Now this is a hoot:
Did lead cause global cooling?
Letter abstract
Nature Geoscience 2, 333 - 336 (2009)
Published online: 19 April 2009 | doi:10.1038/ngeo499
There is an Erratum (21 May 2009) associated with this Letter.
Subject Category: Atmospheric science
Inadvertent climate modification due to anthropogenic lead
Daniel J. Cziczo1,2, Olaf Stetzer2, Annette Worringen3, Martin Ebert3, Stephan Weinbruch3, Michael Kamphus4, Stephane J. Gallavardin2,4, Joachim Curtius4,5, Stephan Borrmann4,6, Karl D. Froyd7, Stephan Mertes8, Ottmar Möhler9 & Ulrike Lohmann2
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Aerosol particles can interact with water vapour in the atmosphere, facilitating the condensation of water and the formation of clouds. At temperatures below 273 K, a fraction of atmospheric particles act as sites for ice-crystal formation. Atmospheric ice crystals—which are incorporated into clouds that cover more than a third of the globe1—are thought to initiate most of the terrestrial precipitation2. Before the switch to unleaded fuel last century, the atmosphere contained substantial quantities of particulate lead; whether this influenced ice-crystal formation is not clear. Here, we combine field observations of ice-crystal residues with laboratory measurements of artificial clouds, to show that anthropogenic lead-containing particles are among the most efficient ice-forming substances commonly found in the atmosphere3. Using a global climate model, we estimate that up to 0.8 W m-2 more long-wave radiation is emitted when 100% of ice-forming particles contain lead, compared with when no particles contain lead. We suggest that post-industrial emissions of particulate lead may have offset a proportion of the warming attributed to greenhouse gases.
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1. Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, Washington 99354, USA
2. Institute for Atmospheric and Climate Science, ETH Zurich, Universitätstrasse 16, CH-8092 Zürich, Switzerland
3. Institute for Applied Geosciences, Technical University Darmstadt, Schnittspahnstras zlige 9, D-64287 Darmstadt, Germany
4. Institute for Atmospheric Physics, Johannes Gutenberg-University of Mainz, Joh.-Joachim-Becher-Weg 21, D-55099 Mainz, Germany
5. Institute for Atmospheric and Environmental Sciences, Goethe-University Frankfurt am Main, Altenhöferallee 1, D-60438 Frankfurt am Main, Germany
6. Particle Chemistry Department, Max Planck-Institute for Chemistry, D-55128 Mainz, Germany
7. Chemical Sciences Division, National Oceanic and Atmospheric Administration, 325 Broadway Ave., Boulder, Colorado 80305, USA
8. Leibniz-Institute for Tropospheric Research, D-04318 Leipzig, Germany
9. Institute for Meteorology and Climate Research, Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe, Germany