The above chart suggests the question: “Do sunspots provide us information that can help us ascertain the Sun’s changes that alter the Earth’s climate?”. In the above chart at the right, we see a decline, as if there were an emerging Grand Solar Minimum, which happened in cooler times in the past, such as the Maunder Minimum above. Some scientists have found a basis for the sunspot number in magnetic field cycles, and research and verification in this area is underway.
But presently there is a concern that the Sun’s activity, as measured by sunspots, affects the Earth considerably.
“While the Sun provides for us, it is also capable of taking away. The weather and climatic scales of solar evolution and the Sun-Earth connection are not well understood.”
There are three principle ideas here: the first is that a decline in solar activity reduces total irradiance on the Earth, which is found to have a minor correlation. The second and of more significance is that a decline in solar activity reduces ultraviolet photon radiation, which are the highest energy photons, and this could affect temperature changes on Earth.
Third, and perhaps the most influential, is that reduced solar activity, demonstrated by fewer sunspots, also correlates with less solar flares that reach the Earth. Since the solar flares shield the planet from cosmic radiation (coming from the Milky Way and other parts of the universe), which is significant, and these cosmic rays ionize water molecules, making them attract one another, we can infer that with fewer sunspots there will be more cloud cover. More cloud cover causes more reflection of solar radiation, cooling the Earth, and more clouds produce more precipitation.
1 High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO, USA
2 Department of Physics, Montana State University, Bozeman, MT, USA
The charts below explain the present concern. Sunspot activity has been recorded accurately since the 17th century, as the top chart shows. The temperature plot on the lower left (aligned on year with the top chart) shows anomalies, or variations from a mean, and shows a clear correlation with solar activity and temperatures. This data correspondence, along with the causal understanding above, has motivated scientists at NASA, in Belgium and elsewhere to try and predict future sunspot activity.
If sunspot activity decreases, will temperatures on Earth decline? That is the question.
There is a clear correspondence shown by the green arrows on the right, above, when sunspot numbers have increased, temperatures on Earth have increased. If sunspot numbers now decline, as expected, and if temperatures decline, then there will be a causally correlated confirmation.
NASA has confirmed that:
“The forecast for the next solar cycle says it will be the weakest of the last 200 years. The maximum of this next cycle – measured in terms of sunspot number, a standard measure of solar activity level – could be 30 to 50% lower than the most recent one. The results show that the next cycle will start in 2020 and reach its maximum in 2025.”