why is this knowledge important for our understanding of the climate? This may well be a very important mechanism, because it is so efficient in terms of the formation of organic particles under natural conditions. As soon as the particles have formed, they grow through the condensation of other similar oxygenated organic compounds. The rapid growth of the newly-formed particles means that they lose a smaller percentage through collisions with pre-existing large particles. As a result more particles grow to sizes that have the potential to seed clouds and influence the climate.

Another paper that appears in the same issue of "Science" reports on observations from the observatory on the Jungfraujoch, which detected pure organic nucleation in the free troposphere. This proves the relevance of the CLOUD laboratory experiments for the atmosphere.

Weitere Informationen:

https://cds.cern.ch/record/2155289
https://cds.cern.ch/record/2154271

Dr. Anke Sauter | idw - Informationsdienst Wissenschaft

More articles from Earth Sciences:

nachricht NASA's AIM observes early noctilucent ice clouds over Antarctica
05.12.2016 | NASA/Goddard Space Flight Center

nachricht GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

IHP presents the fastest silicon-based transistor in the world

05.12.2016 | Power and Electrical Engineering

InLight study: insights into chemical processes using light

05.12.2016 | Materials Sciences

High-precision magnetic field sensing

05.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>