Question: What is believed to have caused the Little Ice Age phenomenon in the Middle Ages?
About the article "Astronomy", section "Solar astronomy".

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Solar astronomy.
At a distance of about eight light-minutes, the most frequently studied star is the Sun, a typical main-sequence dwarf star of stellar class G2 V, and about 4.6 billion years (Gyr) old.
The Sun is not considered a variable star, but it does undergo periodic changes in activity known as the sunspot cycle.
This is an 11-year fluctuation in sunspot numbers.
Sunspots are regions of lower-than- average temperatures that are associated with intense magnetic activity.
The Sun has steadily increased in luminosity over the course of its life, increasing by 40% since it first became a main-sequence star.
The Sun has also undergone periodic changes in luminosity that can have a significant impact on the Earth.
The Maunder minimum, for example, is believed to have caused the Little Ice Age phenomenon during the Middle Ages.
The visible outer surface of the Sun is called the photosphere.
Above this layer is a thin region known as the chromosphere.
This is surrounded by a transition region of rapidly increasing temperatures, and finally by the super-heated corona.
At the center of the Sun is the core region, a volume of sufficient temperature and pressure for nuclear fusion to occur.
Above the core is the radiation zone, where the plasma conveys the energy flux by means of radiation.
Above that are the outer layers that form a convection zone where the gas material transports energy primarily through physical displacement of the gas.
It is believed that this convection zone creates the magnetic activity that generates sun spots.
A solar wind of plasma particles constantly streams outward from the Sun until, at the outermost limit of the solar system, it reaches the heliopause.
This solar wind interacts with the magnetosphere of the Earth to create the Van Allen radiation belts about the Earth, as well as the aurora where the lines of the Earth's magnetic field descend into the atmosphere.
Icecap climates have only existed in ice ages.
There have been at least five such ice ages in the Earth's past.
Outside these ages, the Earth seems to have been ice-free even in high latitudes.
By the geologic definition, Earth is currently in an ice age, in that the planet has permanent ice caps.
Factors that cause ice ages include changes to the atmosphere, the arrangement of continents, the energy received from the sun, volcanos, and meteor impacts.
The current era is believed to be the only time in the last 600 million years of Earth's history with ice caps at both poles.
The Antarctic ice cap was formed after Antarctica split from South America, allowing the formation of the Antarctic Circumpolar Current.
The Arctic ice cap was partially caused by the Azolla event, where a large number of ferns in the ocean died, sank, and never decayed, which trapped carbon dioxide beneath the ocean.
There is a hypothesis that around 650 million years ago, the entire planet was frozen, called Snowball Earth.
Essentially the entire planet had an ice cap climate.
However, this theory is disputed, and even proponents suggest there was an area of periodic melting near the equator. 
Some public health researchers have argued that the Hispanic paradox is not actually a national phenomenon in the United States.
In 2006, Smith and Bradshaw argued that no Hispanic paradox exists.
They maintain that life expectancies were nearly equal for non-Hispanic White and Hispanic females, but less close for non-Hispanic White and Hispanic Males.
Turra and Goldman argue that the paradox is concentrated among the foreign born from specific national origins, and is only present in those of middle to older ages.
At younger ages, they explain, deaths are highly related to environmental factors such as homicides and accidents.
Deaths at older ages, they maintain, are more related to detrimental health-related behaviors and health status at younger ages.
Therefore, immigration-related processes only offer survival protection to those at middle and older ages; the negative impact of assimilation into poor neighborhoods is higher on the mortality of immigrants at a younger age.
In contrast, Palloni and Arias hypothesize that this phenomenon is most likely caused by across-the-board bias in underestimating mortality rates, caused by ethnic misidentification or an overstatement of ages.
These errors could also be related to mistakes in matching death records to the National Health Interview Survey, missing security numbers, or complex surnames. 
Since the discovery of the Little Ice Age, there have been doubts about whether it was a global phenomenon or a cold spell restricted to the Northern Hemisphere.
In recent years, several scientific works have pointed out the existence of cold spells and climate changes in areas of the Southern Hemisphere and their correlation to the Little Ice Age. 
The famine occurred in a period known as the Little Ice Age.
During the 1690s, climate in Europe was characterised by cold springs and summers.
It is generally estimated that temperatures were 1.5oC lower during the 1690s than the average during the Little Ice Age.
This impacted other countries, France suffered the worst famine since the Middle Ages, ice floes formed in the Thames while Lake Constance and Lake Zurich froze completely over.