The sun is very variable and even minor changes have a strong impact on the climate. The IPCC claims that changes in the sun have little impact on the climate. However, the data over the past 11,000 years, the Holocene, show that climate changes synchronized with solar cycles.

The Spanish scientist Javier Vinós has on the blog of the Climatologist Judith Curry (Book “Climate Uncertainty and Risk”) shown how the earth’s climate has changed considerably by a few degrees over the 2500 years “Bray-Zyklius”. These relationships are denied by the protagonists of climate change caused by “man-made CO2”.

How do you know what the temperatures were like in the past? To study the climate of the past, scientists use various climate proxy parameters that they collect in different parts of the world. In a large study published in Science magazine, 73 of these proxies were used to reconstruct the climate of the Holocene. Marcott, S.A., et al., 2013.A reconstruction of regional and global temperature for the past 11,300 years (A reconstruction of regional and global temperature in the past 11,300 years).

The results, which are also supported by a large number of other studies, show warm periods of thousands of years, which are referred to as climate optimum, followed by long cooling periods, which are referred to as neo-glacial.

Another study on the development of glaciers on Earth in the past 11,000 years has confirmed that this reconstruction is correct: Solomina, O.N., et al., 2015. Holocene glacier fluctuations (Holocene glacier fluctuations).

Because glaciers grow when it is colder and the results can be compared to temperature reconstruction. This shows a high degree of agreement. The glaciers confirm what the temperature reconstruction shows. In any case, the changes had nothing to do with „ man-made CO2.

Vinós shows these two graphics:

Note: The y-axis is the Z factor that relates to the temperature anomaly.

Both diagrams also show some strong cooling episodes that were associated with increased glacier growth. These abrupt climate events of the past have been examined and identified by paleoclimatologists. We will focus on four of the most important of them. The Boreal Oscillation, the 5.2-kilometer event, the 2.8-kilometer event, and the Little Ice Age.

The four are separated by a multiple of 2,500 years and form a cycle that I call the Bray cycle because this is the name of the scientist who discovered it in 1968: Bray, J.R., 1968. Glaciation and solar activity since the Fifth Century BC and the solar cycle (Cleasing and solar activity since the fifth century BC and the solar cycle) Nature.

Determination of solar activity in the Holocene

The sunspots are a measure of solar activity. If there is a larger number, a little more energy hits the earth, it is less so the total radiation is reduced. At the same time, the huge solar magnetic field changes. And this shields high-energy cosmic radiation from the earth when it is strong. If there are fewer sunspots and thus a weaker magnetic field, more radiation comes through. The isotope Be-10 (Beryllium-10) is formed, which otherwise does not occur on Earth. There are also collisions with nitrogen, which results in C14, the radioactive isotope of carbon.

Both Be-10 and C-14 are stored in the growth rings of trees and thus enable age determination.

Back to Vinós:

If we analyze the radiocarbon curve of the past 11,000 years, we find large deviations that indicate long periods of low solar activity. These extended periods of low solar activity are known as large solar minima and increase carbon 14 production by 2 %. The most common last about 75 years, and there have been about twenty of them in the past 11,000 years. The last was the Maunder minimum in the late 17th. Century. But there are also other types of large sun minima that are much more serious because they last twice as long, about 150 years. The last of these heavy sun minima was the Spörer minimum, which took place on the 15th and 16th. Century occurred.

There were only four such large minima of the Spörer type in the entire Holocene. The Homer minimum existed 2,800 years ago, 5,200 years ago the Sumerian minimum, and 10,300 years ago the Boreal minimum. We know when they came up thanks to the tree rings.

This shows us the connection between climate and solar activity. “If we count the number of sunspots in each solar cycle of the past 300 years and divide by the length of each cycle, we can see how much solar activity has deviated from the average. Since the Maunder minimum during the Little Ice Age, solar activity has increased and was well above average between 1933 and 1996, a period of six cycles of increased solar activity, which is the sun’s maximum of the 20th”.

Warming in the 20th. Century caused by increased solar activity. However, warmer oceans also result in the outgassing of CO2 and thus higher proportions of carbon dioxide in the air.

For the future, several astrophysicists predict a reduction in solar activity, but Vinós does not assume any change.

https://tkp.at/2024/04/26/daten-zeigen-klimawandel-haengt-von-der-sonne-ab/