Comments 1 to 16:

1. GFW at 13:00 PM on 1 February, 2010
   The section on independent tests is really good showing multiple measurements and proxies for TSI, with solid agreement. Are you aware of any measurements over the 1990-92 period using radio wavelengths (eg 10.7cm) that would also serve as a calibration? BTW, you wrote Challenge instead of Challenger.
   Response: Fixed the Challenger typo, thanks for the tip.
2. batvette at 10:37 AM on 24 February, 2010
   No reason to overthink this: http://science.nasa.gov/.../maunderminimum.jpg It's not rocket science (or big $$$$ research obscuring its findings with acronymic codes to confuse common sense) to see that the latter half of the 20th century was a period of increased solar activity unmatched since recording of which began. The peaks may have decreased somewhat in the last 20 years BUT were still far above the average of the 400 year period- making the expectation that this 20 year period should be observing a cooling effect from solar influence patently absurd. To be exact: "Various independent measurements of solar activity all confirm the sun has shown a slight cooling trend since 1978" Is misleading. It is bad science to be sure. While one could say that solar activity has decreased since 1978 it is completely erroneous to assume that it has decreased in comparison to the 400 years of recorded observation- let alone believe that since 1978 we could calculate that a cooling effect on earth climate should be the result.
3. Riccardo at 10:51 AM on 24 February, 2010
   batvette, as i'm sure anyone will admit, temperature has gone up from the lows during the Maunder Minimum. This post is on the recent trend, where you have slight decrease in solar output but rising temperatures. More on the Maunder Minimum in this recent post
4. Tom Dayton at 11:20 AM on 24 February, 2010
   batvette, in addition to what Riccardo replied, you should read Climate time lag.
5. batvette at 09:28 AM on 26 February, 2010
   Climate lag is precisely the reason I would argue it is fallacious logic to assume there should be a pronounced cooling trend anytime soon after the peak around 1950. Indeed, your own link cites 25 to 50 years. Since the peak was nearly right at 1950 and it was of unprecedented in amplitude over the 400 year period since accurate count began, it should be prudent calculate the residual effect, or lag, should have a duration of 50 years per your own reference, not 30. Even if one accepts a 30 year lag the 4 cycles following it still saw the second, third and fifth most active cycles in the 400 years so should be expected to have continued the warming trend- not cooling. It is furter notable that if you look carefully at that chart you see the bottom swings of each cycle actually became more active than they had been around the 1950 peak, so observations would be skewed as well because the (low) cooling years which countered the unpredented high would not have been as much as had been seen before. To expect any significant cooling after 1980 you'd have to show a cycle or even two which had significantly lower activity than the 400 year average, not merely compare it to an unprecedented high that just occurred and whose residual effects would affect the assumed cooling cycle.
   Response: Note that climate lag doesn't mean there is a delayed response to a change in forcing. Climate responds immediately to forcings. The climate lag refers to the time it takes for the climate to reach equilibrium.
   
   If the sun cooled, the effect on climate would be immediate, a drop in temperature - but it would take years to decades for the climate to eventually reach equilibrium at a stable lower temperature.
   
   We are not observing this. There is no negative energy imbalance gradually reducing to equilibrium. Instead, we're observing a positive energy imbalance that is gradually increasing over time. We're moving further and further away from equilibrium. The increasing CO2 forcing is causing an increasing positive energy imbalance.
6. Tom Dayton at 10:17 AM on 26 February, 2010
   batvette, the severities of the up parts of the cycles are irrelevant, because the down parts of the cycles cancel them. More precisely, the degree to which the up and down parts of the cycles do *not* cancel each other is reflected in irradiance statistics that filter by 11 years by one or another method. Those filtered statistics are the ones that show either flat or slightly down trend since 1950.
7. cjshaker at 19:42 PM on 23 October, 2011
   A believer in CO2 was telling me that the sun's output is now 30% higher than it was when life evolved on the earth. Is that true? Thank you, Chris Shaker
8. Dikran Marsupial at 20:45 PM on 23 October, 2011
   cjshaker Yes, that is essentially correct, the sun was about 30% dimmer when the Earth first formed 4.6 billion years ago. This is well known. However that process of stellar evolution is so slow it has no effect on the climate on timescales of thousands of years. The only real relevance of this to the AGW is that it explains how a snowball Earth could ocurr with high levels of atmospheric CO2, but that is a subject for a different thread. Note the climate has been much warmer in the past, even with the dimmer Sun, the most feasible explanation is the higher levels of greenhouse gasses in the atmosphere at the time. This is knwn as the Faint Young Sun Paradox. I note that you have been very active today posting a large number of papers for discussion on a wide range of topics. Some constructive criticism: this gives the impression that you are not really interested in the answers, because very few people would be able to hold a worthwhile discussion on so many topics simultaneously. I would advise in future that you stick to a small number of topics at any one time so that you can have an in-depth discussion that science demands.
9. Camburn at 06:16 AM on 13 February, 2012
   A good research link to the sun: Dr. Leif Svalgarrd's Research page His current research shows that the TSI has been constant for well over 100 years. Lot's to digest on the link above.
10. Emilio at 10:38 AM on 21 February, 2012
    The maximum of solar cycle 24 is proving to be a fiasco. The cycle 25 can't even occur. http://solarscience.msfc.nasa.gov/predict.shtml http://www.skyandtelescope.com/news/123844859.html
11. scaddenp at 10:56 AM on 21 February, 2012
    That would be undeserved but welcome break for mankind. Let's hope we can make the most of it before the sun returns to normal activity.
12. Riccardo at 11:42 AM on 21 February, 2012
    True, even a few tenth of a degree would buy us some time. Undeserved but welcome.
13. cstanyon69 at 20:30 PM on 23 September, 2013

    Got a question: have you heard of this one:
    
    LINK
    
    I'm sure it's rubbish; the premise is that Judith Lean, the lone solar physicist on the IPCC, had complete control over solar radiation readings. From what you've written above, this seems like tripe, but I'm not so familiar with the field to be sure.
    
    Your comment?

    Response:

    [RH] Hot linked URL that was breaking page formatting

14. Tom Curtis at 00:12 AM on 24 September, 2013

    cstanyon69 @13, the chapter in question has just one out of 45 sections dealing with solar forcing.  That section reads as follows:

    "2.7.1 Solar Variability
    The estimates of long-term solar irradiance changes used in the TAR (e.g., Hoyt and Schatten, 1993; Lean et al., 1995) have been revised downwards, based on new studies indicating that bright solar faculae likely contributed a smaller irradiance increase since the Maunder Minimum than was originally suggested by the range of brightness in Sun-like stars (Hall and Lockwood, 2004; M. Wang et al., 2005). However, empirical results since the TAR have strengthened the evidence for solar forcing of climate change by identifying detectable tropospheric changes associated with solar variability, including during the solar cycle (Section 9.2; van Loon and Shea, 2000; Douglass and Clader, 2002; Gleisner and Thejll, 2003; Haigh, 2003; Stott et al., 2003; White et al., 2003; Coughlin and Tung, 2004; Labitzke, 2004; Crooks and Gray, 2005). The most likely mechanism is considered to be some combination of direct forcing by changes in total solar irradiance, and indirect effects of ultraviolet (UV) radiation on the stratosphere. Least certain, and under ongoing debate as discussed in the TAR, are indirect effects induced by galactic cosmic rays (e.g., Marsh and Svensmark, 2000a,b; Kristjánsson et al., 2002; Sun and Bradley, 2002)."

    Your linked blog post claims that Judith Lean was the only solar physicist among the lead authors of the chapter.  That may well be true.  There were in fact 15 Coordinating Lead authors or lead authors to the chapter.  If membership in that group was coordinated based on relevant expertise by section, we would expect just 1 in 45 (or 1/3 rd of a lead author) to be solar physicists.  Given the nature of the topics discussed, that means solar physicists are over represented among lead authors.

    Of course, the blog is carefull to not point out that lead authors are not the only authors.  In fact, in addition to the 15 Coordinating Lead Authors and lead authors, there are 37 Contributing Authors.  Given an assumption of proportionality, we would therefore expect approximately 2/3rds of a Contributing Author to be a Solar Physicist.  In fact, there is at least one in the form of S. K. Solanki (and may be others that I do not recognize).  Apparently the existence of at least one other solar physicist was not considered worthy of mention by the author of the blog.

    The author of the blog also claims the section was based primarilly on just one paper, of which Lean was a co-author.  In fact 16 papers are cited, of which only two have Lean as co-authors (Lean et al, 1995; Wang et al, 2005).  For both of these, they are cited in conjunction with another paper of which Lean was not an author to make the point being made - and the first of these is cited because it was previously cited in Assessement Report 3.  None of Solanki's papers are cited in that section.

    It should be noted that 7 other papers with Lean as a coauthor, and two with Solanki as a coauthor are also included in refferences, but if cited, are cited in other sections of the chapter.

    Not content with misrepresenting or concealing the basic facts of the case, the paper also attempts to claim the sun is responsible for recent warming by trotting out the original graph from Friis-Christensen (1991), which has been resoundlingly rebutted by later work, as explained here.  It also includes some slanderous personal communications that attempt to rebut the PMOD composite by ad hominen, but I'll not adress those.

15. chanut.th at 22:32 PM on 26 March, 2018

    The sun's heat is increased, but it is not the main factor for the increase in temperature. Even though the sun is burning, burning and spreading the sun, and the sun is expanding, it is hotter.

    The world is being heated by the increase in greenhouse gases caused by the burning of fossil fuels and transportation or transportation. Why global warming does not depend on the green house effect.In spite of this, greenhouse gases have increased and global warming is due to the destruction of the ozone layer.

16. DPiepgrass at 10:12 AM on 3 April, 2018

    Chanut, the ozone hole does not cause global warming. Why did you say that?

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