Originally published September 2, 2020
In a new study published recently in the journal Temperature, Prof. Valentina Zharkova demonstrates that the Sun has entered into the modern Grand Solar Minimum (2020 - 2053) that will lead to a significant reduction of the solar magnetic field and activity like during Maunder minimum leading to a noticeable reduction of terrestrial temperature.
- This can have important implications for different parts of the planet on growing vegetation, agriculture, food supplies, and heating needs in both the northern and southern hemispheres during the next 30 years.
- This global cooling during the upcoming grand solar minimum can offset for three decades any signs of global warming and would require inter-government efforts to tackle problems with heat and food supplies for the whole population of the Earth.
"Sun is the main source of energy for all planets of the solar system," Prof. Zharkova states. "This energy is delivered to Earth in a form of solar radiation in different wavelengths, called total solar irradiance. Variations of solar irradiance lead to heating of upper planetary atmosphere and complex processes of solar energy transport toward a planetary surface."
Zharkova demonstrates that recent progress with the understanding of the role of solar background magnetic field in defining solar activity and with quantifying the observed magnitudes of the magnetic field at different times enabled reliable long-term prediction of solar activity on a millennium timescale.
This approach revealed the presence of not only 11-year solar cycles but also of grand solar cycles with a duration of 350 - 400 years.
"These grand cycles are formed by the interferences of two magnetic waves with close but not equal frequencies produced by the double solar dynamo action at different depths of the solar interior. These grand cycles are always separated by grand solar minima of Maunder minimum type, which regularly occurred in the past forming well-known Maunder, Wolf, Oort, Homeric, and other grand minima," Zharkova noted.
"During these grand solar minima, there is a significant reduction of the solar magnetic field and solar irradiance, which impose the reduction of terrestrial temperatures derived for these periods from the analysis of terrestrial biomass during the past 12 000 or more years."
(Figure 1) Top plot: two principal components (PCs) of solar background magnetic field (blue and green curves, arbitrary numbers) obtained for cycles 21 - 23 (historic data) and predicted for cycles 24 - 26 using the mathematical formulae derived from the historical data. The bottom plot: The summary curve derived from the two PCs above for the “historical” data (cycles 21 - 23) and predicted for solar cycle 24 (2008 - 2019), cycle 25 (2020 - 2031), cycle 26 (2031 - 2042).
(Figure 3) Solar activity (summary) curve restored for 1200 - 3300 AD.
The most recent grand solar minimum occurred during the Maunder Minimum -- which lasted 65 years, from 1645 to 1710.
During this period, the temperatures across much of the northern hemisphere plunged. This likely occurred because the total solar irradiance was reduced by 0.22% that led to a decrease of the average terrestrial temperature measured mainly in the northern hemisphere in Europe by 1.0 – 1.5 °C (1.8 - 2.7 °F). This seemingly small decrease in the average temperature in the northern hemisphere led to frozen rivers, cold long winters, and cold summers.
"The discovery of double dynamo action in the Sun brought us a timely warning about the upcoming grand solar minimum when solar magnetic field and its magnetic activity will be reduced by 70%."
Zharkova states that this period has started in the Sun in 2020 and expects it to last until 2053.
During this modern grand minimum, one would expect to see a reduction of the average terrestrial temperature by up to 1.0 °C (1.8 °F), especially, during the periods of solar minima between the cycles 25 - 26 and 26 - 27, e.g. in the decade 2031 - 2043.
(Figure 2) Top plot: The modulus summary curve (black curve) obtained from the summary curve (Figure 1, bottom plot) versus the averaged sunspot numbers (red curve) for the historical data (cycles 21 - 23). Bottom plot: The modulus summary curve associated with the sunspot numbers derived for cycles 21 - 23 (and calculated for cycles 24 - 26).
"The reduction of a terrestrial temperature during the next 30 years can have important implications for different parts of the planet on growing vegetation, agriculture, food supplies, and heating needs in both northern and southern hemispheres. This global cooling during the upcoming grand solar minimum (2020–2053) can offset for three decades any signs of global warming and would require inter-government efforts to tackle problems with heat and food supplies for the whole population of the Earth."
"Modern Grand Solar Minimum will lead to terrestrial cooling" - Valentina Zharkova (2020) - Temperature - DOI: 10.1080/23328940.2020.1796243 - OPEN ACCESS
Featured image: Sunset over Phoenix, Arizona. Credit: Alexander Nie