This is an update to my post of 10 July : Worrying about the Sun and climate change – cycle 24 is late. Here is a brief summary of the threat; see that post for details:
Solar cycle #24 is on my list of things to watch. The next 11-year solar cycle— number 24 — has not yet started. It is a little late, and getting later. Nothing significant yet, but it could quickly become a major geopolitical factor. We may have a problem if it does not start by September. A late cycle may be a “small” cycle, one with few sunspots and low levels of solar activity. Such periods have often accompanied periods of cold weather on Earth. Cooling means famines.
These reports describe the latest forecasts, from the International Workshop “Solar Variability, Earth’s Climate and the Space Environment“, sponsored by NASA, held 1 – 6 June 2008.
- A summary of the workshop’s results. Here are abstracts of the papers presented.
- “Global Climate Change: Is the Sun to blame?“, Sami K. Solanki, 3 June 2008
- “What’s Wrong with the Sun? (Nothing)“, NASA, 11 July 2008 — A rebuttal from staff at NASA.
Excerpts of these reports
I. “Sun goes longer than normal without producing sunspots“, Montana State University News Service, 9 June 2008 — This story is the basis for many news reports, including ScienceDaily. Excerpt:
The sun has been laying low for the past couple of years, producing no sunspots and giving a break to satellites.
That’s good news for people who scramble when space weather interferes with their technology, but it became a point of discussion for the scientists who attended an international solar conference at Montana State University. Approximately 100 scientists from Europe, Asia, Latin America, Africa and North America gathered June 1-6 to talk about “Solar Variability, Earth’s Climate and the Space Environment.”
The scientists said periods of inactivity are normal for the sun, but this period has gone on longer than usual. “It continues to be dead,” said Saku Tsuneta with the National Astronomical Observatory of Japan, program manager for the Hinode solar mission. “That’s a small concern, a very small concern.” {FM: is this a pun on “small”?}
… Dana Longcope, a solar physicist at MSU, said the sun usually operates on an 11-year cycle with maximum activity occurring in the middle of the cycle. Minimum activity generally occurs as the cycles change. Solar activity refers to phenomena like sunspots, solar flares and solar eruptions. Together, they create the weather than can disrupt satellites in space and technology on earth. The last cycle reached its peak in 2001 and is believed to be just ending now, Longcope said. The next cycle is just beginning and is expected to reach its peak sometime around 2012. Today’s sun, however, is as inactive as it was two years ago, and scientists aren’t sure why.
“It’s a dead face,” Tsuneta said of the sun’s appearance. Tsuneta said solar physicists aren’t like weather forecasters; They can’t predict the future. They do have the ability to observe, however, and they have observed a longer-than-normal period of solar inactivity. In the past, they observed that the sun once went 50 years without producing sunspots. That period coincided with a little ice age on Earth that lasted from 1650 to 1700.
II. “Global Climate Change: Is the Sun to blame?“, Sami K. Solanki, 3 June 2008 – He is Managing Director of Max Planck Institute for Solar System Research and Contributing Author of the Intergovernmental Panel on Climate Change (IPCC). Summary:
The Earth is heating up. For the last century it has relentlessly grown warmer, in spite of short periods of respite. This global change is leaving its mark and the predictions for the future are not very comforting. As the Earth has heated up, so has the debate on the causes of global change. Opposing camps fight over whether the drivers are man-made or natural.
The prime natural cause for explaining global warming is the Sun. It is a restless star that shows a wide variety of transient and active phenomena, such as the continuously changing hot corona, energetic flares and immense coronal mass ejections. Along with these more violent events, the Sun displays a permanent variation of its brightness, which is thought to influence the Earth’s climate. Paths by which the Sun could affect climate are outlined in this talk and the question is considered to what extent is the Sun responsible for the global warming seen in the last decades.
III. “What’s Wrong with the Sun? (Nothing)“, NASA, 11 July 2008 — A rebuttal from scientists at NASA. Excerpt:
Stop the presses! The sun is behaving normally. So says NASA solar physicist David Hathaway. “There have been some reports lately that Solar Minimum is lasting longer than it should. That’s not true. The ongoing lull in sunspot number is well within historic norms for the solar cycle.” … But first, a status report: “The sun is now near the low point of its 11-year activity cycle,” says Hathaway. “We call this ‘Solar Minimum.’ It is the period of quiet that separates one Solar Max from another.”
Although minima are a normal aspect of the solar cycle, some observers are questioning the length of the ongoing minimum, now slogging through its 3rd year. “It does seem like it’s taking a long time,” allows Hathaway, “but I think we’re just forgetting how long a solar minimum can last.” In the early 20th century there were periods of quiet lasting almost twice as long as the current spell.
Hathaway has studied international sunspot counts stretching all the way back to 1749 and he offers these statistics: “The average period of a solar cycle is 131 months with a standard deviation of 14 months. Decaying solar cycle 23 (the one we are experiencing now) has so far lasted 142 months–well within the first standard deviation and thus not at all abnormal. The last available 13-month smoothed sunspot number was 5.70. This is bigger than 12 of the last 23 solar minimum values.”
In summary, “the current minimum is not abnormally low or long.”
Afterword
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To read other articles about these things, see the FM reference page on the right side menu bar. Of esp relevance to this topic:
- About Science & Nature – my articles
- About Science & nature – studies & reports — other useful sources of information.
Posts on the FM site about posts about the solar cycle:
- Worrying about the Sun and climate change: cycle 24 is late, 10 July 2008
- Update: is Solar Cycle 24 late (a cooling cycle, with famines, etc)?, 15 july 2008
- Solar Cycle 24 is still late, perhaps signalling cool weather ahead, 2 September 2008
- Update on solar cycle 24 – and a possible period of global cooling, 1 October 2008
- This week’s report on the news in climate science, 7 December 2008
- Weekend reading recommenations about climate change, 13 December 2008
- An important new article about climate change, 29 December 2008
- My “wish list” for the climate sciences in 2009, 2 January 2009
- About the recent conference ”Solar Activity during the onset of Solar Cycle 24″, 3 January 2009
