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Sun's Activity Levels Reconstructed

neutron_p writes "An international team of scientists has reconstructed the Sun's activity over the last 11 millennia and forecasts decreased activity within a few decades. The activity of the Sun over the last 11,400 years, i.e., back to the end of the last ice age on Earth, has now for the first time been reconstructed quantitatively. The scientists have analyzed the radioactive isotopes in trees that lived thousands of years ago. As scientists report in the current issue of the science journal Nature, one needs to go back over 8,000 years in order to find a time when the Sun was, on average, as active as in the last 60 years."

8 of 38 comments (clear)

  1. In other news... by k4_pacific · · Score: 4, Funny

    In order to investigate the issue, NASA has announced that they are sending an unmanned space probe to the sun. In order to avoid the intense heat, they are planning on launching the probe at night.

    --
    Unknown host pong.
  2. Error Bars by CheshireCatCO · · Score: 4, Interesting

    I'm not sure I trust their error bars (they appear on the second plot). Since they're using 10-year averages, they should be removing the effects of the solar cycle. But their sunspot number curves drop below 0 sunspots in several places. A negative number of sunspots is, obviously, unphysical. Also, their data is pretty wildly varying over short timescales (again, solar cycle should be removed) and doesn't match the actual sunspot records from 1610 on very well, either.

    1. Re:Error Bars by Idarubicin · · Score: 3, Informative
      m not sure I trust their error bars (they appear on the second plot). Since they're using 10-year averages, they should be removing the effects of the solar cycle. But their sunspot number curves drop below 0 sunspots in several places. A negative number of sunspots is, obviously, unphysical. Also, their data is pretty wildly varying over short timescales (again, solar cycle should be removed) and doesn't match the actual sunspot records from 1610 on very well, either.

      Unfortunately, most people don't have online access to Nature for the full text of the original article. (For those who do, it's here. If you actually check the data--they have a plot of just the last thousand years comparing various methods--the match with the records from 1610 on is actually quite good.

      They also comment that, "The slightly negative values of the reconstructed SN [sunspot number] during the grand minima are an artefact; they are compatible with SN = 0 within the uncertainty of these reconstructions as indicated by the error bars." I'm not surprised that their calibration might be a bit off when they've had to extrapolate sunspot numbers lower or higher than we've seen with firm data in the last four hundred years.

      --
      ~Idarubicin
  3. Sun activity and climate by StarWynd · · Score: 3, Interesting

    One thing I'm curious about is what effect that the Sun's activity has on climate change. There have been spacecraft studying the sun and more spacecraft studying the magnetosphere and it's interaction with the solar wind. However, it seems that we only have understanding of individual events and the immediate effects of those events. It will be really interesting when some people get a good idea of what long term effects CMEs (coronal mass ejections) and other Sun activity has on our little blue world.

  4. So... by Jerf · · Score: 4, Insightful

    So... we'll schedule the Global Cooling panic for what, 2030-ish? That good for everyone?

    Save your Global Cooling books from the 70s, they'll be invaluable in showing how long it has been a problem even as the Global Warming hysteria is quietly, but thoroughly, whitewashed out of existance (just as the Global Cooling panic has been, as of today).

    See you then!

    (This is about 1/3 humorous, 1/3 a troll, and 1/3 an attempt to get people to be a little less dogmatic and a little more thoughful about climate issues in general. Moderate accordingly, I guess.)

    (PS: I would expect the Earth's temp, if it is affected significantly by the Sun, to lag behind it by several years, because it has one hell of a lot of "thermal inertia".)

    1. Re:So... by mcmonkey · · Score: 3, Funny
      I would expect the Earth's temp, if it is affected significantly by the Sun, to lag behind it by several years, because it has one hell of a lot of "thermal inertia".

      If? IF?? To say the Earth's temp is affected significantly by the Sun is understatement of an absurd degree.

      Yes, there is internal heat from radioactive decay, and perhaps some warming due to tidal forces, but I'd wager 99+% of the Earth's heat comes from the Sun.

      As for "thermal inertia" let's take the extreme case. The Sun goes bye-bye, or its energy output drops to zero. How long do expect the Earth's temp would lag? More practically, seasonal changes in weather--are they more closely tied to the positions of the Earth and the Sun today? Or their positions several years ago, due to "thermal inertia"?

      I'll see you at the next ice age!

  5. Innumeracy warning! by Engineer-Poet · · Score: 4, Informative

    The Sun is approximately 4.5 billion years old. An increase in the average brightness of 30% over that time is equal to 6.7% per billion years, or .00000067% per century. If you think that this will become a measurable change in the next century, you obviously never learned anything worthwhile from a lab course (and nobody should trust you with numerical methods, either).

  6. Re:RTFA by Jerf · · Score: 3, Insightful
    AC says: Except, if you had read the article, you'd see that it quite explicitly says that this study shows that solar activity does not account for the rise is global average temperature since the start of industrial revolution.

    You mean this part?
    Whether this effect could have provided a significant contribution to the global warming of the Earth during the last century is an open question. The researchers around Sami K. Solanki stress the fact that solar activity has remained on a roughly constant (high) level since about 1980 - apart from the variations due to the 11-year cycle - while the global temperature has experienced a strong further increase during that time. On the other hand, the rather similar trends of solar activity and terrestrial temperature during the last centuries (with the notable exception of the last 20 years) indicates that the relation between the Sun and climate remains a challenge for further research.
    Emphasis mine. It does not say anything about whether the activity can account for the temperature. In fact, it quite explicitly disclaims any such claims in either direction. It is too soon. You need to brush up on your science skills, and your ability to read what things say instead of reading what you want them to say. If more climate fearmongers demonstrated these skills, I might actually be willing to join them in their panic. But dogma, dogma, dogma, and carefully selected evidence seems to rule the day.

    Less dogma, more science, please.