Tuesday, January 22, 2013

Paper finds tiny changes in solar activity explain N Hemisphere temps over past millennium

Climate alarmists often claim that tiny changes in solar activity cannot explain the temperature changes of the past millennium. However, a paper published in Geophysical Research Letters finds tiny changes in solar activity of .07% or less can account for changes in Northern Hemisphere [NH] temperature over the past 1,000 years. The paper examines 4 reconstructions of solar activity, each of which show a 'hockey stick' of solar activity in the 20th century. The paper adds to hundreds of other peer-reviewed publications demonstrating that tiny changes in solar activity can account for climate and temperature changes on Earth. 


 
Added arrow shows the ensemble reconstructed temperature at the end of the record in the year 2000. All 4 solar reconstructions indicate solar activity was at the highest levels of the past millennium at the end of the record.
Are the most recent estimates for Maunder Minimum solar irradiance in agreement with temperature reconstructions?
Georg Feulner

Estimates for the total solar irradiance (TSI) during the 17th-century Maunder Minimum published in the last few years have pointed towards a TSI difference of 0.2–0.7 W m−2 as compared to the 2008/2009 solar minimum. Two recent studies, however, give anomalies which differ from this emerging consensus. The first study indicates an even smaller TSI difference, placing the Maunder Minimum TSI on the same level as the 2008/2009 minimum. The second study on the other hand suggests a very large TSI difference of 5.8 W m−2. Here I use coupled climate simulations to assess the implications of these two estimates on Northern-hemisphere surface air temperatures over the past millennium. Using a solar forcing corresponding to the estimate of the first study, simulated Northern-hemisphere temperatures over the past millennium are consistent with reconstructed surface air temperatures. The large TSI differences between times of high and low solar activity as suggested by the second study, however, yield temperatures during all past grand solar minima that are too low, an excessive variance in Northern-hemisphere temperature on timescales of 50–100 years as compared to reconstructions, and temperatures during the first half of the 20th century which are too low and inconsistent with the instrumental temperature record. In summary this suggests a more moderate TSI difference of less than 1 W m−2 and possibly as low as 0–0.3 W m−2.

4 comments:

  1. Hi MS,

    I think you are misunderstanding this.

    By concluding that simulations using the more moderate TSI 'possibly as low as 0-0.3 W m-2', the author's implication is, presumably, that GHGs explain the large difference in temperature between now and the LIA.

    Also, it says in the article -

    For all RCPs [representative CO2 concentration pathways], a 21st‐century grand solar minimum with a TSI as estimated by Schrijver et al. [2011] leads to global temperatures during 2071–2100 which are by 0.04°C lower as compared to a continuing 11‐year solar activity cycle.

    So the author's conclusion is that the effect of a future grand solar minimim would be negligible.

    I'd be interested to see the study that found a TSI change of 5.8 W m-2.

    ReplyDelete
    Replies
    1. Hi,

      1. The author shows - just rearranging sentences in the abstract - that:

      "In summary this suggests a more moderate TSI difference of less than 1 W m−2 and possibly as low as 0–0.3 W m−2"

      "Using a solar forcing corresponding to the estimate of the [less than 1 W m−2 and possibly as low as 0–0.3 W m−2], simulated Northern-hemisphere temperatures over the past millennium are consistent with reconstructed surface air temperatures."

      For all RCPs [representative CO2 concentration pathways], a 21st‐century grand solar minimum with a TSI as estimated by Schrijver et al. [2011] leads to global temperatures during 2071–2100 which are by 0.04°C lower as compared to a continuing 11‐year solar activity cycle.

      This is the required genuflection to AGW required in all studies if you want your article to be published. It says that if you use the [highly flawed] IPCC models, that GHGs will overwhelm the decrease in solar forcing in the 21st century. For the thousands of reasons pointed out on this site, the IPCC models do not provide skillful projections, and thus, this statement is meaningless.

      Delete
  2. I don't have a comment on this post but I couldn't find this paper in your post so I thought I would draw it to your attention: http://www.arl.noaa.gov/documents/JournalPDFs/ThompsonEtal.Nature2012.pdf

    ReplyDelete

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