A brief look at the Sun’s influence on Earth’s climate

NASA produces much of the clearest writing I have seen about modern science.  Much of this gets far too little attention, IMO.  For anyone interested in understanding the dynamics of Earth’s climate, esp cutting edge climate science, their websites are a good place to start.

From the website of NASA’s Jet Propulsion Laboratory

ACRIM Satellite

The Active Cavity Radiometer Irradiance Monitor Satellite (ACRIMSAT) Mission will measure Total Solar Irradiance (TSI) during its five-year mission life. The ACRIMSAT spacecraft, carrying the ACRIM III instrument, will be secondary payload on a Taurus vehicle scheduled to launch in December 1999. The instrument, third in a series of long-term solar-monitoring tools built for NASA by the Jet Propulsion Laboratory, will continue to extend the database first created by ACRIM I, which was launched in 1980 on the Solar Maximum Mission (SMM) spacecraft. ACRIM II followed on the Upper Atmosphere Research Satellite (UARS) in 1991. … The Active Cavity Radiometer Irradiance Monitor (ACRIM) I instrument was the first to clearly demonstrate that the total radiant energy from the sun was not a constant.  See the NASA fact sheet for more information.  (source)

From the website of the Active Cavity Radiometer Irradiance Monitor Satellite project

The Earth’s weather and climate regime are determined by the total solar irradiance (TSI) and its interactions with the Earth’s atmosphere, oceans and landmasses.

Evidence from both 29 years of direct satellite monitoring and historical proxy data leaves no doubt that solar luminosity in general, and TSI in particular, are intrinsically variable phenomena.

  • Subtle variations of TSI resulting from periodic changes in the Earth’s orbit (Milankovich cycles: ~20, 40 and 100 Kyrs) cause climate change ranging from major ice ages to the present inter-glacial, clearly demonstrating the dominance of TSI in climate change on long timescales.
  • TSI monitoring, cosmogenic isotope analyses and correlative climate data indicate that variations of the TSI have been a significant climate forcing during the current inter-glacial period (the last ~ 10 Kyrs.).
  • Phenomenological analyses of TSI monitoring results during the past (nearly) three decades, TSI proxies during the past 400 years and the records of surface temperature show that TSI variation has been the dominant forcing for climate change during the industrial era.
  • The periodic character of the TSI record indicates that solar forcing of climate change will likely be the dominant variable contributor to climate change in the future. 

Monitoring TSI variability is clearly an important component of climate change research, particularly in the context of understanding the relative forcings of natural and anthropogenic processes. The requirements for a long-term, climate TSI database can be inferred from a recent National Research Council study which concluded that gradual variations in solar luminosity of as little as 0.25 % was the likely forcing for the ‘little ice age’ that persisted in varying degree from the late 14th to the mid 19th centuries. A centuries-long TSI database will have to be calibrated by either precision or accuracy to a small fraction of this value to be of any use in assessing the magnitude of solar forcing.   (source)

For more information

(A)  Monitoring the Sun and Its Radiation to improve our understanding of Earth’s climate variations“, Richard C. Willson (Columbia University), on NASA’s ACRIM website, 37 slides.  I suggest starting at slide #14.

(B)  Articles (most from peer-reviewed publications) about the solar cycle appear in section 5 on the FM reference page about Science & nature – studies & reports.  They show the many sides to this, one of the least well-understood aspects of the climate sciences.

(C)  Articles about the sun from the FM site:

  1. Worrying about the Sun and climate change: cycle 24 is late, 10 July 2008
  2. Update: is Solar Cycle 24 late (a cooling cycle, with famines, etc)?, 15 july 2008
  3. Solar Cycle 24 is still late, perhaps signalling cool weather ahead, 2 September 2008
  4. Update on solar cycle 24 – and a possible period of global cooling, 1 October 2008
  5. This week’s report on the news in climate science, 7 December 2008
  6. Weekend reading recommenations about climate change, 13 December 2008
  7. An important new article about climate change, 29 December 2008
  8. About the recent conference ”Solar Activity during the onset of Solar Cycle 24″, 3 January 2009
  9. NASA: Sun undergoing a “deep solar minimum”, 13 April 2009
  10. The Unusually Quiet Sun finally gets some attention, 23 April 2009


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4 thoughts on “A brief look at the Sun’s influence on Earth’s climate”

  1. Maybe the sun is starting to stir? Images of what might be two active regions.
    Fabius Maximus replies: For a description of this picture, see Anthony Watts at Watts Up with That:

    NASA’s STEREO-B spacecraft is monitoring an active region hidden behind the sun’s eastern limb. On May 5th, it produced an impressive coronal mass ejection (movie) and a burst of Type II radio emissions caused by a shock wave plowing through the sun’s outer atmosphere. … Activity continued apace on May 6th with at least two more eruptions. Furthermore, recent UV images from STEREO-B reveal not just one but two active regions: image below.

    The global warming cheerleaders are getting desperate, watching the late arrival of solar cycle 24. First we have this wonderful example of scientists doing propaganda from “Sun Oddly Quiet — Hints at Next ‘Little Ice Age’?“, National Geographic, 4 May 2009:

    “But researchers are on guard against their concerns about a new cold snap being misinterpreted. “[Global warming] skeptics tend to leap forward,” said Mike Lockwood, a solar terrestrial physicist at the University of Southampton in the U.K. (Get the facts about global warming.)” He and other researchers are therefore engaged in what they call “preemptive denial” of a solar minimum leading to global cooling.

    Then we see this absurdity: “Big Solar Flare Portends Sun’s Return to Normal“, Wired, 6 May 2009. As if one CME, even a large one, tells us anything about the overall cycle.

    “One swallow does not make a summer.”
    — Aristotle in Nichomachean Ethics)

  2. Daniel Herkes

    The sun is the source of all of the energy on earth. The amount of infrared light trapped in the earths atmosphere has a lot to do with the amount of IR the sun puts out, and the level of carbon dioxide and methane that help trap the heat.

  3. Follow-up to MTJ in comment #1:

    MTJ’s comment and the article in Wired show the “cheerleading” for increased sunspot activity, perhaps to ward off fears that Solar Cycle 24 will be quiet — which might result in a period of cooling for Earth.

    This story (the new active regions), like so many before, was unwarranted. On May 9 Spaceweather reports:

    “MAGNETIC FROTH: The farside sunspot that unleashed a powerful CME on May 5th is finally rotating into view. Except it is not a sunspot. The blast site appears to be in a state of decay with only some patches of bright magnetic froth marking where a sunspot group might have been.”

    Note that the Wired article was mis-leading in several respects. “The sun has a new spot, and it could signal the long-awaited beginning of the next solar cycle.” The sun did not have a new spot, and even a new spot or two does not signal the beginning of a new cycle.

  4. My sense is that the AGW crowd is becoming ever more strident as they try to keep the wheels on their policy wagon. Getting CO2 declared a pollutant by EPA was critical, but only a first step. No matter what the hard data suggests, I expect them to remain implacable in their “Great March Forward”. I can identify the mandarins, Chu, Gore, but who is the counterpart to Chairman Mau?

    I know my paranoia is showing, but, “Some circumstantial evidence is very convincing, as when one finds a trout in the milk.”…Voltaire

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