The Sun and Climate: Correlations and Extremes

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The Sun and ClimateCorrelations and Extremes

• Continuing Question Does solar variability
  effect Earths climate?
• What are the indicators? -- correlations
• The extreme case was the Maunder Minimum was
  Earths climate altered?

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Class Paper title/description

• It is time to start thinking about your class
  paper
• please research various topics that are related
  to the class material.
• Turn in to me a tentative title or subject and a
  brief description
• No more than a page, but provide enough
  information for me to be able to critique it
• Due November 5 (3 weeks from today)
• More details are currently available on the
  course website
• The actual course paper will be due on the last
  day of class. The details are now posted on the
  course website.

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Class Presentation

• It is time to start thinking about your class
  presentation
• please research various topics that are related
  to the class material.
• The topic of your presentation may be the same as
  the topic for your term paper, but it does not
  have to be
• The presentation should be 7 minutes 3 minutes
  of open discussion and questions
• A sign-up sheet is available for you to pick the
  day of your presentation
• More details will appear on the course website
  shortly

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Correlation Coefficient - 0.8
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Correlation Coefficient 0.1
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Extreme Case The Maunder Minimum

• The Maunder minimum was a period from the
  1645-1715 in which very few sunspots were
  recorded
• First pointed out in the 1970s by Tucson solar
  physicist Jack Eddy
• Only 50 total sunspots, compared to 50,000 over
  a similar time interval in the 1900s
• There is some evidence showing that the Sun may
  have been a bit larger during this period
• Rotates more slowly
• Less luminous

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Was Earths Climate altered?

• During the Maunder minimum, there was a period of
  extremely cold winters in Northern Europe
• The Little Ice Age
• Was it worldwide?
• Today, we are in a period known as the Modern
  Maximum where there are more sunspots than
  average
• There is evidence from the astronomical
  observations that our Sun is more active today
  (in Xray and UV) than other similar stars
• Perhaps during the Maunder minimum the Sun was
  less luminous and less energy arrived at Earth
  hence it was cooler

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The Sun is slightly dimmer during sunspot minimum
as seen by recent, highly sensitive (but not
inter-calibrated!) measurements
Solar Energy arriving at Earths orbit The Solar
Constant
?
?
Sunspot Minimum
Sunspot Minimum
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The River Thames frozen over during a period
within the Little Ice Age as depicted in this
painting by Abraham Hondius
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Solar Cycles and Earth Cycles

• Are there any life cycles on Earth that may be
  related to solar cycles?
• Does it seem reasonable that the Sun should be
  related to these?
• Are animals sensitive to extreme solar activity
  such as geomagnetic storms?

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Mammal species and cycles

• True cycles in animal populations are rare.
• According to an article by Sinclair and Gosline,
  there have been no reported cycles in the
  southern hemisphere, or equatorial regions.
• There are known cycles in the northern
  hemisphere, with the length of the cycle
  depending on the mass of the mammal
• Longer cycle for larger animals.

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The snowshoe hare

• Long-term records obtained from tree-ring data
  (notches produces as the rabbits eat the birch
  trees)
• Population varies with an average 10-year cycle
  (varies by a few years on either side)
• The amplitude of this cycle varies with latitude
• There are no known cycles at lower latitudes
  (equatorial regions)
• Is it just a coincidence that the sunspot number
  also varies with a similar cycle?

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The Case of the Sperm Whale

• It is well known that Sperm whales take long and
  well-directed journeys through the ocean
• They may use a global positioning system to
  navigate
• The Earths magnetic field, which can be sensed
  within the oceans is a natural navigation tool
  for the whales

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Sperm whale strandings

• Occasionally sperm whales become stranded or even
  beached (stranding events)
• This data has been recorded for over 200 years
• The strandings can be compared against a time
  series of sunspot number

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• The direction of this correlation (as weak as it
  is) is
• More strandings ? more sunspots
• Fewer strandings ? fewer sunspots
• Geomagetic storms are more frequent during
  periods of numerous sunspots
• The suggestion is the that Geomagnetic storms may
  affect the navigation of sperm whales

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Homing pigeons

• The problem with the Sperm whale / geomagnetic
  storm link is that there are no controlled
  experiments
• i.e. we cannot let loose a bunch of sperm whale
  during a geomagnetic storm and see what happens
• The homing pigeon is a somewhat different story
• There is evidence that homing pigeons do not
  return to their home roost when let loose during
  geomagnetic storms
• This is controversial, however!

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Next Week

• Next week we will watch a movie Solar Max which
  runs for about 50 minutes, so please arrive on
  time.