This is part four of a series of
posts about climate change. This post also tells how we really should correct
for climate change.
I was told that I should write on
Climate Change again. I complained that I already had done so enough, but I
couldn’t think of anything better to write about, so I looked into the
periodicity of climate change. It is a very interesting subject, and there is
more to be done with it, but there isn’t enough data for everything to be put
together in a neat, compact essay, and the scientists have the same problem. There
are several types of variation in solar heating of the Earth; some are effects
of the Earth’s orbit, while others are matters of the Sun. These three cycles are called Milankovitch
cycles.
Over time the Earth’s orbit becomes
at time rounder and at other times more eccentric (more elongated). The
elongation results in greater differences in temperatures from season to
season; right now the orbit is relatively round.
Then there is axial tilt
(obliquity). Now the Earth’s axis tilts about 23.5 degrees from vertical. Over
time the tilt has been as little as 22.1 degree. The difference isn’t huge, but
less axial tilt leads to colder temperatures near the poles, because lees
sunlight reaches that region during Summer.
Then we have precession, the angle
of the tilt with respect to the place in orbit. At present the tilts most away
from the Sun near the Winter Solstice, when the Earth is closer to the Sun.
This leads to less heating of the major landmasses.
We all know about the sunspot
cycle. Sunspots go from maximum to minimum in an eleven year cycle.
Temperatures tend to be higher during sunspot maxima.
There are several other cycles of
varying length but of less well-known origins. http://en.wikipedia.org/wiki/Solar_variation
. .
|
Cycle length
|
Cycle name
|
Last
positive
carbon-14 anomaly |
Next
"warming"
|
|
232
|
--?--
|
AD 1922
(cool)
|
AD 2038
|
|
208
|
Suess
|
AD 1898
(cool)
|
AD 2210
|
|
88
|
Gleisberg
|
AD 1986
(cool)
|
AD 2030
|
Plus the 2,300 years: Hallstatt
cycle, the 6000 years (Xapsos and Burke, 2009), and a few others. And some work
has been done that indicated that there were harmonic combination of different
cycles. There isn’t any sign that anyone has looked into how one cycle affects
another, but that is something that probably would happen based on the nature
of the different cycles. I couldn’t find anything that indicated a larger cycle
in sunspots, something that would account for the various minima and maxima,
but there probably is a super cycle, or something else is causing the
variations.
I think the total is at least seven
cycles. I was going to chart some together, but seven would be too messy to be
useful. In addition,
‘The sensitivity of climate to cyclical
variations in solar forcing will be higher for longer cycles due to the thermal
inertia of the oceans, which acts to damp high frequencies. Using a
phenomenological approach, Scafetta and West (2005) found that the climate is
1.5 times as sensitive to 22-year cyclical forcing relative to 11-year cyclical
forcing, and that the thermal inertia of the oceans induces a lag of
approximately 2.2 (± 2) years in cyclic climate response in the temperature
data.[35]” from http://en.wikipedia.org/wiki/Solar_variation
It is quite clear that none of the
mechanism that have been proposed for causing climate change are adequate
explanations, but the observations cover only a rather short time with any
reliability; although we have descriptions of climatic conditions tell a good
story for a long time, and we can infer climatic conditions from agricultural
outputs for a considerably longer period. Unfortunately, none of the observations
match the known cycles; although there is some correspondence with harmonics.
“Perry and Hsu (2000) proposed a simple model based on emulating
harmonics by multiplying the basic 11-year cycle by powers of 2, which produced
results similar to Holocene behavior. Extrapolation suggests a gradual cooling
during the next few centuries with intermittent minor warm-ups and a return to
near Little Ice Age conditions within the next 500 years. This cool period then
may be followed approximately 1,500 years from now by a return to altithermal
conditions similar to the previous Holocene Maximum. [36]”
Even if they did an excellent job
we will have to wait to see.
I was hoping that there would be
some relationship between sunspots and longer range patterns, but there isn’t.
Apparently the relationship is coincidental.
|
Solar activity
events and approximate dates
|
||
|
Event
|
Start
|
End
|
|
Homeric minimum[29]
|
950BC
|
800BC
|
|
Oort minimum (see Medieval Warm Period)
|
1040
|
1080
|
|
Medieval maximum (see Medieval Warm Period)
|
1100
|
1250
|
|
Wolf minimum
|
1280
|
1350
|
|
1450
|
1550
|
|
|
1645
|
1715
|
|
|
1790
|
1820
|
|
|
1900
|
present
|
|
Looking at the various cycles, it
becomes clear that there probably will not be an especially warm period or an
ice age in the immediate future, even though several cycles are pointed toward
the ice age. Combining that with the fact that the present level of temperatures
in significantly lower than the Medieval Warm Period, it appears that we will
continue to have rather normal climate with reason for bitching about the cold
of Winter and grousing at the heat of Summer. If you are interested in doing
something about that, then you will be interested in my preceding posts, which
will discuss triggering a new ice age (it isn’t difficult).
Further reading:
Sunspots
Unstoppable solar cycles
Variation in eccentricity
Jupiter and Venus Effect on Earth's
Climate
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