BLOG 60 Climate Cycles and Climate Change by Award-winning Author, Adventurer and Scientist Mark K. Levin PhD
How much change has Earth’s climate had in the past 1000, 100,000, and 600 million years?
Figure 1. Milutin Milankovitch was born May 28, 1879, in Dalj, Austria-Hungary, which is now in Croatia. He died December 12, 1958, in Belgrade, Yugoslavia, which is now in Serbia. Credit Wikipedia
Milutin Milankovitch was a Serbian astrophysicist and mathematician. He is best known for developing one of the most significant theories explaining the ice ages and other factors relating Earth motions and long-term climate cycles, which many refer to as climate change.
Milankovitch dedicated his career to developing a mathematical theory of Earth’s climate. Below is a quote from Steve Graham published by NASA March 24, 2000:
“Milankovitch dedicated his career to developing a mathematical theory of climate based on the seasonal and latitudinal variations of solar radiation received by the Earth. Now known as the Milankovitch Theory, it states that as the Earth travels through space around the sun, cyclical variations in three elements of Earth-sun geometry combine to produce variations in the amount of solar energy that reaches Earth.
Variations in the Earth’s orbital eccentricity—the shape of the orbit around the sun.
Changes in obliquity—changes in the angle that Earth’s axis makes with the plane of Earth’s orbit.
Precession—the change in the direction of the Earth’s axis of rotation, i.e., the axis of rotation behaves like the spin axis of a top that is winding down; hence it traces a circle on the celestial sphere over a period of time.
Together, the periods of these orbital motions have become known as Milankovitch cycles.”
We know Earth was in an ice age about 10,000 to 15,000 years ago. We also know the ice age started about 115,000 years ago and lasted for about 100,000 years. Note that in the last ice age surface temperatures were higher and the oceans also higher than today, so we are in a climate cycle. Yes, we are in a warming part of this current cycle. The question is where will we peak and when? I do not know, but many oceanographers, geophysics, geologists and other research scientists are hypothesizing, and they do not all agree.
Our planet’s temperature has changed only about 0.7 degrees in the past hundred years and that seems very small to me. The accuracy of taking average temperatures of a room is usually about 0.8 degrees C. We are not really taking the average temperature, we are making big assumptions. First, taking the average temperature of the planet is not easy! At what altitudes should we take the temperature? At what time of day? At what depth in the ocean and how many different depths and how often?
Earth has experienced many climate cycles in the past and as we study these in greater detail, the data are beginning to support the Milankovitch hypothesis about change in Earth’s orbits. These changes are influenced by many orbital factors figured out by Milankovitch. He first set out his hypotheses in the 1920s. We know about past climates cycles because of evidence left such as air bubbles in ice, layers of ice in glaciers, ocean sediments, coral reefs, layers of sedimentary rocks and tree rings. For example, bubbles of air in glacial ice trap tiny samples of Earth’s atmosphere, giving scientists a history of greenhouse gases that goes back more than 800,000 years. The chemical make-up of the ice provides clues to the average global temperature. It is science, but it is not as accurate as we wish. There is room for doubt.
Yes, there is evidence that the rate of temperature change may be gaining steam. We need more time to really know for sure, but to be on the safe side we need to spend billions of dollars to find out. There are ways to cool the Earth using some simple geoengineering methods to make more clouds that will reflect the sun’s rays and cool the planet. If we do this before we know for sure we could be fighting an early ice age. If you look at the curve below, you will see the cycle of temperature as measured with CO2 trapped in ice:
Figure 2. “Glacial ice and air bubbles trapped in it (top) preserve an 800,000-year record of temperature & carbon dioxide. Earth has cycled between ice ages (low points, large negative anomalies) and warm interglacial (peaks). (Photograph courtesy National Snow & Ice Data Center. NASA graph by Robert Simmon, based on data from Jouzel et al., 2007.)”
When we reach the next peak, we can expect the temperature to drop rapidly, as you can see in the other cycles. Not in few days or a few years but in decades. What can we do now? We can fix the problem with geoengineering once we know for sure, so let us do what governments do— study the problem until we are on the other side of the peak. Wait and see is another way of saying it.
Lorraine Lisiecki published a paper that studied climate cycles over that past 1.2 million years using sediments. She is at UC Santa Barbara and she is a geologist who reported her work in the journal Nature Geoscience. She observed a pattern that connects the regular changes of Earth’s orbital cycles to changes in Earth’s climate supporting the Milankovitch theory.
The sun can be a big factor if the output changes. Some scientists tell us about variation in solar output, which they propose as a possible reason for our slight 0.7 degrees Celsius rise; others seem to think it is carbon dioxide from human use of fossil fuels causing the temperature increase. Time will tell.
Figure 3. Lorraine Lisiecki on the California coast near Santa Barbara. Credit University of CALIFORNIA at Santa Barbara
Lisiecki performed her analysis of climate by examining ocean sediment cores. These cores come from 57 locations around the world. By analyzing sediments, scientists are able to chart Earth’s climate for millions of years in the past. Lisiecki’s contribution is the linking of the climate record to the history of Earth’s orbits as we understand them. Why?
The basic hypotheses are that the climate is changed by the amount of solar energy striking Earth. Yes, there are other factor such as asteroid impacts, comet impacts, ocean circulation, atmospheric gases and volcanoes. If we look back in the past, we see the carbon dioxide following temperature.
Figure 4. Recent Carbon Dioxide vs. Temperature Data up to 1995. Earth temperatures are better correlated here than longer term as shown below in Figure 5 and 6.
Perhaps these are correlated, but which came first the change in temperature or the change in carbon dioxide (CO2)? I do not know, as the data is an approximation that is not accurate to a YEAR. Also what temperature are they using, surface or average? The orbits change slowly. CO2 can have a big effect, but what causes the CO2 levels to change? Could the sun heat the water so that CO2 comes out of the ocean, or does the CO2 come out and then the temperature rises? There is a controversy and science is open to new ideas and controversy. What can we do? The proponents of solar energy advocate to take the safer road as do many climatetologits.
There are arguments that the rate of change could be a real problem. Some see it and other do not. In 1905 only about 2 percent of scientists agreed with Einstein when he said the speed of light is the same whether you are traveling towards the light or are speeding away from it. Today we accept this as proven fact. Why? We are able to test and verify Einstein’s crazy idea. How can we verify where we are when will we change? Maybe if we hit the maximum within 20 to 40 years as we are near the top of the cycle, then we should have an idea by tests result of our start down into a new ice age. If the sun is dominant, then we should begin to drop. If not, then the carbon dioxide has a bigger role.
By the way, if temperatures drop in a few thousand years we could be into serious global cooling, and it will last for about 100,000 years. How can we soften this extreme when all of Canada and part of the USA will become covered with more than one mile of ice? Maybe burning fossil fuel to add CO2 will be a good thing then.
Figure 5. Orbit of Earth during the warm interglacial portion of the cycle.
Figure 6. Elliptical orbit during ice age portion of the climate cycle.
What is the graph of carbon dioxide since snowball Earth? About 600 million years ago, Earth’s surface was cold and covered with ice, even at the equator, including the ocean. Then the volcanoes emitted carbon dioxide and many other gases. Below we can see that after the freeze, we warmed up. Otherwise we might not be here now.
CO2 was over 18 times greater than TODAY, but Scripps reported 412.60 ppm on May 14, 2018 and reported 412.45 ppm on May 14, 2018. Carbon dioxide levels are low compared to the past if we look on the 600 million-year scale. Long-term the correlation is not there. In the last interglacial warm period, temperature went up and carbon dioxide went down. That is not correlated.
In conclusion, I would say we need to wait 50 to 100 years to see where we are going and how fast technically; however, for safety reasons perhaps we had better get started now. How much should we spend and where do we spend? That is a topic for another blog. The information we have is not scientifically adequate to say CO2 and temperature are correlated. Below are a few of my reasons. Most scientists only track CO2 for a few hundred thousand years and not billions. Earth is 4.5 billion years old.
In my opinion, the correlation is very bad, which can be seen easily by looking at the above graph! High CO2 concentrations between 200 and 150 million years ago were over 3,000 ppm, and between 600 and 400 million years ago they were over 6,000 ppm, according to Climate Change 2001: The Scientific Basis. Historically, atmospheric carbon dioxide concentration fell slowly beginning about 60 million years ago. After an extinction event 34 million years ago, Antarctica’s ice sheet took its current form, when CO2 was about 760 ppm. Many of today climate scientists are telling us decreasing CO2 concentration to 600 ppm was no tipping point. Others say a level of 600 ppm was the primary factor in forming the ice sheets of Antarctica; I refer to Pagani, Mark; Huber, Matthew; Liu, Zhonghui; Bohaty, Steven M.; Henderiks, Jorijntje; Sijp, Willem; Krishnan, Srinath; Deconto, Robert M. (2 December 2011).”Drop in carbon dioxide levels led to polar ice sheet, study finds”. Science.334(6060): 1261–4.
Wagner et al. stated that atmospheric CO2 concentrations between 7,000–10,000 years ago were well over 300 ppm but correlated to temperature. Others have disputed such claims, suggesting they are likely to due to calibration issues. Maybe if we had a time machine I could go back in time to make better measurements.
There is so much conflict over real data and the computer models that cannot reproduce Earth history. There is no convincing argument, in my humble opinion.
Mark Kingston Levin PhD author of 30th Century series book 2 30th Century: Revived, which was release on Amazon April 29, 2018.
Dr. Levin won the IRWIN for the Best Science Fiction Book of 2017 for the first book in the series, 30th Century: Escape. To read the first three chapters, see www.markkingstonlevin.com.
For questions and comments write to Dr. Levin email@example.com
Dr. Levin was born and grew up in Vermont with many winters spent in Florida as a child. As a teenager he wrote poetry, served as a lifeguard and played football. He currently enjoys sailing, exploring underwater caves, snorkeling, writing science fiction and other pursuits. After working on the Apollo and Mars projects, he returned to school to study under Nobel Laureate Paul Dirac, obtaining his PhD in 2.5 years. Dr. Levin founded two companies and served the science policy apparatus in President Ford’s administration. He has been published over 44 times in scientific literature and was awarded over 32 US patents. The science fiction writer is now emerging with his first work, a trilogy titled 30th Century.
The first award-winning book, 30th Century: Escape, is currently available on Amazon both in its original erotic form BUY HERE and the new, toned-down General Audience Edition in both Kindle and in full-color print BUY PRINT HERE. Book two in the series, 30th Century: Revived, is available HERE in both e-book and print. Look for book 3 in the series, 30th Century: Contact, by early 2019!
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