| Henrik Svensmark | |
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Henrik Svensmark
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| Born | 1958 |
| Nationality | Danish |
| Fields | Physicist |
| Institutions | Danish Space Research Institute (DSRI) at Danish National Space Center at Technical University of Denmark |
| Notable awards | Energy-E2 Research Prize Knud Hojgaard Anniversary Research Prize |
Henrik Svensmark (born 1958) is a physicist at the Danish National Space Center in Copenhagen who studies the effects of cosmic rays on cloud formation. His work presents hypotheses about solar activity as an indirect cause of global warming; his research has suggested a possible link through the interaction of the solar wind and cosmic rays. His conclusions have been controversial as the prevailing scientific opinion on climate change considers solar activity unlikely to be a major contributor to recent warming,[1] though it is thought to be the primary driver of many earlier changes in climate.
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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.[2]
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.[3] 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 research downplays the significance to which atmospheric CO2 has affected recent global warming.
Svensmark detailed his theory of cosmoclimatology in a paper published in 2007.[4] The Center for Sun-Climate Research at the Danish National Space Institute "investigates the connection between solar activity and climatic changes on Earth".[5][6] Its homepage lists several publications earlier works related to cosmoclimatology.[7][8]
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":
A documentary film on Svensmark's theory, The Cloud Mystery, was produced by Lars Oxfeldt Mortensen[10][11] and premiered in January 2008 on Danish TV 2.
Preliminary experimental verification has 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.
Svensmark conducted proof of concept experiments in the SKY Experiment at the Danish National Space Institute.[12]
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.
Scientists are preparing detailed atmospheric physics experiments to test Svensmark's thesis, building on the Danish findings. CERN started a multi-phase project in 2006, including rerunning the Danish experiment. CERN plans to use an accelerator rather than rely on natural cosmic rays. CERN's multinational project will give scientists a permanent facility where they can study the effects of both cosmic rays and charged particles in the Earth's atmosphere.[13] CERN's project is named CLOUD (Cosmics Leaving OUtdoor Droplets).[14] CERN posted a 2009 progress report on the CLOUD project.[15]
On 25 August 2011, the first result of the experiment were published. They show that vapor traces, assumed until now to account for aerosol formation in the lower atmosphere can explain only a tiny fraction of the observed atmospheric aerosol production. The results also show that ionization from cosmic rays significantly enhances aerosol formation. [16]
An early (2003) critique of Svensmark's theory reanalyzed Svensmark's data and suggested that it does not support a correlation between cosmic rays and global temperature changes; it also disputes some of the theoretical bases for the theory.[17] Svensmark replied to the paper, stating that "...nowhere in Peter Laut’s (PL) paper has he been able to explain, where physical data have been handled incorrectly, how the character of my papers are misleading, or where my work does not live up to scientific standards" [18]
Mike Lockwood of the UK's Rutherford Appleton Laboratory and Claus Froehlich of the World Radiation Center in Switzerland published a paper in 2007 which concluded that the increase in mean global temperature observed since 1985 correlates so poorly with solar variability that no type of causal mechanism may be ascribed to it, although they accept that there is "considerable evidence" for solar influence on Earth's pre-industrial climate and to some degree also for climate changes in the first half of the 20th century.[19]
Svensmark's coauthor Calder responded to the study in an interview with LondonBookReview.com, where he put forth the counterclaim that global temperature has not risen since 1999.[20]
Later in 2007, Svensmark and Friis-Christensen brought out a Reply to Lockwood and Fröhlich which concludes that surface air temperature records used by Lockwood and Fröhlich apparently are a poor guide to Sun-driven physical processes, but tropospheric air temperature records do show an impressive negative correlation between cosmic-ray flux and air temperatures up to 2006 if a warming trend, oceanic oscillations and volcanism are removed from the temperature data. They also point out that Lockwood and Fröhlich present their data by using running means of around 10 years, which creates the illusion of a continued temperature rise, whereas all unsmoothed data point to a flattening of the temperature, coincident with the present maxing out of the magnetic activity of the Sun, and which the continued rapid increase in CO2 concentrations seemingly has been unable to overrule.
In April 2008, Professor Terry Sloan of Lancaster University published a paper in the journal Environmental Research Letters titled "Testing the proposed causal link between cosmic rays and cloud cover",[21] which found no significant link between cloud cover and cosmic ray intensity in the last 20 years. Svensmark responded by saying "Terry Sloan has simply failed to understand how cosmic rays work on clouds".[22] Dr. Giles Harrison of Reading University, describes the work as important "as it provides an upper limit on the cosmic ray-cloud effect in global satellite cloud data". Harrison studied the effect of cosmic rays in the UK.[23] He states: "Although the statistically significant non-linear cosmic ray effect is small, it will have a considerably larger aggregate effect on longer timescale (e.g. century) climate variations when day-to-day variability averages out". Brian H. Brown (2008) of Sheffield University further found a statistically significant (p<0.05) short term 3% association between Galactic Cosmic Rays (GCR) and low level clouds over 22 years with a 15 hour delay. Long-term changes in cloud cover (> 3 months)and GCR gave correlations of p=0.06.[24]