Special Report: Rare Spotless Sun

What does an absence of sunspot activity mean for us?

Spotless Sun
A current image of a very quiet looking sun; image courtesy NASA
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By Kevin Roeten:

Kevin Roeten
Science Editor

The absence of sunspot activity means we’re more likely to experience colder weather in the coming years, not global warming

Meteorologist Paul DorianVencore Weather, has determined solar-cycle 24 continues to transition away from its solar maximum and towards the next solar minimum.  There have already been 11 spotless days during 2017. This follows 32 spotless days occurring during the latter part of 2016.  The spotless surface on the sun will increase in frequency over the next few years giving the next solar minimum. It’s estimated in late 2019-2020 this minimum will occur. The current solar cycle is the third weakest since record keeping began in 1755 and it continues this trend since solar cycle 21 peaked in 1980. Therefore, cosmic rays are strongest during this time of almost no sunspots.

One of the impacts of low.solar activity is the increase of cosmic rays penetrating into the upper atmosphere, and this has been irrationally fixed to ‘global warming’, and the reduction of ozone. Results from a global climate model including an interactive parameterization of stratospheric chemistry show how upper stratospheric ozone changes may amplify observed, 11-year solar cycle irradiance changes to affect climate. In the model, circulation changes initially induced in the stratosphere subsequently penetrate into the troposphere, demonstrating the importance of the dynamical coupling between the stratosphere and troposphere. The model reproduces many observed 11-year oscillations, including the relatively long record of geopotential height variations. It describes these oscillations are driven by solar variability.

Comparison of all solar cycles since 1755 in terms of accumulated sunspot number anomalies from the mean value. Plot courtesy publication cited by authors Frank Bosse and Fritz Vahrenholt. Cosmic rays have been steadily increasing in recent months during historically weak solar cycle 24 which is heading towards the next solar minimum; courtesy spaceweather.com.

One Of Weakest Solar Cycles Since 1755

A recent publication analyzed the current solar-cycle and has found when sunspot anomalies are compared to the mean for the number of months after cycle start, there have been only two weaker cycles since observations began in 1755.  Solar-cycle 24 began in 2008 after a long and deep solar minimum putting eight years into the current cycle.  The plot (below) shows accumulated sunspot anomalies from the mean value after cycle start (97 months ago), and only solar-cycles 5 and 6 had lower levels going back to 1755.  The mean value is noted at “zero,” and solar cycle 24 is running 3817 spots less than the mean.  The seven cycles preceded by solar-cycle 24 had more sunspots than the mean.

Daily observations of the number of sunspots since 1 January 1900 according to Solar Influences Data Analysis Center (SIDC). The thin blue line indicates the daily sunspot number, while the dark blue line indicates the running annual average. Last day shown: 31 January 2017. (Graph courtesy climate4you.com)

Cosmic Ray Increases

One of the consequences of extended periods of low solar activity is the result in increased stratospheric radiation. As sunspot activity goes down, there is an increase in cosmic rays penetrating the upper atmosphere.  Cosmic rays are high-energy photons and subatomic particles accelerated in our direction by distant supernovas and other events in the Milky Way galaxy. Usually, cosmic rays are held at bay by the sun’s magnetic field, which envelops and protects all the planets in the Solar System. But the sun’s magnetic shield is weakening as the current solar cycle heads towards the next solar minimum and this allows more cosmic rays to reach the atmosphere.

Spaceweather.com has monitored radiation levels in the stratosphere with weekly high-altitude balloon flights over California. The findings confirm the hypothesis cosmic rays have been increasing in recent months as solar cycle 24 heads towards the next solar minimum. There actually has been an 11% increase of stratospheric radiation since March 2015-through late 2016.  The sensors sent to the stratosphere track increasing levels of radiation by measuring X-rays and gamma-rays. These are produced by the crash of primary cosmic rays into the atmosphere. The increase in the penetration of cosmic rays into the atmosphere is expected to continue for years, as solar activity plunges toward the next solar minimum expected around 2019-2020.

Cosmic Rays And Cloud Formation

Researchers believe cosmic rays hitting the atmosphere create aerosols which seed clouds, and forming more clouds. This would make cosmic rays an important player in weather and climate.  Researchers have shown laboratory experiments have supported the idea cosmic rays seed clouds.

study published in the Aug. 19th, 2016 issue of Journal of Geophysical Research: Space Physics supports the idea of an important connection between cosmic rays and clouds. According to spaceweather.com, a team of scientists from the Technical University of Denmark, DTU, and the Hebrew University of Jerusalem has linked sudden decreases in cosmic rays to changes in cloud cover. These rapid decreases in the observed galactic cosmic ray intensity are known as “Forbush Decreases” and usually occur following Coronal Mass Ejections, CMEs, during high solar activity. When the sun is active (i.e., solar storms, CMEs), the magnetic field of the plasma solar wind sweeps some of the galactic cosmic rays away from Earth.  In periods of low solar activity, more cosmic rays bombard the earth.  The term “Forbush Decrease” was named after the American physicist Scott E. Forbush.

The research team led by Jacob Svensmark, of DTU, who identified the strongest 26 “Forbush Decreases” between 1987 and 2007, and looked at ground-based and satellite records of cloud cover to see all the changes. Their summarized conclusions: “[Strong “Forbush Decreases”] cause a reduction in cloud fraction of about 2 percent corresponding to roughly a billion tons of liquid water disappearing from the atmosphere.”

Other Cosmic Ray Impacts

In addition to its impact on clouds and climate, an increase in cosmic ray penetration during periods of low solar activity can make this a more dangerous time for astronauts. The increase in potent cosmic rays can easily shatter a strand of human DNA. Also, during years of lower sunspot number, the sun’s extreme ultraviolet radiation (EUV), drops and the  upper atmosphere cools and contracts. With sharply lower aerodynamic drag, satellites have less trouble staying in orbit. On the other hand, space junk tends to accumulate, making the space around Earth a more complicated place to navigate for astronauts.

Sunspot numbers for solar cycles 22, 23 and 24 which shows a clear weakening trend; courtesy Dr. David Hathaway, NASA/MSFC

Consequences of weak solar cycles

There can be important consequences from weak solar-cycles. This is especially true if they are part of a long-term pattern.  First, this particular weak solar-cycle has resulted in rather benign “space weather” in recent times with weaker-than-normal geomagnetic storms. By all Earth-based measures of geomagnetic and geoeffective solar activity, this cycle has been extremely quiet. However, while a weak solar-cycle suggests strong solar storms will occur less often than during stronger and more active cycles, it does not rule them out entirely. The famous “superstorm” Carrington Events of 1859 occurred during a weak solar cycle [#10]. Most solar flares and significant geomagnetic storms tend to occur in the declining phase of the solar cycle.

400 years of sunspots with Maunder and Dalton Minimums; courtesy wikipedia

It’s well understood solar activity has a direct impact on temperatures at very high altitudes in a part of the atmosphere called the thermosphere. This is the biggest layer of the atmosphere which lies directly above the mesosphere and below the exosphere. Thermospheric temperatures increase with altitude due to absorption of highly energetic solar radiation and are highly dependent on solar activity.

It’s safe to say weak solar activity for a very prolonged period of time (several decades) can have a cooling impact on global temperatures in the troposphere which is the bottom-most layer of atmosphere. There have been two notable historical periods with decades-long episodes of low solar activity. The first period is known as the “Maunder Minimum”, named after the solar astronomer Edward Maunder, and it lasted from around 1645 to 1715. The second one is referred to as the “Dalton Minimum”, named for the English meteorologistJohn Dalton, and it lasted from about 1790-1830. Both of these historical periods coincided with colder-than-normal global temperatures in an era that is now referred to by many scientists as the “Little Ice Age”. One of the reasons prolonged periods of weak solar activity may be associated with colder global temperatures has to do with a complicated relationship between solar activity, cosmic rays, and clouds on Earth.  Research studies in recent years have found in times of low solar activity more cosmic rays reach the atmosphere. This leads to an increase in certain types of clouds that cool the Earth.


The increasingly likely outcome for another historically weak solar cycle continues the recent downward trend in sunspot cycle strength that began over thirty years ago during solar-cycle 22. When this trend continues for the next few cycles, then you’ll see increasing talk of another “grand minimum” for the sun, which translates to an extended decades-long period of low solar activity. Some solar scientists are already predicting that the next solar cycle will be even weaker than this current one which has been historically weak. However, it is just too early for high confidence in those predictions since many solar scientists believe that the best predictor of future solar cycle strength involves activity at the sun’s poles during a solar minimum phase. We should realize this occurrence is now rapidly approaching.

The monitoring of cosmic rays by spaceweather.com is now going global. Recently, launch sites in three continents were used: North America, South America and in Europe above the Arctic Circle.  Launching balloons from so many places gives the ability to map out the distribution of cosmic rays around our planet.  Scientists will continue to monitor their findings over the next several months as solar cycle 24 heads towards the next solar minimum. For more information on this study visit the “Intercontinental Space Weather Balloon Network”.

James Kamis suggests “conflicting temperature trends” between oceans and the atmosphere dispel the “myth” of man-made global warming. What it comes down to, he says our atmospheric temperature has remained static for more than 18 years, the Atlantic has got colder, and it is only the Pacific Ocean where things have heated up. Kamis said: “Scientists from the National Oceanic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration (NASA), and many universities are at a loss to explain recent conflicting temperature trends from Earth’s oceans and atmosphere.”

Look for a cold-snap sometime in the neighborhood of 2019-2020, because of lack of sunspots. It’s gonna happen, despite any of the crazy beliefs of “Global Warming.”


Kevin Roeten can be reached at roetenks@CHARTER.NET.

© Copyright by Kevin Roeten, 2017. All rights reserved.

Kevin Roeten
About Kevin Roeten 168 Articles
CHO's science editor Kevin Roeten is a former Chemical Engineer. He enjoys riding the third rail of journalism: politics and religion. As an orthodox Catholic, Roeten appreciates the juxtaposition of the two supposedly incompatible subjects.   Kevin is a Guest Columnist for the Asheville Citizen-Times, and the Independent (Ohio), and writes for numerous blogs (Nolan Chart, Allvoices) and newspapers, including USA Today.   A collaborator in the book Americans on Politics, Policy, and Pop Culture (Jason Wright and Aaron Lee), he is also an amateur astronomer, and delves into scientific topics.   Kevin Roeten can be reached at roetenks@charter.net.

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