Lead pollution in the air stimulates the formation of ice particles in clouds.
A team of scientists from the USA, Germany and Switzerland has found that particles containing lead are excellent seeds for the formation of ice crystals in clouds. This not only has a bearing on the formation of rain and other forms of precipitation but may also have an influence on the global climate.
This is because the heat given off from the earth's surface is more efficiently radiated into space by ice clouds (cirrus) with lead-containing particles than has been hitherto realized. In comparison to clouds with a low lead content, clouds with a high lead content thus actually help cool the earth. Over the last twenty years, there has been a continuing decrease in the rate of anthropogenic lead emissions. This may mean that the greenhouse effect is now even more pronounced because lead-containing clouds once previously helped limit it.
At the Sphinx Observatory, a Swiss research station on the Jungfraujoch at an altitude of 3,580 meters, scientists from various institutions, including the Universities of Frankfurt and Mainz, and the Max Planck Institute for Chemistry in Mainz, investigated the chemical composition of clouds in the winters of 2006 and 2007. "What mainly interested us was the question of how ice particles form. Water particles in the atmosphere do not simply freeze at zero degrees. On the contrary, at temperatures as low as minus 37 degrees they still need an ice nucleus, for example an aerosol particle, before ice formation is triggered," explains Professor Joachim Curtius of the Institute for Atmosphere and Environment (IAU) at the Goethe University Frankfurt. The same principle is also employed for snow guns, and in this case proteins derived from Pseudomonas bacteria are sometimes used as the ice-forming nuclei - a controversial application.
Scientists attach a lot of importance to the presence of ice particles in clouds, as they make a vital contribution to the genesis of rain drops within clouds. "Until we know what kinds of particles trigger ice formation in the atmosphere we will not be able to understand climatic change or the global hydrological cycle," comments Professor Stephan Borrmann. The atmospheric physicist is the head of the "Department of Particle Chemistry," a joint venture of the Max Planck Institute for Chemistry and the Institute for Atmospheric Physics at Johannes Gutenberg University Mainz.
Investigations conducted on the Swiss Jungfraujoch and in the Rocky Mountains in Colorado have found that particles that contain lead are among the most effective ice nuclei to be found in the atmosphere. "What was really new for us was the remarkable frequency with which we found lead in the ice particles," says Curtius. "We were able to identify lead in around every second ice nucleus while only one in twenty of the average aerosol particles contained lead." However, lead on its own is not enough to form an ice nucleus. Minute lead particles combine with other constituents of the air, such as mineral dust from the Sahara. Some of these mineral dust particles can themselves act as ice nuclei. Once combined with lead, however, a good ice nucleus becomes an outstanding ice nucleus that is able to initiate ice crystallization at higher temperatures and at lower humidities.
Laboratory experiments at the AIDA Aerosol and Cloud Chamber at the Karlsruhe Research Center have confirmed the results of the field studies in Switzerland. Furthermore, model calculations by the Swiss Federal Institute of Technology Zurich show that lead-containing particles change the properties of cirrus clouds so that these significantly influence the extent to which long-wave radiation escapes from the earth into space. If all ice-forming mineral particles contained lead, the heat emitted by the earth could theoretically be as much as 0.8 watts per square meter. By way of comparison: The climate forcing generated as a result of anthropogenic CO2 emissions is equivalent to roughly 1.6 watts per square meter. The lead-containing ice nuclei thus presumably have a cooling effect on the climate due to their indirect influence on ice cloud formation.
Scientists now assume that as a result of the significantly higher levels of lead pollution in the 1970s and 1980s - resulting from the use of leaded petrol and due to lead emissions from power stations - the great majority of all mineral dust particles were contaminated with lead and as a result more heat escaped from the earth than at present. "This probably led to global inhibition of rises in temperature to some extent, whereas today almost the full greenhouse effect is kicking in," says Curtius.
But a return to the lead emission levels of the late 20th century is hardly desirable. Lead is a toxic heavy metal that can cause severe damage to health. "However, with the benefit of hindsight we can now explain why there has been a trend towards more rapid temperature rises in recent years; it is because mankind has cut back its emissions of lead and sulphates," claims Borrmann.
"These results show that anthropogenic emissions can influence ice nuclei precipitation and, as a result, change precipitation and the climate," to quote the research results published in Nature Geoscience. Among the institutions participating in the project were Technische Universität Darmstadt, the Leibniz Institute for Tropospheric Research in Leipzig, the Pacific Northwest National Laboratory in Richland/Washington, and the U.S. government agency, the National Oceanic and Atmospheric Administration in Boulder/Colorado. Mainz and Frankfurt Universities, Technische Universität Darmstadt ?and the Max Planck Institute for Chemistry participated in the project within the context of the Collaborative Research Center 641 "The tropospheric ice phase" funded by the German Research Foundation (DFG).Original publication:
Petra Giegerich | idw
Further reports about: > Atmospheric > CHEMISTRY > CO2 emissions > Cirrus > Geoscience > Global Climate > Lead pollution > Max Planck Institute > Nature Immunology > aerosol particles > anthropogenic CO2 emissions > formation of ice crystals > greenhouse effect > greenhouse effect in the past > ice clouds > ice formation in clouds > ice nucleus > ice particles in clouds > ice-forming mineral particles > tropospheric ice phase
Sediment from Himalayas may have made 2004 Indian Ocean earthquake more severe
26.05.2017 | Oregon State University
Devils Hole: Ancient Traces of Climate History
24.05.2017 | Universität Innsbruck
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy