Nir Shaviv

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Nir Shaviv is an Associate Professor at the Racah Institute of Physics at the Hebrew University of Jerusalem.

Climate Change Skeptic

Shaviv is a climate change skeptic and was a speaker at the International Conference on Climate Change (2009) hosted by the conservative think tank, the Heartland Institute. While he does believe the earth is warming, he contends that the sun's rays, rather than human produced CO2, are the cause. [1] But a 2009 analysis of data "on the sun's output in the last 25 years of the 20th century has firmly put the notion to rest.The data shows that even though the sun's activity has been decreasing since 1985, global temperatures have continued to rise at an accelerating rate." [2]

Shaviv's arguments and research conclusions have been undermined by subsequent research[3] and his analyses critiqued as "based on unreliable and poorly replicated estimates, selective adjustments of the data (shifting the data, in one case by 40 million years) and [drawing] untenable conclusions, particularly with regard to the influence of anthropogenic greenhouse gas concentrations on recent warming."[4]. Shaviv argues that cosmic rays influence cloud cover, but this link is still under question.[5]

Ties, real and spurious

CFACT

Although a document (the "Provisional list of participants" [1] for the June 2010 U.N. climate talks in Bonn) lists Shaviv as a Senior Advisor with Committee for a Constructive Tomorrow (CFACT), when asked about this connection Shaviv responded "This is the first time I hear of this group"[6] - and in the final list of participants[2], the CFACT contingent was much smaller and did not include Shaviv.

It is not known how Shaviv came to be on the CFACT list.

Articles and resources

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References

  1. "Carbon Dioxide or Solar Forcing?" Science Bits Online, accessed April 2009.
  2. "Solar Activity Cleared of Global Warming Blame" The Age Online, accessed April 2009.
  3. Things Break (pseudonym) (2009-10-22). Nope, cosmic rays still not driving global warming, continued -. The Way Things Break. Retrieved on 2010-12-04. “one of the proposed mechanisms of the alleged cosmic ray-climate connection, championed by Shaviv and Svensmark among others, is the supposed connection between the solar system’s path through our galaxy’s spiral arms and past climate changes. Overholt et al. examine the evidence in a paper entitled Testing the link between terrestrial climate change and galactic spiral arm transit and... find it wanting ...”
  4. Michael Mann and Gavin Schmidt (2005-01-20). Peer Review: A Necessary But Not Sufficient Condition. RealClimate. Retrieved on 2010-12-04. “Shaviv and Veizer (2003) published a paper in the journal GSA Today, where the authors claimed to establish a correlation between cosmic ray flux (CRF) and temperature evolution over hundreds of millions of years, concluding that climate sensitivity to carbon dioxide was much smaller than currently accepted. The paper was accompanied by a press release entitled 'Global Warming not a Man-made Phenomenon', in which Shaviv was quoted as stating,'The operative significance of our research is that a significant reduction of the release of greenhouse gases will not significantly lower the global temperature, since only about a third of the warming over the past century should be attributed to man'. However, in the paper the authors actually stated that 'our conclusion about the dominance of the CRF [cosmic ray flux] over climate variability is valid only on multimillion-year time scales'. Unsurprisingly, there was a public relations offensive using the seriously flawed conclusions expressed in the press release to once again try to cast doubt on the scientific consensus that humans are influencing climate. These claims were subsequently disputed in an article in Eos (Rahmstorf et al, 2004) by an international team of scientists and geologists (including some of us here at RealClimate), who suggested that Shaviv and Veizer’s analyses were based on unreliable and poorly replicated estimates, selective adjustments of the data (shifting the data, in one case by 40 million years) and drew untenable conclusions, particularly with regard to the influence of anthropogenic greenhouse gas concentrations on recent warming (see for example the exchange between the two sets of authors).”
  5. John Cook (2007-09-03). Klaus-Martin Schulte and scientific consensus. SkepticalScience.com. Retrieved on 2010-12-04. “Shaviv 2005 claims cosmic rays are causing global warming. While the link between cosmic rays and clouds are still under question, the more serious problem is that the correlation between cosmic rays and temperature ended in the 1970's when the modern global warming trend began. More on cosmic rays...”
  6. Shaviv 2010, pers. comm.; he also said "if you're looking for dark secrets about my funding...you'll find none"

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External resources

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