NOAA releases early update for World Magnetic Model

"What were are trying to understand is why we had this acceleration in the 1990s," Chulliat said. "They were caused by processes in the core that we don't yet understand."

--------------

I thought it was understood the acceleration was also the result of
the Christmas tsunamis which moved the earth axis about 4 degrees.
Or maybe not.

The 2004 Indian Ocean tsunami, according to the JPL, "should have shortened the length of day by 6.8 microseconds and shifted Earth's figure axis by about 7 centimeters, or 2.76 inches."

https://www.nasa.gov/topics/ea...e/earth20110314.html

Earth's figure axis is the "the axis about which Earth's mass is balanced".  A shift of 2.76 inches would be approximately 700 millionth (.000000068) of a degree.

If the scientists don't understand why there was (or is an ongoing) acceleration of  magnetic pole shift, I'll take their word for it.

 

RiverDance posted:

"What were are trying to understand is why we had this acceleration in the 1990s," Chulliat said. "They were caused by processes in the core that we don't yet understand."

--------------

I thought it was understood the acceleration was also the result of
the Christmas tsunamis which moved the earth axis about 4 degrees.
Or maybe not.

A 4 degree shift in the Earth's axis would eliminate the seasons as well as the 'temperate' zone and expand the tropics and the north and south poles about 100 mile each, respectively.

I believe that the tilt of the Earth's axis varies between 22.1-24.5o over 41,000 years:

The angle of the Earth's axial tilt with respect to the orbital plane (the obliquity of the ecliptic) varies between 22.1° and 24.5°, over a cycle of about 41,000 years. The current tilt is 23.44°, roughly halfway between its extreme values. The tilt last reached its maximum in 8,700 BCE. It is now in the decreasing phase of its cycle, and will reach its minimum around the year 11,800 CE.

Increased tilt increases the amplitude of the seasonal cycle in insolation, providing more solar radiation in each hemisphere's summer and less in winter. However, these effects are not uniform everywhere on the Earth's surface. Increased tilt increases the total annual solar radiation at higher latitudes, and decreases the total closer to the equator.

The current trend of decreasing tilt, by itself, 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 lies at high latitude, decreasing tilt may encourage the onset of an ice age for two reasons: There is less overall summer insolation, and also less insolation at higher latitudes, which melts less of the previous winter's snow and ice.

https://en.m.wikipedia.org/wiki/Milankovitch_cycles

Stanky posted:

I believe that the tilt of the Earth's axis varies between 22.1-24.5o over 41,000 years:

The angle of the Earth's axial tilt with respect to the orbital plane (the obliquity of the ecliptic) varies between 22.1° and 24.5°, over a cycle of about 41,000 years. The current tilt is 23.44°, roughly halfway between its extreme values. The tilt last reached its maximum in 8,700 BCE. It is now in the decreasing phase of its cycle, and will reach its minimum around the year 11,800 CE.

Increased tilt increases the amplitude of the seasonal cycle in insolation, providing more solar radiation in each hemisphere's summer and less in winter. However, these effects are not uniform everywhere on the Earth's surface. Increased tilt increases the total annual solar radiation at higher latitudes, and decreases the total closer to the equator.

The current trend of decreasing tilt, by itself, 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 lies at high latitude, decreasing tilt may encourage the onset of an ice age for two reasons: There is less overall summer insolation, and also less insolation at higher latitudes, which melts less of the previous winter's snow and ice.

https://en.m.wikipedia.org/wiki/Milankovitch_cycles

Gradual change is less problematic.  Instant change in the earth's axis would result in drastic changes in climate.

Add Reply

Likes (0)

×
×
×
×