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Monday, 8 October, 2007

Svensmark and Friis-Christensen rebut Lockwood's solar paper

Recently, Henrik Svensmark and Eigil Friis-Christensen published Reply to Lockwood and Fröhlich - The persistent role of the Sun in climate forcing, rebutting Mike Lockwood's Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. It's a curious paper, in some parts reading more like a skeptic op-ed than scientific literature. In just a few paragraphs, they hint that human CO2 effect is minor compared to natural greenhouse gases, cast doubt on the surface temperature record, claim global warming stopped in 1988 and invoke water vapor as the most powerful greenhouse gas. These are just minor points on the way to their major conclusion that the sun and cosmic rays are the "main forcing agent in global climate change".

They look at tropospheric and ocean temperature data while ignoring surface air temperature which they say doesn't respond to the solar cycle. This is a surprising claim - Camp & Tung 2007 find a strong 11 year solar cycle signal in global surface temperature records. I discuss the significance of Tung's paper in more detail in Solar cycles and global warming.

However, the real eye opener is when they correlate tropospheric temperature with cosmic rays. The figure below features two graphs. The first graph compares tropospheric temperature (blue) to cosmic rays (red). The second graph removes El Nino, volcanoes and a linear warming trend of 0.14°C per decade. With the warming trend and other "confusions" removed, the negative correlation between cosmic rays and temperature is very high.

The conclusion is obvious - the warming trend over the past several decades has a source other than cosmic rays. Or another way of looking at it - the long term contribution of cosmic rays to global temperatures has been little to nothing (possibly slightly negative). I'm considering whether to use their graph to further debunk the cosmic rays argument.

Lastly, I fail to understand why most seem to forget Lockwood is only the latest in a long line of studies on the topic. Ammann 2007, Foukal 2006, Scafetta 2006, Usoskin 2005, Haigh 2003, Solanki 2003, Stott 2003, Lean 1999, Waple 1999 and Frolich 1998 all find the sun has contributed minimally to global warming over the last 3 decades (more on the sun). And these are just the studies that focus solely on the sun's role. There are a whole host of detection and attribution studies that factor in solar, volcanic, anthropogenic and other forcings and come to the same conclusion. Those are a topic for a future post.

Posted by John Cook at 19:32 PM

Comments

  1. Wondering Aloud at 04:46 AM on 14 December 2007
    I can see why you say it reads like an oped but that isn't very distracting. My question is are they wrong?

    I remember thinking that the Lockwood results seemed strange to me relative to what I knew of the recent history of solar activity.
    [ Response: The oped comment is about as ad hominem as I get (I try to avoid ad hom criticisms which rarely contribute anything useful) - just to register my surprise at the tone of what is meant to be a scientific rebuttal. As for Lockwood, the most controversial element of his paper is that it was even published - generally when you publish a paper, it adds something new to the body of knowledge. Lockwood is covering ground well trod by Ammann 2007, Foukal 2006, Scafetta 2006, Usoskin 2005, Haigh 2003, Solanki 2003, Stott 2003, Lean 1999, Waple 1999 and Frolich 1998 who all find the sun has contributed minimally to global warming over the last 3 decades. ]
  2. We cannot trust the surface data. Its cherry-picked for the purpose of showing warming and there are so many regions where there is no measurement. The balloon and satelite data correlate with eachother. That means they must be reliable. The satelite data it is.

    The satelite/balloon data leaves a lot less to explain in terms of divergence from solar activity. The only years to explain anything at all are probably 78 through 2000. The campaign against SO2 could explain some of this. But the real deal to consider is ACCUMULATING AND DECUMULATING energy lodged in the ocean.

    That solar cycle 23 was not as strong as solar cycle 22 isn't the main point here. For the air temperature to continue to warm solar cycle 23 only had to be strong enough for the ocean to continue to accumulate joules.

    Plus even if 23 was a tad too weak for accumulation over the long haul (that is to say if that strength of cycle was repeated many times) still the momentum of the oceanic circulation could have kept the ocean (and particularly the Far North) warming for a time before that ocean circulation momentum slowed down.

    When the solar scientists say that solar irradiance and air temperature move together in lock step.... but then they say that this only worked until 1978 or 1980 it must be remembered that they are not the ones who compiled the tainted surface data. And when they say this you can be pretty sure they are using the tainted surface data and falling over themselves to make a concession to the mob. Such is the pressure in this field. So we can discount this some since the surface record is tainted.

    In any case while each solar cycle strength is correlated with the air temperature the solar cycle prior is even better correlated. If this was STRICTLY TRUE rather than just a minor observation well then its only natural that the time period FOLLOWING cycle 22 would exhibit the higher air temperature. So it ought not be thought that there is a great deal of an anomaly to explain at all.

    Even that is not the full story. Its all about accumulating joules in the ocean and the air temperature is only a spin-off of that.
  3. "And when they say this you can be pretty sure they are using the tainted surface data and falling over themselves to make a concession to the mob."

    Yeah, keep using that excuse. Every time quote-mined scientist decides to go on record saying that he _doesn't_ dispute the global warming theory, the denialist immediately claimed he's been threatened in unspecified ways by the Worldwide Satanic Conspiracy headed by Al Gore the Antichrist.

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