by Javier Vinos
Part I of the series consists of three parts.
The sun is a variable star and the amount of energy it emits varies from month to month, year to year and century to century. One of the manifestations of these variations is sunspots, which are more common when the Sun is more active and disappear when the Sun is less active. These sunspots follow a solar cycle of about 11 years, but sometimes there is a longer period, decades or centuries, when solar activity is so low that no sunspots remain. These periods are called great solar minimums. There are also periods of decades or centuries of higher activity. These are called great solar maxima.
The sun provides 99.9% of the energy the climate system receives. Therefore, there are always scientists who believe that changes in the Sun are the cause of climate change. The problem is they never had enough evidence to prove it. Until now.
- The IPCC and NASA said…
The IPCC and NASA believe that the Sun’s changes have little effect on climate. They rely on two arguments. The first is that changes in solar activity are very small. We measure them with satellites because they cannot be measured from the surface, and we know that the radiant energy coming from the Sun only changes by 0.1%. The magnitude of the changes is better appreciated when we use the full scale. Many scientists believe that such a small change could only create small changes in climate.
The second argument is that the development of temperature does not coincide with the development of solar activity. Since the 1990s, solar activity has decreased while warming has continued.[i]
Actually, this argument is not valid because it does not say that the Sun does not affect temperature, but it is not the only factor that does so, which we already know because temperature reacts to many factors such as El Niño, volcanoes, polar vortex, or changes in Earth’s orbit. There are many natural causes of climate change and what we need to know is whether the Sun is one of the main causes.
To find out, we don’t need to care what the IPCC and NASA think, we need to ask the climate itself. No matter how small the changes in the Sun are, it doesn’t matter if the climate reacts strongly to them by causing large changes.
- Climate during the Holocene
And the best way to find out is to look at what happened to the climate over the past 11,000 years, the interglacial period we call the Holocene. The advantage of this is that Holocene climate changes cannot be caused by changes in CO₂. They must be caused by something else.
To study past climate, scientists use many different climate parameters that they collect in many places around the world. A large study published in Science used 73 of these proxies to reconstruct the Holocene climate.[ii] I used the same proxies, with a slight modification in how they were combined.
What we see, and what many studies also support, is that there was a period of warmth lasting thousands of years, called the Climatic Optimum, followed by a period of prolonged cooling. long period, called the New Ice Age.
How do we know that this reconstruction is accurate? Another study reconstructed the formation of glaciers on Earth over the past 11,000 years.[iii] They divided the globe into 17 regions, and this chart shows the number of regions with glaciers increasing in size during each century of the Holocene.
Since glaciers grow when it gets colder, we can invert their shape and compare it to a temperature reconstruction chart so that the meaning is the same. We found a high level of agreement. The glaciers confirm what the temperature reconstruction shows. We also know that CO₂ did the opposite to temperature, but that’s a story for another day.
Note: the y axis is the Z coefficient, related to temperature anomalies.
Both graphs also show several periods of severe cooling associated with increased glacier growth. These sudden climatic events in the past have been studied and identified by paleoclimatologists. Among them, we will focus on the four most important ones. Northern Oscillation, 5.2 kiloyear event, 2.8 kiloyear event and Little Ice Age.
These four cycles are separated by multiples of 2,500 years and form a cycle that I call the Bray cycle because that is the name of the scientist who discovered it in 1968.[iv]
Now that we know past climate, we need to talk about past solar activity.
- Past solar activity
Solar activity is recorded in tree rings through the impact of cosmic rays. A continuous stream of cosmic rays from the galaxy to the solar system. Some interact with the atmosphere. Some collide with atmospheric nitrogen, converting it to carbon-14, which is heavier than regular carbon-12 and radioactive. This carbon-14 combines with oxygen to form radioactive CO₂, which is breathed by plants. Carbon is used during photosynthesis to create cellulose, which helps plant stems grow in diameter. When a tree dies, the carbon-14 in the wood gradually decomposes over centuries and millennia. You only need to measure the amount of carbon-14 remaining in the wood to know how much time has passed since the tree died.
Each tree’s growth ring records how much carbon-14 was in the atmosphere that year, and scientists used thousand-year-old trees and preserved logs to construct a calibration curve that spans decades. thousand years. This allows them to determine the age of any organic remains, even if it is not a tree trunk, simply by knowing how much carbon-14 is in it. This is called radiocarbon dating.
The only problem is that the production of carbon-14 by cosmic rays is intermittent. The Sun’s magnetic field deflects the paths of cosmic rays, causing many to deviate from Earth, and changes in the Sun’s activity affect its magnetic field.
As solar activity increases, fewer cosmic rays arrive, less carbon-14 is produced, and organic remains appear older because they contain less carbon-14. As solar activity becomes weaker, more cosmic rays arrive, more carbon-14 is produced, and organic matter looks younger because it contains more carbon-14.
This creates deviations in the standard curve that allow us to know what the Sun’s activity was in the past.
- Spörer-type solar minimum
When we analyze the radiocarbon curve over the past 11,000 years, we observe large deviations that indicate long periods of low solar activity. These extended periods of low solar activity are called major solar minimums and increase carbon-14 output by 2%. The most common ones have been around for about 75 years, and there have been about 20 in the last 11,000 years. The most recent was the Maunder Minimal at the end of the 17th century. But there are other types of major solar minima that are much more serious because they last twice as long, about 150 years. The last extreme solar minimum was the Spörer Minimum, which occurred in the 15th and 16th centuries.
There are only four such Spörer-type large minima in the entire Holocene. 2,800 years ago, there was the Homer Minimum, 5,200 years ago the Sumerian Minimum and 10,300 years ago the Northern Minimum. We know when they occur thanks to tree rings.
If the dates sound familiar, it’s because the four Spörer-type Holocene minima coincide exactly with the four major climate events on the chart we saw earlier. We know that during each of these great solar minimums, when solar activity decreased for 150 years, the climate experienced a tremendous cooling that greatly affected climate factors worldwide. bridge.
We also know that low solar activity during the Great Minimum had a major impact on human populations. Previous human settlements and their component structures can be radiocarbon dated. In the past, when people lived well, the population increased and they built more, and when they lived poorly, usually because there was less food, the population decreased and they built less. Scientists have estimated the evolution of the human population in the British Isles by analyzing radiocarbon dates of thousands of remains from hundreds of archaeological excavations.[v]
What they discovered was that population increased greatly with the advent of agriculture, but every time the climate seriously deteriorated, the human population suffered from ever-diminishing resources. And the largest drop occurs when the large Spörer-type solar minimum occurs. Other population declines have also coincided with other cooling periods, confirming our rebuilding process.
This tells us that the worst climate changes in the past were caused by changes in solar activity. It also tells us that what is harmful to humanity is cooling, not warming.
Now we can respond to the IPCC and NASA. Never mind that solar radiation varies very little, and never mind that temperature is not always the same as solar activity. Clearly there are other factors at play. But we can say unequivocally that changes in solar activity affect climate because climate speaks for itself. The study of past climates leaves no room for doubt. The sun changes the climate. And if we don’t know how it works then we should study it.
- 20th century solar maximum
Since low solar activity causes cooling, it stands to reason that high activity would cause warming. Solar activity during the 20th century was very high, in the top 10% over the past 11,000 years.
If we count the number of sunspots in each solar cycle over 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 much higher than average between 1933 and 1996, a period of six cycles of activity. The rising sun formed the 20th century solar maximum.
Although we cannot know how much of the 20th century’s warming was caused by this modern solar maximum, there is no denying that it was an important part, because as we have seen, The sun is the cause of most climate change in recent times. The past 11,000 years.
- Conclude
There are two good news. The first is that solar activity cannot exceed the 20th century maximum. It is unlike CO₂, which can continue to increase. Solar activity can remain high or decrease but cannot increase, so warming will not accelerate and pose no danger.
In 2016, I developed a model to predict solar activity in the 21st century. At the time, some scientists believed that solar activity would continue to decline until a new century occurred. minor glaciation and new major minimum. But my model predicts that solar activity in the 21st century will be similar to the 20th century. It is also predicted that the current solar cycle, the 25th, will be more active than the previous cycle , and that was right.
The second good news is that if most of the 20th century warming was due to the Sun, there would be no climate emergency. Believing that all climate change is due to our emissions is one of the errors that sometimes occurs in science, as is believing that the Earth is the center of the solar system, that space is interstellar. Ether-filled semen or stomach ulcers are caused by stress. , not bacteria.
This article can also
[i] NASA. Does the sun cause global warming?
[ii] Marcot, S.A. et al., 2013. Reproduction of regional and global temperatures over the past 11,300 years. science, 339 (6124), pp. 1198-1201.
[iii] Solomina, ON et al., 2015. Holocene glacier fluctuations. Quaternary scientific comments, 111page 9-34.
[iv] Bray, J.R., 1968. Glaciation and solar activity since the fifth century BC and the solar cycle. Nature, 220 (5168).
[v] Bevan, A., et al., 2017. Holocene fluctuations in human populations demonstrate recurring links with food production and climate. PNAS, 114 (49), pp. E10524-E10531.
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