On Friday, January 12, 2018 at 6:31:11 PM UTC-7, RichA wrote:

(Phys.org)—Is Earth slowly heading for a new ice age? Looking at the
decreasing number of sunspots, it may seem that we are entering a nearly
spotless solar cycle which could result in lower temperatures for decades..
"The solar cycle is starting to decline. Now we have less active regions
visible on the sun's disk," Yaireska M. Collado-Vega, a space weather
forecaster at NASA's Goddard Space Flight Center, told Phys.org.

But does it really mean a colder climate for our planet in the near future?
In 1645, the so-called Maunder Minimum period started, when there were
almost no sunspots. It lasted for 70 years and coincided with the well-
known "Little Ice Age", when Europe and North America experienced lower-
than-average temperatures. However, the theory that decreased solar activity
caused the climate change is still controversial as no convincing evidence
has been shown to prove this correlation.

Particularly since sunspots are areas of the sun that are COOLER than the
bright parts. Simplistic argument would say that fewer sunspots should
lead to WARMER weather on earth, but the reverse seems to be true.

The connection may be coming clearer, though. Sunspots are responsible
for the solar wind, which increases with sunspot activity and decreases
with reduced activity. It appears that the solar wind deflects cosmic
rays, so more cosmic rays impact earth during periods of low solar
activity:

https://www.vencoreweather.com/blog/...s-next-minimum

The CLOUD project has linked nucleation of clouds to cosmic rays (which are
actually mostly very high energy protons):

http://cloud.web.cern.ch/cloud

So that's the connection: lower solar activity may cause increased cloud
cover, increasing earth's albedo and reflecting more sunlight back into
space.

Helen Popova, a Lomonosov Moscow State University researcher predicts that
if the existing theories about the impact of solar activity on the climate
are true, then this minimum will lead to a significant cooling, similar to
the one during the Maunder Minimum period. She recently developed a unique
physical-mathematical model of the evolution of the magnetic activity of
the sun and used it to gain the patterns of occurrence of global minima of
solar activity and gave them a physical interpretation.

"Given that our future minimum will last for at least three solar cycles,
which is about 30 years, it is possible that the lowering of the temperature
will not be as deep as during the Maunder Minimum," Popova said earlier in
July. "But we will have to examine it in detail. We keep in touch with
climatologists from different countries. We plan to work in this direction."

There was the Dalton minimum that occurred around 1810 for a few years each
way:

https://en.wikipedia.org/wiki/Dalton_Minimum

which coincided with the "year without a summer" in 1816 wherein global
temperatures dropped about 0.5 degrees C. That drop, however, occurred at
the same time that Mt. Tambora blew its top (1815) and ejected about 10
cubic miles of itself into the air, much of which was fine ash that stayed
in the atmosphere for many months.

The Maunder minimum was also associated with excessive volcanic activity,
so it's difficult to separate whether that or sunspots (or some other effects that have been hypothesized) were to blame for the reduced global temperature.
Since we are approaching a period of extremely low solar activity:

http://www.sidc.be/silso/dayssnplot

it will be interesting to see what happens. Also, the length of time of
this lowered activity is likely significant. If lack of sunspots had
anything to do with the Maunder minimum, the inactive period was QUITE
long, approximately 50 years, and so was the period of the Little Ice Age:

https://en.wikipedia.org/wiki/Little_Ice_Age

The Dalton minimum was a much shorter period.

One thing is certain, though: Climate models have NOT taken these phenomena
into account. Consequently, there must be some doubt in their ability to
give accurate predictions and more than a little doubt in those who have
loudly proclaimed that the science is settled.

“There are more things in heaven and earth, Horatio, than are dreamt
of in your philosophy.” -- Shakespeare