Nir Shaviv

Shaviv started taking courses at the Israel Institute of Technology in Haifa at age 13.{{Cite web | title = Article from Ma'ariv LaNoar |language=he | url=http://www.phys.huji.ac.il/~shaviv/misc/Maariv-LaNoar-1987.jpg }} After a 3-year service in the IDF Unit 8200, he received in 1994 a Master of Science in physics and a doctorate during 1994–96. During 1996–99, he was a Lee DuBridge Prize Fellow at Caltech's TAPIR (Theoretical Astrophysics) group. During 1999–2001, he was in a postdoctorate position at the Canadian Institute for Theoretical Astrophysics. In 2001–2006, he was a senior lecturer at Racah Institute of physics at the Hebrew University of Jerusalem. In 2006–2012, he was an associate professor, and full professor since 2012. Between 2008 and 2011, he was the head of the faculty union of the Hebrew University, and he served as the chairman of coordinating council of faculty unions between 2010 and 2014. In 2014, he became a member of the Institute for Advanced Study in Princeton, and served as the chairman of The Racah Institute of Physics between 2015 and 2019.

In 1999, Shaviv has shown that inhomogeneities in stellar atmospheres reduce the effective opacity and thus increase the Eddington luminosity.{{cite journal|last1=Shaviv|first1=Nir J.|title=The Eddington Luminosity Limit for Multiphased Media|journal=The Astrophysical Journal|volume=494|issue=2|year=1998|pages=L193–L197|issn=0004-637X|doi=10.1086/311182|bibcode=1998ApJ...494L.193S|citeseerx=10.1.1.47.5114|s2cid=17579448 }} Shaviv later showed that atmospheres are inherently unstable as the Eddington luminosity is approached,{{cite journal|last1=Shaviv|first1=Nir J.|title=The Nature of the Radiative Hydrodynamic Instabilities in Radiatively Supported Thomson Atmospheres|journal=The Astrophysical Journal|volume=549|issue=2|year=2001|pages=1093–1110|issn=0004-637X|doi=10.1086/319428|bibcode=2001ApJ...549.1093S|arxiv=astro-ph/0010425|s2cid=17917305}} that these atmospheres will develop continuum driven winds that explain the appearance of eta-Carinae and classical nova eruptions.

In 2010, Shaviv made the prediction that Type IIn supernova should have super-Eddington outbursts before the main supernova explosions since the super-Eddington states can naturally explain the circum-stellar material present around the supernova at the time of explosion (Giving the narrow lines observed in the spectrum, i.e., the “n” in the Type IIn).{{Cite web | title = Supernova Precursor | url=http://www.sciencebits.com/SN2010mc }} Such precursors were later detected with the Palomar Transient Factory, making them the first systematically detected supernova precursors.{{cite journal|last1=Ofek|first1=E. O.|last2=Sullivan|first2=M.|last3=Cenko|first3=S. B.|last4=Kasliwal|first4=M. M.|last5=Gal-Yam|first5=A.|last6=Kulkarni|first6=S. R.|last7=Arcavi|first7=I.|last8=Bildsten|first8=L.|last9=Bloom|first9=J. S.|last10=Horesh|first10=A.|last11=Howell|first11=D. A.|last12=Filippenko|first12=A. V.|last13=Laher|first13=R.|last14=Murray|first14=D.|last15=Nakar|first15=E.|last16=Nugent|first16=P. E.|last17=Silverman|first17=J. M.|last18=Shaviv|first18=N. J.|last19=Surace|first19=J.|last20=Yaron|first20=O.|title=An outburst from a massive star 40 days before a supernova explosion|journal=Nature|volume=494|issue=7435|year=2013|pages=65–67|issn=0028-0836|doi=10.1038/nature11877|pmid=23389540|arxiv=1302.2633|bibcode=2013Natur.494...65O|s2cid=23437495}}

Shaviv has been one of the proponents of a cosmic ray climate link. In 2003 he has shown that the cosmic ray flux over the past billion years can be reconstructed from the exposure ages of Iron meteorites, that these flux variations are expected from spiral arm passages, and they correlate with the appearance of ice age epochs on Earth.{{cite journal|last1=Shaviv|first1=Nir J.|title=The spiral structure of the Milky Way, cosmic rays, and ice age epochs on Earth|journal=New Astronomy|volume=8|issue=1|year=2003|pages=39–77|issn=1384-1076|doi=10.1016/S1384-1076(02)00193-8|bibcode=2003NewA....8...39S|arxiv=astro-ph/0209252|s2cid=879406}} In a later work with Ján Veizer, it was demonstrated that the temperature reconstruction over the Phanerozoic correlates with the cosmic ray flux, but it does not correlate with the {{CO2}} reconstruction, thus placing an upper limit on the effects of {{CO2}}. This prompted several reactions by the climate community and rebuttals by Shaviv and his colleagues.{{Cite web | title = Climate Debate | url=http://www.sciencebits.com/Climate_Debate }}

He has also shown{{cite journal|last1=Shaviv|first1=Nir J.|title=Toward a solution to the early faint Sun paradox: A lower cosmic ray flux from a stronger solar wind|journal=Journal of Geophysical Research|volume=108|issue=A12|pages=1437|year=2003|issn=0148-0227|doi=10.1029/2003JA009997|bibcode=2003JGRA..108.1437S|arxiv=astro-ph/0306477|s2cid=11148141}} that the cosmic ray climate link explains part the faint young Sun paradox, since the slowly decreasing solar wind will give rise to a cooling effect that compensates the solar irradiance increase. Moreover, long term star formation activity in the Milky Way correlate with long term climate variations.

In a more recent work with Andreas Prokoph and Ján Veizer,{{cite journal|last1=Shaviv|first1=Nir J.|last2=Prokoph|first2=Andreas|last3=Veizer|first3=Ján|title=Is the Solar System's Galactic Motion Imprinted in the Phanerozoic Climate?|journal=Scientific Reports|volume=4|year=2014|pages=6150|issn=2045-2322|doi=10.1038/srep06150|pmid=25141775|pmc=4139944|bibcode=2014NatSR...4E6150S}} it was argued that the reconstructed temperature has a clear 32 million year oscillation that is consistent with the Solar System's motion perpendicular to the galactic plane. The oscillation also appears to have a secondary modulation consistent with the radial epicyclic motion of the Solar System.

Because the existence of a significant cosmic ray climate link implies that solar variability will also have a large effect on the climate, Shaviv advocated the idea that natural climate variations play a significant role in 20th century climate change. Moreover, if solar activity increase over the 20th century contributed to warming in addition to the anthropogenic forcing, then the overall climate sensitivity should be lower than advocated by standard scenarios which do not include solar forcing.{{Cite web | title = Nothing New Under the Sun | url=http://www.sciencebits.com/NothingNewUnderTheSun }}

In 2008, Shaviv used the oceans as a giant calorimeter to quantify the solar radiative forcing. He found that the peak to peak variations are close to 1 W/m², significantly more than can be expected from the changes in the solar irradiance.{{cite journal|last1=Shaviv|first1=Nir J.|title=Using the oceans as a calorimeter to quantify the solar radiative forcing|journal=Journal of Geophysical Research|volume=113|issue=A11|year=2008|pages=n/a|issn=0148-0227|doi=10.1029/2007JA012989|bibcode=2008JGRA..11311101S|citeseerx=10.1.1.173.2162}} In 2011, he published a paper with Shlomi Ziskin arguing that the solar variability explains about half the 20th century warming, with the other half attributable to anthropogenic forcing.{{cite journal|last1=Ziskin|first1=Shlomi|last2=Shaviv|first2=Nir J.|title=Quantifying the role of solar radiative forcing over the 20th century|journal=Advances in Space Research|volume=50|issue=6|year=2012|pages=762–776|issn=0273-1177|doi=10.1016/j.asr.2011.10.009|bibcode=2012AdSpR..50..762Z}}{{primary source inline|date=February 2016}}

Shaviv's solar hypothesis has been disputed by Mike Lockwood and Claus Froehlich (1936–2019){{cite web|title=In Memoriam: Claus Fröhlich|website=Swiss Physical Society (sps.ch)|year=2019|url=https://sps.ch/en/articles/obituaries/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.{{Cite news | date=2007-07-11 | url=http://www.theage.com.au/news/national/solar-activity-cleared-of-global-warming-blame/2007/07/11/1183833599508.html | title = Solar activity cleared of global warming blame | newspaper = The Age | place = Australia}} Shaviv argues that Lockwood and Froehlich's analysis is flawed for a number of reasons.{{Cite web |title=Nir Shaviv: Why is Lockwood and Fröhlich meaningless?|date=22 July 2007|url=http://motls.blogspot.com/2007/07/nir-shaviv-why-is-lockwood-and-frohlich.html|type=blog}} 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. Later quantitative modeling showed that indeed there is no discrepancy. The perceived "hiatus" in the early 2000s is a natural consequence of the decreased solar activity.

Shaviv disagrees with the scientific consensus on human-caused climate change.[https://www.desmogblog.com/nir-shaviv Nir Shaviv] Desmogblog. Retrieved 12/07/2018. He claims that solar activity changes have contributed between half to two thirds of the warming over the 20th century,{{Cite web|url=http://www.sciencebits.com/CO2orSolarHYPERLINK|title=Carbon Dioxide or Solar Forcing? {{!}} ScienceBits|website=www.sciencebits.com|language=en|access-date=2019-02-14}} and that climate sensitivity should be on the low side ΔT_x2=1.3±0.4 °C compared with IPCC's range of ΔT_x2=1.5 to 4.5 °C per {{CO2}} doubling.{{Cite web|url=http://www.sciencebits.com/OnClimateSensitivity|title=On Climate Sensitivity and why it is probably small {{!}} ScienceBits|website=www.sciencebits.com|access-date=2019-02-14}}

Shaviv was interviewed for The Great Global Warming Swindle documentary. In the film he states:

{{cquote|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.{{Citation| title = The Great Global Warming Swindle | medium = Documentary | postscript = ; Martin Durkin (director)| publisher = WAGtv for Channel 4 | location=United Kingdom | time = 2min23–2min31 | date = March 8, 2007 | title-link = The Great Global Warming Swindle }}}}

In 2012, he contributed, along with Werner Weber, Henrik Svensmark and Nicola Scafetta, to the book Die kalte Sonne. Warum die Klimakatastrophe nicht stattfindet (The Cold Sun) of Fritz Vahrenholt and Sebastian Lüning,{{cite web|title=Dr. Sebastian Lüning, Executive Director (with Dr. Heiner Marx & Dr. Markus Pfänder)|website=The K-UTEC AG Salt Technologies Management|url=https://www.k-utec.de/en/company/management}} a book expressing climate change denial, which attracted considerable interest in Germany.Fritz Vahrenholt, Sebastian Lüning: Die kalte Sonne. Warum die Klimakatastrophe nicht stattfindet. Hoffmann und Campe, Hamburg 2012, {{ISBN|3-455-50250-4}}. Numerous scientists criticised the book and considered its underlying assumptions to be either outdated or highly speculative.{{cite news | url=http://www.zeit.de/wissen/umwelt/2012-08/klimaforscher-vahrenholt-kritik | title=Klimawandel-Debatte: Forscher fühlen sich von Klimaskeptiker Vahrenholt instrumentalisiert |trans-title=Researchers feel instrumentalised by climate sceptic Vahrenholt |author=Toralf Staud| newspaper=Die Zeit | publisher=zeit.de |date=August 10, 2012 |access-date=2020-10-10}}{{cite web | url=https://www.focus.de/wissen/weltraum/odenwalds_universum/tid-24984/umstrittene-buchveroeffentlichung-die-kalte-sonne-halbwahrheiten-ueber-die-co2-luege_aid_712273.html | title=Umstrittenes Buch "Die kalte Sonne": Halbwahrheiten über die CO₂-Lüge |trans-title=Controversial book "The Cold Sun": Half-truths about the CO₂ lie |author=Michael Odenwald |publisher=Focus Online |date=July 30, 2012 |access-date=2020-10-10}}{{cite news | url=http://www.zeit.de/2012/07/Klimawandel-Fakten/komplettansicht | title=Erderwärmung: Skeptiker im Faktencheck |author=Toralf Staud | newspaper=Die Zeit |publisher=zeit.de |date=February 9, 2012 |access-date=2020-10-10}}{{cite web|url=http://www.spektrum.de/rezension/die-kalte-sonne/1145939 |title=Rezension Die kalte Sonne, Fritz Vahrenholt, Sebastian Lüning |author=Sven Titz |publisher=spektrum.de |date=15 August 2015 |access-date=April 15, 2016}}

In 2018, the German Bundestag's environment committee invited him as an expert to the German Parliament. There he denied that carbon dioxide had a substantial effect on climate change[https://www1.wdr.de/daserste/monitor/sendungen/klimaskeptiker-100.html Klimawandel durch kosmische Strahlung? Klimawandel-Leugner im parlamentarischen Alltag] ARD Monitor. Retrieved 12/07/2018 and claimed the Intergovernmental Panel on Climate Change (IPCC) was ignoring information that the sun was the primary cause for climate change.[https://www.bundestag.de/dokumente/textarchiv/2018/kw48-pa-umwelt-klima/578906 Große Hoffnungen und geringe Erwartungen an die UN-Klimakonferenz] German Bundestag. Retrieved 12/07/2018.

Nir Shaviv has been a speaker for the Heartland Institute.{{Cite web|url=https://www.heartland.org/about-us/who-we-are/nir-shaviv|title=Who We Are - Nir Shaviv {{!}} Heartland Institute|website=www.heartland.org|access-date=2019-08-10}}{{Cite web|url=https://www.heartland.org/multimedia/videos/nir-shaviv-iccc13-panel-1-scientific-observations|title=Videos - Nir Shaviv, ICCC13 (Panel 1: Scientific Observations) {{!}} Heartland Institute|website=www.heartland.org|access-date=2019-08-10|archive-date=2019-08-10|archive-url=https://web.archive.org/web/20190810125216/https://www.heartland.org/multimedia/videos/nir-shaviv-iccc13-panel-1-scientific-observations|url-status=dead}}

• 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
• 2014 IBM Einstein Fellowship, Institute for Advanced Study, Princeton

• {{Citation |last1=Elphick |first1=C |last2=Regev |first2=O. |last3=Shaviv |first3=Nir J |name-list-style=amp |year=1992 | title = Dynamics of Fronts in Thermally Bistable Fluids |journal=The Astrophysical Journal |volume=392 |issue=1 |pages=106 |doi = 10.1086/171410 |bibcode=1992ApJ...392..106E|doi-access=free }}
• {{Citation |last=Shaviv |first=Nir J |year=1998 |title=Can Nonlinear Structure Form at the Era of Decoupling? |journal=Mon. Not. R. Astron. Soc. |volume=297 |issue= 4|pages=1245–1260 |doi=10.1046/j.1365-8711.1998.01602.x|doi-access=free |arxiv = astro-ph/9804292 |bibcode = 1998MNRAS.297.1245S |s2cid=126440 }}
• {{Citation |last1=Dar |first1=A |last2=Laor |first2=A. |last3=Shaviv |first3=Nir J |name-list-style=amp |year=1998 |title= Life extinctions by cosmic ray jets |journal=Physical Review Letters |volume=80 |issue=26 |pages=5813–5816 |doi = 10.1103/PhysRevLett.80.5813 |bibcode=1998PhRvL..80.5813D|arxiv = astro-ph/9705008 |s2cid=14143132 }}
• {{Citation |last=Shaviv |first=Nir J |year=2000 |title=The Porous Atmosphere of eta-Carinae |journal=The Astrophysical Journal Letters |volume=532 |issue= 2|pages=L137–L140 |doi=10.1086/312585 |pmid=10715243 |bibcode=2000ApJ...532L.137S|arxiv = astro-ph/0002212 |s2cid=705762 }}
• {{Citation |last=Shaviv |first=Nir J |year=2003 |title=The Spiral Structure of the Milky Way, Cosmic-Rays and Ice-Age Epochs on Earth |journal=New Astronomy |volume=8 |issue=1 |pages=39–77 |doi=10.1016/S1384-1076(02)00193-8 | author-mask = 8 |arxiv = astro-ph/0209252 |bibcode = 2003NewA....8...39S |s2cid=879406 }}
• {{Citation | first1=Nir J | last1=Shaviv |first2=Ján |last2=Veizer |author2-link=Jan Veizer |title=Celestial driver of Phanerozoic climate? |volume=13 |issue=7 |year=2003 |pages=4–10 |journal=GSA Today |doi= 10.1130/1052-5173(2003)013<0004:CDOPC>2.0.CO;2 |author-mask = 8 |doi-access=free | bibcode=2003GSAT...13g...4S }}
• {{Citation |last= Shaviv |first= Nir J |year=2005 |title=On Climate Response to Changes in the Cosmic Ray Flux and Radiative Budget | journal=J. Geophys. Res. Space Phys. |volume=110 |issue=A8 |pages=A08105 |doi=10.1029/2004JA010866 |bibcode = 2005JGRA..110.8105S |author-mask = 8 |arxiv = physics/0409123 |s2cid= 16364672 }}
• {{Citation |last1=Scherer |first1=K |last2=Fichtner |first2=H |last3=Borrmann |first3=T |last4=Beer |first4=J |last5=Desorgher | first5 = L |last6=Flükiger |first6=E |last7=Fahr |first7=H |last8=Ferreira |first8=SE |last9=Langner |first9= UW |last10=Potgieter |first10=M. S. |last11=Heber |first11=B. |last12=Masarik |first12=J. |last13=Shaviv |first13=N. |last14=Veizer |first14=J. |name-list-style=amp |year=2006 |title= Interstellar-Terrestrial Relations: Variable Cosmic Environments, The Dynamic Heliosphere, and Their Imprints on Terrestrial Archives and Climate |journal=Space Science Reviews |volume=127 |issue=1–4 |pages=327 |doi = 10.1007/s11214-006-9126-6 |bibcode=2006SSRv..127..327S|s2cid=119640116 |url=https://boris.unibe.ch/20756/ |display-authors=8 }}

• {{Citation | first = Nir J | last = Shaviv | contribution = Climate Change and the Cosmic Ray Connection | title = International Seminar on Nuclear War and Planetary Emergencies – 30th session | place = Erice, Italy | date = August 2003 | publisher = Ed. R. Ragaini, World Scientific }} (invited)

{{Reflist}}

• [http://sciencebits.com/ Sciencebits.com], Shaviv's weblog
• Shaviv's [http://www.phys.huji.ac.il/~shaviv home page] at the Hebrew University

{{Authority control}}

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Category:Living people

Category:Israeli scientists

Category:1972 births

Category:American climatologists

Category:Scientists from Ithaca, New York

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Category:Unit 8200 alumni