Busting the myth buster 2: It’s the Sun

This is the second post in the series rebutting John Cook’s 10 most used climate myths  at Skeptical Science. Climate myth 2 “Its the Sun”.

Sun and climate moving in opposite directions

“Over the past few hundred years, there has been a steady increase in the numbers of sunspots, at the time when the Earth has been getting warmer. The data suggests solar activity is influencing the global climate causing the world to get warmer.” (BBC)

Cook actually presents a decent and interesting chart that shows total solar irradiance (TSI) declining slowly while temperatures rise. TSI variance is in fact the only and minuscule natural climate forcing considered by the IPCC . Cooks TSI chart is model based since satellite measurements began around 1980. Since then TSI variance has had negligible impact upon climate.

Figure 1: Annual global temperature change (thin light red) with 11 year moving average of temperature (thick dark red). Temperature from NASA GISS. Annual Total Solar Irradiance (thin light blue) with 11 year moving average of TSI (thick dark blue). TSI from 1880 to 1978 from Krivova et al 2007 (data). TSI from 1979 to 2009 from PMOD (see thePMOD index page) Figure and caption from Sceptical Science.

So what’s up? Why is this not a climate myth? The simple explanation lies in the fact that the sceptic argument is normally founded on solar magnetic field strength and not on TSI at all. And so once again Cook misses, misrepresents or misunderstands the sceptic argument completely.

So why should variations in solar magnetic field influence climate on Earth and where is the evidence that it may have done so? It is worth pointing out that there are competing theories. All or none may have a measurable impact. This is NOT settled science. But it could be a very large piece of climate jigsaw, not yet properly understood but with potentially large impacts. At this point I was going to lay out the various lines of evidence for solar influence on Earth’s climate but that has grown into a quite substantial post that will come separately in a day or two.

[Note added 16:20, 18th Feb: Commenter William points out that Skeptical Science has an advanced tab which does go into great detail about a range of solar variables, so I stand corrected. Thank you William. Each variable is successively debunked and dismissed. Above I do say “All or none may have a measurable impact” and so any conclusion here is based on how one judges and weighs evidence. In my next post I will lay out the evidence for solar influence in a rather more balanced way.]

This entry was posted in Climate change, Political commentary and tagged , , , , . Bookmark the permalink.

15 Responses to Busting the myth buster 2: It’s the Sun

  1. A C Osborn says:

    Also to be considered are the changes in
    UV Radiation (10% variation compared to 1% TSI)
    Solar Wind (particles)
    Solar Wind affects on Cosmic Radiation.
    Solar Electric and Magnetic Winds and fields on Earth’s Magnetic Fields and Atmosphere.

    Leif Svalgaard is one of the strongest supporters of “their is not enough Solar variation to affect the Climate”.

  2. Yvan Dutil says:

    All solar activity induces are correlated among each other at ,more than 80%. I personally know people who have done their thesis on the relationship of the sun with climate. Under any circumstance, the impact can only be weak in present time.

  3. William says:

    Euan, really! The “Advanced” page (http://www.skepticalscience.com/solar-activity-sunspots-global-warming-advanced.htm) has heaps of graphs and description and yet you restrict yourself to the “basic” page. There’s even a section on “Solar magnetic field” and a graph showing its correlation with TSI.

  4. Rui N Rosa says:

    Dear Euan: I don’t want to take sides although I have opinions. I just offer a paper I was part of a few years ago: http://home.uevora.pt/~ahr/B.pdf . This is an example to make the point of how complex the aymospheric processes are that lead to the cloud cover on Earth. This is a most relevant point – cloud cover sensitivity regardins atmosheric dynamics and boundary conditions – volcanic activity, geomagnetic field, land cover, cosmic radiation, solar fluxes…. Thanks for your most interesting studies and posts.

    • A C Osborn says:

      That is an interesting paper, i do like works on the electric fields, long neglected my most of modern science.

  5. Doug Brodie says:

    Cook makes no mention of the effective change in solar intensity at the earth’s surface which can result from natural changes in cloud cover. See Clive Best’s article “Do clouds control climate? http://clivebest.com/blog/?p=5694

    He also doesn’t mention changes in UV radiation. From “The Neglected Sun”, by Vahrenholt and Lüning:
    “The IPCC’s main reason for ignoring the sun is its minimal (0.1 per cent) variation in total solar irradiance measured over the course of the 11-year solar cycles. With such a marginal change in irradiance, one simply cannot expect the global temperature to be significantly affected, the IPCC says. However, it overlooks a crucial detail. In the subdomain of UV irradiation, strong fluctuations do indeed occur, of up to 70 per cent. UV light is converted to heat in the ozone layer and ionosphere and , as a result, leads to a formidable temperature roller-coaster with magnitudes of change reaching several degrees Celsius.”

  6. JerryC says:

    “Cooks TSI chart is model based since satellite measurements began around 1980. Since then TSI variance has had negligible impact upon climate.”

    Haha. I downloaded the Excel file that Cook’s chart is based on and it gives you TSI readings down to 6 (!) decimal places all the way back to 1611. All based on 30 years of satellite data. Is there anything these models can’t do?

  7. Retired Dave says:

    Doug Brodie

    You beat me too it – after reading “The Neglected Sun”, by Vahrenholt and Lüning with the wealth of bibliography related to papers on the subject one realises that the IPCC is guilty of -snip-.

    This post at WUWT back when AR5 was first leaked tells it all –


    We can’t think of anything else so it must be CO2 – solar gets hardly a mention in AR5 and is dismissed, despite a huge amount of evidence to the contrary.

    Sorry Euan – I expect that you were going to tell us chapter and verse in your next post.

  8. rogue says:

    Why, on a daily basis, is it warmest around 3PM, when solar radiation is at its peak at noon?.
    Why, in the northern hemisphere, is summer warmest in August when the solstice is in June?

    You have to think about integration of insulation over days and seasons. There is certainly a capacitative effect from ocean (& land) warming, so the phase shift isn’t 90°, but this explains the lag in peak warmth.

  9. roberto says:

    On a related issue:

    “The Sun is the climate pacemaker I. Equatorial Pacific Ocean temperatures”

    D.H. Douglass, R.S. Knox, Physics Letters A (2014)

    … and…

    “The Sun is the climate pacemaker II. Global ocean temperatures”

    D.H. Douglass, R.S. Knox, Physics Letters A (2014)

    … downloadable here:


    An interesting excerpt from the conclusions of the second one:

    “Global ocean temperature time series from the surface to depths of 2000 m since the year 2000 are found to agree in detail with those of other diverse climate indices.
    It is asserted that these systems are driven by a forcing unquestionably of solar origin that has two manifestations: (1) a direct phase-locked response to what is identified as a solar forcing at a frequency of 1.0 cycle/yr for the whole time series; (2) a second phase-locked response at a period of two years or three years.
    With these findings it is becoming clear that the entire climate system is responding to the varying incident solar radiation, and is subject to interactions, most likely nonlinear, that produce the subharmonics of two or three year period, and is moreover evolving non-continuously, as evidenced by breaks in the pattern whose timing can be identified with known climate shifts.
    The most prominent manifestations of the pattern are found in the El Niño/La Niña phenomena.
    As emphasized in [2], the “natural” periodicity of El Niño/La Niña is two or three years, and observations of longer intervals should be considered probable evidence for an intervening climate shift.”


Comments are closed.