The sun is both the main source of life and the greatest threat to it. On the one hand, the star converts four million tons of matter every second into energy, which is the main source of light and heat. On the other hand, it is a source of powerful emissions that cause strong disturbances on Earth and near-earth space.
Magnetic storms and auroras are nothing more than a consequence of anomalies occurring on the luminary. Fortunately, today scientists have learned to predict these manifestations, and humanity as a whole already knows how to neutralize their negative impact.
At the same time, some of the processes occurring on the Sun cause concern among specialists. Experts around the world state an unprecedented decrease in solar activity and predict the approach of a new ice age – the fifth in the last 400 thousand years.
What are solar cycles
A lot of what happens on the Sun and, as a consequence, in the entire solar system, depends on the state of the magnetic field of the star. Its amplitude and spatial configuration are constantly changing, which, together with the formation and decay of other strong fields in the atmosphere, leads to the transformation of the wave radiation of a celestial object and the intensity of fluxes of corpuscles – particles of solar gas in a plasma state. The number of spots – relatively cold regions in its photosphere – on the surface of the Sun also changes.
Long-term studies have shown that the activity of a star associated with the appearance of spots has a cyclic structure. Scientists estimate the duration of the cycles in different ways – up to six thousand years, but most often they distinguish three periods: 11-year, 90-year and 300-400-year cycles.
The shortest of them is more pronounced and is associated with changes in the direction of the main component of the magnetic field of the star. The period is characterized by a rather rapid – for about four years – increase in the number of sunspots and its subsequent decrease, which takes about seven years. At the same time, the assessment of the cycle duration of 11 years is an average, in some cases it can last from nine to 14 years.
The 90-year variation is associated with a 25-50 percent periodic decrease in the number of sunspots in 11-year cycles. 300-400-year intervals are completely characterized by the appearance of long, up to several tens of years, intervals when very few sunspots appear on the Sun. The last such period was recorded quite recently – in 2017. And the most famous – the Maunder minimum – lasted from about 1645 to 1715 and coincided in time with the coldest phase of climate cooling – the Little Ice Age.
How the Sun’s cycling affects the Earth
Scientists have long formed certain ideas that the activity of a star affects the climate – both space and terrestrial. When there are many sunspots on the Sun, the probability of reconnection of magnetic lines of different polarities increases. The visible result of this process is flares, characterized by explosive energy release. This burst of radiation, reaching the Earth, causes strong disturbances in its magnetic field, disrupts satellites and increases the likelihood of aurora borealis in low geographic latitudes.
The planet’s ionosphere is also subject to fluctuations in solar activity, which manifests itself in a change in the propagation of short radio waves. It also affects the chemical processes in the Earth’s atmosphere, since it affects the intensity of galactic cosmic ray fluxes.
Moreover, it is now known that a change in the total value of the electromagnetic radiation of the Sun by only one percent can entail a noticeable change in the distribution of temperature and air currents on the Earth. An increase in the flow of particles leads to the fact that warm currents from the south rush with even greater energy to the northern latitudes, and the cold ones, carrying the Arctic air, penetrate deeper to the south.
Should we wait for a new ice age?
Each solar minimum traditionally raises concerns about the possible onset of the next global cooling, akin to that observed at the turn of the 17th and 18th centuries. During the Little Ice Age, global average temperatures dropped by one to two degrees Celsius, snow lay on some of the plains all year round, and Greenland was covered with glaciers. Moreover, the waters of the Thames and Danube rivers were frozen, and the Moscow River was covered with ice every six months.
However, for such cataclysms, a simple decrease in solar activity is not enough; a significant deviation is needed. A sharp decline, according to an international group of scientists, may occur in 2030-2040. This conclusion was made by experts after analyzing solar radiation during the 1982-2002 cycles. The data they obtained made it possible to derive analytical formulas that can be used to predict the behavior of a star in the period from 1200 to 3200.
“If the existing theories about the influence of solar activity on the climate are correct, then this minimum will lead to a significant cooling, similar to that which was during the Maunder minimum. In view of the fact that our future minimum will last three solar cycles – about 30 years, perhaps the decrease in temperature will not be as deep as in the Maunder minimum. But this will need to be studied in more detail, ”the MSU website writes.
Scientists see a lot of other “bells” that foreshadow a sharp decline in solar activity. For example, Matthew Penn, an astronomer at the National Solar Observatory in Tucson, Arizona, told Deutsche Welle that sunspots are not observed at all if the magnetic field of the star falls below 1500 gauss. Moreover, in the penultimate cycle, local fields weakened by about 50 gauss per year.
“If we extrapolate this trend, then by 2021 they will become too weak and will not be able to resist convection. The spots on the Sun will disappear,” he stated.
The director of the National Solar Observatory in Tucson, Frank Hill, even notes that in the new millennium, a malfunction was recorded in the formation of a plasma flow, the movement of which to the equator of the star and becomes the cause of the appearance of spots.
At the same time, the connection between disruptions in solar activity and the beginning of ice ages has not yet been reliably established, and so far experts are very cautious about this.
“My position is this: we do not yet have scientific data that could confirm or deny such a relationship,” Frank Hill emphasized. – Of course, a long minimum of solar activity, in principle, will have some effect on everything – both on space exploration and on the Earth’s climate. But I still want to emphasize: we are predicting changes in the solar cycle, and not at all the onset of a new Little Ice Age.”