Ian Bradford: The Planetary Cycles That Affect Our Climate and Weather

A number of articles have mentioned that climate change and weather have always occurred right back in geological time. All occurring long before the existence of humans. For example, how many know that around 232-234 million years ago it rained continuously for between 1 million and 2 million years?

That’s quite extraordinary. It is called the Carnian Pluvial Episode (Late Triassic). The planet shifted from predominately arid conditions to a much wetter climate. It bought about significant evolutionary changes including the diversification of the early dinosaurs. The rainfall is believed to have been triggered by massive volcanic eruptions. It did not rain continuously every single day, but it did represent a sustained, intense rainfall over roughly 1 to 2 million years – the longest most significant wet period in Earth’s history. Then we have all the ice ages followed by warming periods, and records of extreme weather events. One has to ask what caused all these climate changes and weather events long before humans emitted carbon dioxide and cows emitted methane.

In the longer term, Milankovitch cycles describe the collective effects of changes in the Earth’s climate over thousands of years. These cycles are named after the Serbian physicist Milutin Milankovitch. In the 1920’s he provided a definitive and quantitative analysis that variations in the Earth’s eccentricity, axial tilt, and precession, combined to result in cyclical variations in the solar radiation at the Earth’s surface, and that this orbital forcing strongly influenced the Earth’s climatic patterns.

ECCENTRICITY



The Earth’s orbit is approximately an ellipse. Eccentricity measures the departure of this ellipse from a circular shape. When the path is a circle the eccentricity is zero. The highest eccentricity in the last 250 years was 0.0679. The major component of these variations has the earth’s eccentricity varying with a period of 405,000 years. Eccentricity is defined to be the distance between the two foci of the ellipse divided by the length of the major axis.



Eccentricity varies primarily due to the gravitational pull of Jupiter and Saturn. The semi- major axis of the orbital ellipse however, remains unchanged. Since the semi-major axis is constant when the Earth’s orbit becomes more eccentric the semi-minor axis shortens.

The Earth now has a closest distance to the sun - the perihelion and a farthest distance from the sun - the aphelion. At the present value of eccentricity, the incoming solar radiation, varies by about 6.8%. Variation in solar radiation is small factor in seasonal climate variation compared to axial tilt and to the relative ease of heating the larger land masses of the northern hemisphere. Kepler’s second law of planetary motion states that a body in orbit traces out equal areas in equal times. So, the body’s orbital speed is highest around perihelion and lowest around aphelion. This means the lengths of the seasons varies. For example, summer in the northern hemisphere is 4.66 days longer than winter. As the eccentricity increases, the seasons become more equal in length.

OBLIQUITY ( AXIS TILT)



The angle of the Earth’s axial tilt with respect to the plane of the orbit, varies between 22.1 degrees and 24.5 degrees. This occurs over a cycle of about 41,000 years. The current tilt is 23.44 degrees, roughly halfway between its extreme values. Ther last maximum was in 8700 BC which correlates with beginning of the Holocene, the current geological epoch. Increased tilt increases the amplitude of the seasonal cycle in isolation, providing more solar radiation in each hemisphere’s summer and less in winter. The current trend of decreasing tilt will promote milder seasons (warmer winters and colder summers), as well as an overall cooling trend. Because most of the planet’s snow and ice is at high latitude, decreasing tilt may encourage the termination of an interglacial period and lead to an overall cooler climate.

AXIAL PRECESSION



Axial precession is the trend in the direction of the Earth’s axis of rotation relative to the fixed stars, with a period of about 25,700 years. It is a kind of “wobble” of the axis. This precession is caused by the tidal forces exerted by the sun and moon on the rotating Earth. At present perihelion occurs during the southern hemisphere’s summer. This means that solar radiation due to both the axial tilt inclining the southern hemisphere towards the sun, and the Earth’s proximity to the sun will reach a maximum during the southern summer and reach a minimum during the southern winter. These effects mean that seasonal variation in irradiation of the southern hemisphere is more extreme

In about 13,000 years the north pole will be tilted towards the sun when the Earth is at perihelion.

The orbital ellipse itself precesses in space, completing a full circle in about 112,000 years This happens primarily as a result of interactions with Jupiter and Saturn.

As the orientation of the Earth’s orbit changes, each season will gradually start earlier in the year.

Milankovitch believed that obliquity had the greatest effect on climate, and it did so by varying the summer insolation (insolation is the amount of radiation reaching the Earth’s surface and atmosphere over a particular area and time), in northern high latitudes. Subsequent research has shown that ice age cycles of the Quaternary glaciation over the last million years have been at a period of 100,000 years, which matches the eccentricity cycle.

THE SOLAR CYCLE

This is often known as the sunspot cycle. It refers to the periodic variation in the sun’s magnetic activity and the number of sunspots on its surface. This cycle lasts about 11 years and has a profound effect on various aspects of the Earth’s climate conditions. Several studies suggest that solar variations can have noticeable effects on the Earth’s, weather patterns and climate system.



Solar activity is primarily driven by magnetic processes within the sun, leading to the formation of sunspots and the release of solar radiation. The sunspots are dark. They are dark because they are cooler than the surrounding areas. They are associated with intense solar activity. At the peak of the cycle, the number of sunspots is high, and solar radiation output is higher. Solar variations influence Earth’s climate through changes in Total Solar Irradiance – TSI. This refers to the amount of solar energy received per unit area at the outer atmosphere of the Earth. Small changes in the TSI associated with the solar cycle can have noticeable effects on our climate system. Variations in TSI reaching the Earth can directly influence the amount of energy reaching the earth, which in turn affects atmospheric temperature, cloud formation, and circulation patterns.

Solar irradiance can impact Earth’s climate through different mechanisms. One involves the influence of solar radiation on atmospheric temperature. Higher levels of solar radiation during the peak of the solar cycle can lead to increased heating of the Earth’s atmosphere, potentially affecting weather patterns and atmospheric circulation. Changes in solar radiation can also influence the vertical temperature structure of the atmosphere. During periods of high solar activity, the sun’s magnetic field is stronger, and more cosmic rays are deflected away from the Earth. Cosmic rays are high energy particles from space, primarily protons and atomic nuclei that travel near the speed of light, and interact with the Earth’s atmosphere. However, when sunspot activity is low, fewer cosmic rays are deflected and more cosmic rays reach the Earth’s atmosphere. Cosmic rays can potentially influence cloud formation by ionizing atmospheric particles. Clouds are essentially a collection of tiny water droplets. Water vapour is our most abundant “greenhouse” gas, and has a strong effect on the Earth’s temperature. High clouds that are thick, reflect sunlight back into space. Thin high clouds like cirrus let sunlight through. Variations in solar ultra violet (UV) radiation can influence the production and distribution of ozone in the atmosphere.

Changes in ozone concentrations can alter the temperature structure of the stratosphere, which can have downstream effects on the troposphere where weather occurs.

So the solar cycle has the potential to impact Earth’s climatic conditions through changes in solar radiation, cosmic rays, and ozone distribution. They all can contribute to short term climate variability.

THE 900 YEAR CLIMATE CYCLE

The approximately 900 period is closely related to three warm climatic periods in the last 2000 years: The Roman climate optimum of 25-400, the Medieval climate optimum of 950-1250, and the current warm period after 1980. During the two historical warm periods, the greatest reduction in Jupiter’s orbital eccentricity occurred while solar activity was high (Steinhilber,2009). In the current warm period, solar activity and Earth’s climate have a similar pattern to the two previous warm periods.

Extensive research is being done on the 900-year climate cycle. This may be the topic for a future article.

THE 88 AND 60 YEAR CLIMATE CYCLES

General temperature oscillations of a 60 to 90 year period have been under debate. A recently published study of Ollila and Timonen has found that these oscillations are real and that they are related to 60 and 88 year periodicities originating from the planetary and solar activity oscillations. These oscillations can be observed in the Atlantic Multidecadal Oscilllation ( AMO), the Pacific Multidecadal Oscillation (PMO), and in the global surface temperature (GST). Note: The AMO is defined by the water temperature in the Northern Atlantic (0-70 Deg C).

The following graph shows these 60-year fluctuations.



The oscillations are not limited only to temperatures. Researchers have studied day lengths, magnetic field magnitudes, sunspot lengths, auroral records, cosmogenic isotopes like C14 and Be10, Indian moon intensities, sediments of the North East Pacific, C14 in tree rings, and sea carbonates. The oscillation periods of these studies varies from 60 to 90 years The most common and prominent periodicity is 88 years and is called the Gleisberg cycle, named after Wolfgang Gleisberg, who discovered in 1958, that solar cycles weaken and strengthen over about 80 years.

The other main periodicity of the research studies is around 60 years. Research reveals that there is a 60-year oscillation in the majority of long tide gauge records. Research was done by Don Chambers, University of South Florida, Mark A Merrifield from the University of Hawaii, and R Stevens of the University of Boulder, Colorado.

They found there was a significant oscillation with a period of around 60 years in the majority of tide gauges examined during the 20th Century, and that it appears in every ocean basin.

This oscillation is consistent in phase and amplitude in many ocean basins. Because of this oscillation it is clear we may see a drop in sea level soon. It is at odds with the notion that sea level rise is accelerating.

The 60 and 88 year oscillations explain the well-known temperature oscillations for the 1900’s, and the studies show that the oscillations are a permanent phenomenon affecting the global surface temperature on a millennia scale. Note that the study utilized data from HadCRUT5.

The 60-year cycle is evident in global temperature records, with historical maxima around 1879, 1942 and 2002, and minima around 1910, and 1972. This cycle appears in multiple climate indicators including:

1. Global and regional temperatures. ( Schlesinger and Ramakutty, 1994)

2. Atlantic Mutidecadal Oscillation (AMO) reflecting North Atlantic surface temperature oscillations.

3. Ocean level variations and surface temperature anomalies.

4. Arctic climate patterns including alternating warm and cold epochs.

5. Tree ring reconstructions of summer temperatures in northern latitudes.

These observations suggest that the cycle is widespread and not limited to a single region or dataset.

Since this cycle is a regular occurrence, the next minima is going to be around 2032. Just taking tide levels for example the last maximum was in 1972. This cycle will be causing tide levels to fall, hence counter-balancing any rise due to a warming ocean. Jupiter is our largest planet, and its gravitational attraction affects all planets in our solar system. Scientists have found that there are changes in the eccentricity of Jupiter’s orbit every 60 years. This causes changes in the orbital rate of the Earth. A change in the spin rate of the Earth affects the motion of the atmosphere and the ocean. A slowing down of the rotation means the length of day is increased. This of course, is a very small amount. Changes in the length of day causes variation in the Coriolis force, which affects the rotation of the solid Earth, atmosphere, and ocean currents. Many scientific papers suggest that the Earth’s rotation rate is a key parameter that determines both climate and climate- independent geophysical changes (earthquakes, volcanoes etc).

At the small catchment scale, the rate of the Earth’s rotation significantly affects precipitation and runoff. A close relationship to changes in the Earth’s rotational rate has been demonstrated in the following phenomena:

1. 1992 El Chicon eruption

2. 1991 Pinatubo eruption

3. Occurrence of strong earthquakes in the period 1900-2022

4. AMO index

5. Low flows in the period 1920-2020 on the Punkva river in the Moravian Karst

6. Post 1995 rain extremes in the Czech Republic

7. Catastrophic floods 2002 in central Europe

8. Unusually long drought 2014-2019 in Central Europe.

A number of scientists believe the accumulation of extreme events (6 to 8) in a short period is due to a periodic climate change due to the gravitational interaction of solar system bodies on the earth and the sun.

It seems these cycles have caused weather events and climate change in the past. There is no reason why these cycles are not continuing. Their effect on weather and climate cannot be underestimated.

Ian Bradford, a science graduate, is a former teacher, lawyer, farmer and keen sportsman, who is writing a book about the fraud of anthropogenic climate change.