It is a slow and mild Global Warming
It is a slow and mild Global Warming
What I have to complement is about the axial precession. Axial precession is the movement of the rotational axis of Earth.
According to the Milankovitch Cycle, precession has a cycle of roughly 21.170 years.
It is moving 1day every 58 years.
So we have 365 days * 58 years/day = 21.170 years
Precession doesn’t change the total amount of solar radiation that hits Earth. But precession primarily alters the perihelion and aphelion.
Overall, this increases the seasonal differences from one hemisphere to the other.
The warming trend we observe now started some 6.500 years ago. It is a very slow process.
The MWP ( the Medieval Warm Period ) is a confirmation of the existence of a long warming trend.
The LIA ( the Little Ice Age ) was observed as a colder atmosphere and more snowy winters. Also the glaciers were increasing. On the other hand oceans continued accumulating heat.
It is a very long cycle. We are observing the Reversed Milankovitch Cycle culmination period.
It will last about a millennia and a half and then there will be a cooling trend.
We are in a culmination phase phenomenon right now. It is similar to the common Solstice we observe every year...
Around Solstices the day is almost the same, only very tiny changes can be observed. It is a culmination time of a year. When day stops getting shorter and then it starts getting longer.
A very slow and small changes can be observed. The same with the 7.500 years long warming trend. It comes to its culmination now.
First it will stop to get warmer, and then very slowly it will change to a cooling trend. But as I have said it is a very long and a very slow process.
It will take some 1.500 years to complete. That is why I say there is an orbital forced Global Warming Trend. It is the 21.170 years long Milankovitch Cycle. Only the Milankovitch Cycle should be read Reversed!
At present Perihelion occurs in the middle of the Southern Hemisphere summer
At present Perihelion occurs in the middle of the Southern Hemisphere summer.
In the summer Earth's axis tilts toward sun.
At Perihelion Earth receives 7% more intense sunlight than at the Aphelion. This is because the Earth's orbit is not circular but elliptical, with the Sun located in one of the foci of the ellipse.
When we apply Stefan-Boltzmann Law we come to conclusion that at present, when Perihelion occurs in the middle of the Southern Hemisphere summer, Earth absorbs more solar energy and that leads to orbital forced warming trend.
It happens because North and South Hemispheres have an unequal distribution of land and oceanic surfaces.
The Southern Hemisphere is mostly covered with oceans (water) and the Northern Hemisphere is crowded with continents (soil).
As a result there is a major difference in each Hemisphere surface qualities.
The surface is what interacts with incoming solar flux. It is just happening that way at present.
cp. ocean = 1 cal /gr oC cp.
land = 0,19 cal /gr oC
Let's apply the Rotating Planet Surface Solar Irradiation Absorbing-Emitting Universal Law:
Jemit = σΤe⁴/(β*N*cp)¹∕ ⁴ (W/m²)
We can see now that when insolated, the land emits more intensively IR radiation back to space than the ocean does.
It is just happening that way at present.
When Southern Oceans are tilted towards sun Earth is at Perihelion (at closest to sun position). At present more intense insolation (+7%) falls on oceanic waters.
That leads to orbital forced global warming trend. It all happens according to Reversed Milankovitch Cycle.
And it happens according to Stefan-Boltzmann Law.
And of course the average global insolation remains reasonably constant.
Jabs = [ Φ (1-a) So /4 ] (W/m²)
What changes in the time is the Earth's surface IR radiation intensity. What changes in time is the intensity Earth gets rid from the incoming solar energy.
That is why I say there is an orbital forced Global Warming Trend. It is the 21.170 years Milankovitch Cycle. Only the Milankovitch Cycle should be read Reversed !