How The Sun Could Control Earth’s Temperature
by
Stephen Wilde.
Introduction:
The Holy Grail of climatology has always been to ascertain whether, and if so
how, the sun might affect the Earth’s energy budget to cause the climate swings
observed throughout history despite the apparent inadequacy of the tiny
variations in Total Solar Irradiance (TSI) that occur from one series of solar
cycles to another.
I think that there is a plausible mechanism whereby those tiny solar changes
could be amplified enough by natural features of the Earth’s climate system to
achieve the observed outcome.
This article also shows how the theory of Anthropogenic Global Warming
(AGW) has failed to account for the various real world observations that have
been accumulating since the late 1990s. The ideas set out in this article provide
a potential solution and progress my earlier New Climate Model found here:
New Climate Model (First Review)
by focusing on the effect of solar variability.
Evidence for the failure of current theories and climate models.
i)
The level of CO2 in the atmosphere continues to rise slowly but the
tropospheric warming trend appears to have stalled since 1998 and may be
about to change to a cooling trend. AGW theory anticipated an increasing rate
of tropospheric warming as CO2 accumulated in the atmosphere but that is
clearly not happening. Much has been made of recent years having been warmer
in the troposphere than other years in the temperature record but since we are
near the top of a natural warming curve similar to the Mediaeval Warm Period
or the Roman Warm Period that is hardly a cause for concern. Indeed there is
some evidence that we have not yet matched the warmth of the Mediaeval
Warm Period.
ii)
During the late 20
th
century warming trend the stratosphere was observed to
cool and that was also supposed to be in accordance with AGW. However since
the 90s that cooling has ceased and the stratospheric temperature trend is now
one of slight warming:
http://www.jstage.jst.go.jp/article/sola/5/0/53/_pdf
“The evidence for the cooling trend in the stratosphere may need to be revisited.
This study presents evidence that the stratosphere has been slightly warming
since 1996.”
iii)
The jetstreams moved poleward in accordance with AGW theory:
http://www.msnbc.msn.com/id/24228037/
“From 1979 to 2001, the Northern Hemisphere's jet stream moved northward on
average at a rate of about 1.25 miles a year, according to the paper published
Friday in the journal Geophysical Research Letters.”
However, it is becoming clear that since at least 2001 the jets have been moving
back equatorward again despite increasing CO2 levels.
iv)
During the warming spell global cloudiness decreased as did global albedo
(reflectivity as seen from space) which is consistent with poleward shifting jets
but the Earthshine project now shows us that both global cloudiness and global
albedo are increasing again since the late 90s:
http://bbso.njit.edu/Research/EarthShine/literature/Palle_etal_2006_EOS.pdf
Increased cloudiness and albedo are indications that the climate system is
receiving less solar energy overall and is therefore a sign of reducing energy
content for the system as a whole contrary to AGW theory.
It will be interesting to see what happens to ocean heat content over the next
few years. There are suggestions that it recently peaked and may start to trend
down and if does turn downwards that will confirm the significance of the
cloudiness and albedo changes.
v)
Standard climatology proposes that, when the sun is more active, all the
layers of the atmosphere warm and, when the sun is less active, all the layers of
the atmosphere cool. That did not happen during the recent warming spell.
Whilst the thermosphere and troposphere warmed from the more active sun the
stratosphere and mesosphere actually cooled. Now that the sun is less active that
cooling trend in the stratosphere has changed to a warming trend so it is likely
that the stratosphere and mesosphere actually respond to changes in the level of
solar variability oppositely to the thermosphere and troposphere as part of an
entirely natural process. Standard climatology has proposed that human CO2
and / or CFCs upset what was assumed to be the natural order of things. This
article will try to show that that basic assumption which has been incorporated
into all current climate models and theories may be wrong.
The false premise.
Before I describing what I believe to be the truth about the solar effect on the
global energy budget I must first set out exactly what has gone wrong because
only by understanding that can a reader evaluate the merit of my alternative
hypothesis.
It has long been assumed that stratospheric temperatures are set by the heat
generating effect of incoming solar ultra violet radiation (UV) on ozone in the
stratosphere. When the sun is more active there is more UV and the stratosphere
becomes warmer. The amounts of ozone and UV are generally sufficient to
maintain a temperature inversion from the tropopause up through the
stratosphere to the stratopause.
However that is as far as standard climatology and AGW theory go. Everything
is based on the premise that since the UV/ozone reactions lead to a warmer
stratosphere then more UV from a more active sun should make the stratosphere
even warmer. I suspect that premise to be mistaken.
There are two substantial problems with that scenario:
i) The stratosphere and the mesosphere actually cooled when the sun was more
active and are now warming now that the sun is less active. There must be
something else going on to account for that.
ii) The jet streams moved poleward and the
polar vortexes shrank
when the
sun was more active. That is a critical point for diagnostic purposes and I need
to explain in some detail why it is so critical.
Jet Stream Behaviour
.
(a) The conventional view:
The standard explanation for jet stream shifts relies solely on differential
heating of the stratosphere by UV warming of ozone in the stratosphere.
However I think that may be only a part of the picture and only one component
of a larger scenario that additionally requires the involvement of a separate solar
proton effect in the upper atmosphere and modulating effects from the oceans.
Thus it is normally proposed that a more active sun warms the stratosphere
above the equator more than the stratosphere above the poles (but both locations
are supposed to warm) so that the height of the tropopause at the equator
descends and pushes the jets poleward. I do not consider that to be a sufficient
explanation because:
i) Taking the stratosphere as a whole (rather than splitting it into latitudinal
sections) it actually appears to have cooled during the late 20
th
century period of
more active sun and now appears to be warming slightly with a less active sun.
ii) If the stratosphere above the poles also warmed as proposed at the same time
as the stratosphere above the equator warmed then the tropopause at the poles
would also have descended and would have provided more resistance to the
poleward shift of the jets than was actually observed.
iii) The distance of the jet stream latitudinal shifting from the peak of the
Mediaeval Warm Period to the depths of the Little Ice Age is in my opinion far
greater than could be explained simply by the small differential between solar
effects on UV at the equator and solar effects on UV at the poles.
iv) The solar effect on stratospheric ozone on the height of the tropopause at the
equator would be heavily modulated by ocean surface temperatures so that the
poleward pressure on the jet streams would be inconsistent. In fact I think that
the effect of ocean sea surface variability on the height of the tropopause at the
equator would be far greater than the solar UV effects.
v) The actual shrinking of the polar vortexes seems unlikely just from poleward
pressure from the slightly lower tropopause at the equator given that the polar
tropopause should also have been lowering to some extent (but less) at the same
time. More likely some additional process from above encouraged the polar
vortex to shrink at the same time as the jets were pushed poleward.
(b) The alternative view:
My proposition is that instead the latitudinal shifts are a result of two separate
forces acting together (hence the high mobility of the jets latitudinally) when the
sun is more active with one being a cooling effect at high levels over the poles
pulling the jets poleward
and the other being a warming effect at low levels over
the equator pushing the jets poleward at the same time.
The cooling effect
appears to be dominant over longer time periods to give the observed cooling of
the stratosphere and mesosphere when the sun is more active. Nonetheless there
is still
overall system warming with the more active sun
because of the extra
energy going into the oceans due to the jets shifting poleward thereby reducing
total cloudiness and albedo as shown in the illustration at the head of this
article.
In this article I am discussing the global net energy balance of the stratosphere
and mesosphere combined which is a product of the balance between top down
The following events occur when the sun is more active:
i) An increase in solar radiation warms the thermosphere thereby reducing the
temperature differential between mesopause and stratopause so that the
mesopause falls in height.
ii) An increase in solar protons destroys more ozone in the mesosphere which
cools.
iii) The cooling mesosphere draws energy up from the stratosphere which also
cools despite the warming effect of extra ultra violet radiation acting on the
ozone in the stratosphere.
iv) The cooling stratosphere increases the temperature differential between
surface and stratosphere so the tropopause rises thereby drawing the air
circulation systems in the troposphere poleward as the polar vortex shrinks
horizontally but deepens vertically.
v) The poleward shift of the air circulation systems allows more solar energy
into the oceans and onto the land by reducing cloud quantities and albedo so the
troposphere warms.
Note however that the observed temperature effect within the troposphere will
also be modulated by the sea surface temperatures at the time which can either
supplement or offset the effect of the solar changes.
3) When the sun is less active.
This is what must happen to accord with observations. A situation that mirrors
all that happens when the sun is more active.
Summary:
By applying the above described mechanism an active sun causes the jets to
move poleward thus ‘opening the window blinds’ for an increase in solar energy
reaching and entering the oceans with the system showing a net energy gain
overall.
A quiet sun causes the jets to move equatorward thus ‘closing the window
blinds’ for a decrease in solar energy reaching and entering the oceans with the
system showing a net energy loss overall.
This is the climate narrative that best fits real world changes over the past ten
years together with the conditions that prevailed pre 2000.
Thus do tiny changes in solar activity nonetheless produce significant energy
budget effects on the Earth system by varying the strength and intensity of the
proton bearing solar wind.
With solar protons being charged particles this scenario also provides support
for those who have perceived climate correlations with the strength of the solar
wind and with variations in the Earth’s magnetic fields.
There are also implications for the variability in the size of the polar ozone
holes but that is beyond the scope of this article.
Copyright: Stephen Wilde, 25
th
October 2010.
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