While the IPCC doesn’t have an answer for why there has been no statistical increase in global temperatures for going on 17 years, they don’t think the Sun has been a significant factor. They generalize that volcanoes, deep ocean warming, and particulate matter in the atmosphere may be the cause.
Copy of Woodcutting by TheGuardian.com by Duncan Clark
I believe the IPCC gets this wrong. Beginning somewhere in the second quarter of the twentieth century, the Earth began experiencing a “Modern maximum” in solar activity. Sunspots, that are a proxy for solar activity, began a climb roughly at the time of Solar Cycle 15. Solar Cycle 15 sunspots peaked at 105. The climb continued for the next four solar cycles. Solar Cycle 19 had a peak sunspot number of 202. Solar Cycle 19 ran from April 1954 to October 1964. Solar cycles 20, 21, 22 and 23 showed a decline from the high point of cycle 19, but they were well above the norm. The so-called “Modern maximum” does not appear to have any equivalent in the record all the way back to the 1700s. The global temperatures climbed in unison with the increased solar activity. Now we have entered more typical level of solar activity with the presence of Solar Cycle 24. Cycle 24 is expected to peak at
The table below lists the Solar Cycles from #12 which began in December 1878 to the current Solar Cycle 24 which began on December 2008. Nominal cycle length is 11 years (132 months).
|Cycle #||Peak SSN||Cycle History|
|12||75||Dec 1878||March 1890||136|
|13||88||March 1890||Feb 1902||143|
|14||65||Feb 1902||Aug 1913||128|
|15||105||Aug 1913||Aug 1923||120|
|16||78||Aug 1923||Sept 1933||121|
|17||120||Sept 1933||Feb 1944||125|
|18||152||Feb 1944||April 1954||122|
|19||202||April 1954||Oct 1964||126|
|20||110||Oct 1964||June 1976||140|
|21||165||June 1976||Sept 1986||123|
|22||158||Sept 1986||June 1996||117|
|23||121||June 1996||Dec 2008||149|
Historically, when the Solar Cycles exhibited low activity, such as Cycles 5,6 and 7, the global temperatures dropped. That period was called the Dalton Minimum. An earlier period, called the Maunder Minimum, during the 17th century where almost no sunspots were recorded, was a period of exceptionally cold weather. During the 17th century, sunspots were observed and recorded but not with the rigorous programs that were used in subsequent years.(Click on charts for clarity.)
Charts by Climate4You.com
The escape from the Modern maximum and the advent of Cycle 24 with its relatively low activity appears to have ushered in a readjustment of global temperatures.
What to make of this?
First off, the correlation of global temperature and solar activity seems obvious. Second, the globe has been warming for 10,000+ years since the last ice age and it has cycled between ice and interglacial periods at least 5 times in the last 1million or so years. (See a discussion of the glacial and interglacial periods by clicking here.) And it has not been man-made CO2 that causes these cycles. It is seems logical that this must be Sun related.
The naysayers point out that the solar radiation received at our upper atmosphere changes little from cycle to cycle. No question that it maxed out during the Modern maximum but they don’t think the reduction is enough to make any difference. The naysayers are just not people from the IPCC but some pretty heavyweight solar scientists that appear to be skeptical of the man-made global warming theory.
Chart from Climate4You.com
There are theories that state the Ultra Violet radiation varies widely over a solar cycle and it is not properly accounted for. The Chiefio post “More TSI variation and big UV variance“ concludes that the amount of UV solar radiation is vastly underreported. Proxy evidence suggests that it swings as much as 25%. It is largely blocked in the upper atmosphere by ozone where it heats the upper atmosphere. More study is required to work out the effect of UV but it looks promising.
There are a number of theories that say the Sun plays a primary role in global temperatures.
The Svensmark theory that low solar activity results in a weaker interplanetary magnetic field, that in turn allows greater numbers of high-energy gamma rays into the Earth’s atmosphere. These particles collide with oxygen molecules, for example, breaking the molecule up into particles that act as building blocks for cloud nuclei The clouds increase the albedo, and this results in more of the Sun’s radiation being reflected back into space. Note the correlation of gamma rays increasing as the solar cycle activity decreases in the following chart.
Chart from Climate4You.com
This theory is undergoing testing at CERN. The most recent report from CERN can be viewed by clicking here.
The Hockey Schtick posting “Paper finds another amplification mechanism by which the Sun controls climate“ reports”:
“A lecture by professor Hiroko Miyahara of the University of Tokyo provides additional support to the Svensmark theory of cosmoclimatology, finding that both solar geomagnetic activity and the polarity of geomagnetic activity have significant effects upon cosmic rays and cloud formation. The polarity of solar geomagnetic activity flips with a 22-year cycle, with periods of negative polarity [such as the current solar cycle] having a greater effect upon cosmic rays and cloud formation.”
There are a number of other theories that discuss solar amplification. If I can find some time to study them, I will report my findings.