Nir Shaviv

Nir Shaviv
Nir Shaviv, 2009
Born	July 6, 1972 (1972-07-06) Ithaca, New York
Nationality	Israeli American
Fields	Astrophysics
Institutions	Hebrew University of Jerusalem
Influences	Jan Veizer Henrik Svensmark

Nir Joseph Shaviv (Hebrew: ניר יוסף שביב‎, born July 6, 1972, in Ithaca, New York) is an Israeli‐American physics professor, carrying out research in the fields of astrophysics and climate science. He is currently an associate professor at the Racah Institute of Physics of the Hebrew University of Jerusalem. He is also the head of the national coordinating council of faculty unions in Israel.

He is most well known for his solar and cosmic rays hypothesis of climate change. In 2002, Shaviv hypothesised that passages through the Milky Way's spiral arms appear to have been the cause behind the major ice-ages over the past billion years. In his later work, co-authored by Jan Veizer, a low upper limit was placed on the climatic effect of CO₂.

His most known contribution to the field of astrophysics was to demonstrate that the Eddington luminosity is not a strict limit, namely, that astrophysical objects can be brighter than the Eddington luminosity without blowing themselves apart. This is achieved through the development of a porous atmosphere that allows the radiation to escape while exerting little force on the gas. The theory was correctly used to explain the mass-loss in Eta Carinae's giant eruption, and the evolution of classical nova eruptions.^{[citation needed]}

Shaviv was one of the global warming skeptics interviewed for The Great Global Warming Swindle documentary. In the film he states:

“

A few years ago if you would ask me I would tell you it's CO2. Why? Because just like everyone else in the public I listened to what the media had to say.

”

Solar variation

Shaviv’s solar hypothesis has been disputed by Mike Lockwood and Claus Froehlich in an analysis of the sun’s output over the last 25 years. They argue that the sun’s activity has been decreasing since 1985 while global temperatures have continued to rise.

Shaviv argues that Lockwood and Froehlich's analysis is flawed for a number of reasons. Firstly, while sunspot activity declined after 1985, cosmic ray flux reached a minimum in 1992 and contributed to warming during the 1990s. Secondly, Shaviv argues that short term variations in radiative forcing are damped by the oceans, leading to a lag between changes in solar output and the effect on global temperatures. While the 2001 maximum was weaker than the 1990 maximum, increasing solar activity during previous decades was still having a warming effect, not unlike the lag between noon and the hottest hour of the day.

Education

Shaviv studied, during 1987–90, physics at the Israel Institute of Technology in Haifa and finished his BA as best in class. During his military service (1990–93) he continued his studies 1992 and coauthored his first papers in astrophysics. In 1994 he received a Master of Science in physics and a doctorate during 1994–96. During 1996–99 he was Lee DuBridge Prize Fellow at Caltechs TAPIR (Theoretical Astrophysics Group). During 1999–2001 he was in a postdoctorate position at the university of Toronto, and 2001–6 was senior lecturer at Racah Institut of physics at University of Jerusalem.

Prizes

• 1996 Wolf foundation award for excellence as PhD student
• 1996 Lee A. DuBridge scholarship at Caltech
• 2000 Beatrice Tremaine scholarship in Toronto
• 2004 Siegfried Samuel Wolf lecture for nuclear physics

Selected papers

• Elphick, C; Regev, O. & Shaviv, Nir J (1992), "Dynamics of Fronts in Thermally Bistable Fluids", The Astrophysical Journal 392 (1): 106, Bibcode 1992ApJ...392..106E, doi:10.1086/171410 
• Shaviv, Nir J (1998), "Can Nonlinear Structure Form at the Era of Decoupling?", Mon. Not. of the Royal Astr. Soc. 297 (4): 1245, doi:10.1046/j.1365-8711.1998.01602.x 
• Dar, A; Laor, A. & Shaviv, Nir J (1998), "Life extinctions by cosmic ray jets", Physical Review Letters 80 (26): 5813–5816, Bibcode 1998PhRvL..80.5813D, doi:10.1103/PhysRevLett.80.5813 
• Shaviv, Nir J (2000), "The Porous Atmosphere of eta-Carinae", The Astrophysical Journal Letters 532 (2): L137, Bibcode 2000ApJ...532L.137S, doi:10.1086/312585 
•          (2003), "The Spiral Structure of the Milky Way, Cosmic-Rays and Ice-Age Epochs on Earth", New Astronomy 8: 39, doi:10.1016/S1384-1076(02)00193-8 
•         ; Veizer, Ján (2003), "Celestial driver of Phanerozoic climate?", GSA Today 13 (7): 4–10, doi:10.1130/1052-5173(2003)013<0004:CDOPC>2.0.CO;2 
•          (2005), "On Climate Response to Changes in the Cosmic Ray Flux and Radiative Budget", J. Geophys. Res.–Space Phys. 110 (A8): A08105, Bibcode 2005JGRA..11008105S, doi:10.1029/2004JA010866 
• Scherer, K; Fichtner, H; Borrmann, T; Beer, J; Desorgher, L; Flükiger, E; Fahr, H; Ferreira, SE et al. (2006), "Interstellar-Terrestrial Relations: Variable Cosmic Environments, The Dynamic Heliosphere, and Their Imprints on Terrestrial Archives and Climate", Space Science Reviews 127 (1–4): 327, Bibcode 2006SSRv..127..327S, doi:10.1007/s11214-006-9126-6 

Lectures (Selection)

• Shaviv, Nir J (August 2003), "Climate Change and the Cosmic Ray Connection", International Seminar on Nuclear War and Planetary Emergencies – 30thsession, Erice, Italy: Ed. R. Ragaini, World Scientific  (invited)

See also

• List of scientists opposing the mainstream scientific assessment of global warming

External links

• Sciencebits.com, Shaviv's weblog
• Shaviv's home page at the Hebrew University