- A new 11-year-cycle of the Sun has begun.
- Scientists believe the Sun was at its weakest in 2019 in the last 100 years or so — known as the solar minimum — and 2020 marks the beginning of the 25th cycle.
- But the odd thing is that solar activity, measured by the number of Sun spots at any given time, is pretty low even in 2020.
- Sun spots are areas of strong magnetic forces on the surface of the Sun — sometimes as large as planets — that appear as darker spots because they are cooler.
- The Sun had no Sun spots for around 71 per cent in 2020 through September 21, 2020, compared to 77 per cent in 2019.
- Scientists say the Sun may be going through a long period of decreased activity known as the Modern Grand Solar Minimum from 2020 to 2053.
- The last time such an event occurred was during the Maunder Minimum — from 1645 AD to 1710 AD, which was part of what is now known as the Little Ice Age — when Earth went through a series of elongated cold periods during the medieval centuries.
- S study predicted that the surface temperatures on Earth will go down noticeably during the Modern Grand Solar Minimum due to a 70 per cent reduction in solar magnetic activity.
- Variations in solar irradiance lead to heating of the upper layer of the Earth’s atmosphere and influences the transport of solar energy towards the planet’s surface.
- The magnetic activity through the solar background magnetic field which occurs in the form of two magnetic waves inside the Sun.
- Combined these two waves for solar cycles 21-26, found that the Sun’s magnitude is going down in cycles 24-25 and becoming almost zero in cycle 26.
- Also found multiple grand solar minima events, including the current event from 2020-2053.
- During the Maunder Minimum in the middle ages, the solar irradiance went down by 0.22 per cent or 3 watt per square metre (W/sqm) in 1710 AD when the period ended.
- This brought down the temperatures in the Northern Hemisphere, especially in Europe, by 1-1.5 degree Celsius and led to frozen rivers, long cold winters and cold summers.
- This happened because of the complex impacts of decreased solar activity on the abundance of ozone in the Earth’s atmosphere and on climatic cycles such as the North Atlantic Oscillation (NAO).
- The NAO, the balance between a permanent low-pressure system near Greenland and a permanent high-pressure system to its south, was in a negative phase during the Maunder Minimum. This plunged Europe into colder-than usual temperatures.
- There is another reason for the cooling, directly related to the sun’s magnetic field, which shields the Earth from harmful cosmic and galactic rays.
- In the absence of the shielding more rays reaching the Earth and forming high clouds in the atmosphere, it is leading to the cooling.
- The planet’s temperature might plummet by 1°C during the current grand solar minimum.
- The possible decrease in temperatures has led to people, even some scientists, to predict that the solar minimum cooling might cause a Little Ice Age and offset the rising temperatures due to global warming.
- But the National Aeronautics and Space Administration (NASA) is not very sure about such a conclusion.
- In February 2020, it released a statement that dispelled the fact that there would be any major effect on global temperature rise due to greenhouse gas emissions due to human activities.
- It said even during a Grand Solar Minimum, the decrease in climate forcing would only be worth as much as three years of carbon dioxide growth in the atmosphere.
- NASA also said the impact of global warming would be six times greater than the cooling caused by the Grand Solar Minimum, and that even if the period lasted for a century, the planet would continue to warm.
