Henrik Svensmark (born 1958) is a Danish physicist and professor in the Division of Solar System Physics at the Danish National Space Institute (DTU Space) in Copenhagen. He is known for his work on the hypothesis that fewer cosmic rays are an indirect cause of global warming via cloud formation.
Early life and education Henrik Svensmark obtained a Master of Science in Engineering (Cand. Polyt) in 1985 and a Ph.D. in 1987 from the Physics Laboratory I at the Technical University of Denmark.
Career
Henrik Svensmark is director of the Center for Sun-Climate Research at the Danish Space Research Institute (DSRI), a part of the Danish National Space Center. He previously headed the sun-climate group at DSRI. He held postdoctoral positions in physics at three other organizations: University of California, Berkeley, Nordic Institute for Theoretical Physics, and the Niels Bohr Institute. In 1997, Svensmark and Eigil Friis-Christensen popularised a theory that linked galactic cosmic rays and global climate change mediated primarily by variations in the intensity of the solar wind, which they have termed cosmoclimatology. This theory had earlier been reviewed by Dickinson. One of the small-scale processes related to this link was studied in a laboratory experiment performed at the Danish National Space Center (paper published in the Proceedings of the Royal Society A, February 8, 2007). Svensmark's conclusions from his research downplay the significance of the effects of man-made increases in atmospheric CO2 on recent and historical global warming, with him arguing that while the climate change role of greenhouse gases is considerable, solar variations play a larger role.
Cosmoclimatology theory of climate change Svensmark detailed his theory of cosmoclimatology in a paper published in 2007. The Center for Sun-Climate Research at the Danish National Space Institute "investigates the connection between solar activity and climatic changes on Earth". Its homepage lists several publications earlier works related to cosmoclimatology. Svensmark and Nigel Calder published a book The Chilling Stars: A New Theory of Climate Change (2007) describing the Cosmoclimatology theory that cosmic rays "have more effect on the climate than manmade CO2":
"During the last 100 years cosmic rays became scarcer because unusually vigorous action by the Sun batted away many of them. Fewer cosmic rays meant fewer clouds—and a warmer world." Scientists have generally not found the published work of Svensmark et al. persuasive. For example, Lockwood et al. find that "The cloud-cosmic ray suggestion increasingly fails to match observations". A joint Spanish/Japanese collaboration of solar ray/astrophysics experts found that the change in global cloud cover is closely correlated with El Niño–Southern Oscillation and uncorrelated with solar rays. A documentary film on Svensmark's theory, The Cloud Mystery, was produced by Lars Oxfeldt Mortensen and premiered in January 2008 on Danish TV 2. In April 2012, Svensmark published an expansion of his theory in the Monthly Notices of the Royal Astronomical Society In the new work he claims that the diversity of life on Earth over the last 500 million years might be explained by tectonics affecting the sea-level together with variations in the local supernova rate, and virtually nothing else. This suggests that the progress of evolution is affected by climate variation depending on the galactic cosmic ray flux. The director of DTU Space, Prof. Eigil Friis-Christensen, commented: "When this enquiry into effects of cosmic rays from supernova remnants began 16 years ago, we never imagined that it would lead us so deep into time, or into so many aspects of the Earth's history. The connection to evolution is a culmination of this work."
Hypothesis tests Preliminary experimental tests have been conducted in the SKY Experiment at the Danish National Space Science Center. CERN, the European Organization for Nuclear Research in Geneva, is preparing comprehensive verification in the CLOUD Project.
SKY Experiment Svensmark conducted proof of concept experiments in the SKY Experiment at the Danish National Space Institute.
To investigate the role of cosmic rays in cloud formation low in the Earth's atmosphere, the SKY experiment used natural muons (heavy electrons) that can penetrate even to the basement of the National Space Institute in Copenhagen. The hypothesis, verified by the experiment, is that electrons released in the air by the passing muons promote the formation of molecular clusters that are building blocks for cloud condensation nuclei. Critics of the hypothesis claimed that particle clusters produced measured just a few nanometres across, whereas aerosols typically need to have a diameter of at least 50 nm in order to serve as so-called cloud condensation nuclei. Further experiments by Svensmark and collaborators published in 2013 showed that aerosols with diameter larger than 50 nm are produced by ultraviolet light (from trace amounts of ozone, sulfur dioxide, and water vapor), large enough to serve as cloud condensation nuclei.
CLOUD Project Experiments
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