1. Climate the accumulation of daily and seasonal weather events over a long period of time
Past Climates - the mechanisms
Warmer and cooler periods are largely due to variations in Earth's orbit and tilt,
commonly referred to as Milankovitch cycles.
Axial Tilt (Obliquity)
The tilt of the Earth also changes slightly,
with a dominant cycle every 41,000 years.
The change in
angle is only
about 1° from
now, (23.5 to 24.5°) However, this
small tilt difference
results in large
differences in
solar radiation.
Eccentricity The shape of Earth's orbit becomes
more elliptical on time scales of
about 100,000 years. This ranges
from as 1% (a nearly circular orbit)
to 11%. Currently the maximum
difference between Sun-Earth
distances during the year is about 3%.
Precessions Earth wobbles on its axis about once every 26,000 years,
similar to a spinning top, altering the relationship between
the solstices and the distance from Earth to the Sun. For
example, 11,000 years ago the Northern Hemisphere summer
solstice occurred at perihelion, when the Earth is closest to the Sun.
(almost the exact opposite of today seasons) This "synching up" of
summertime with perihelion made the differences between winter
and summer much more pronounced.
White

2. Earth’s Current Climate
The maximum difference between Sun-Earth
distances during the year is about 3% and our
tilt angle is about
The distribution of the Sun's energy on Earth's surface changes throughout the year.
The Earth's tilt, or angle of inclination, determines the amount of solar energy a given region receives as it orbits the Sun Even though Earth is further from the Sun in June than January, the warmest season in the Northern Hemisphere occurs when the Earth is tilted toward the Sun.

3. Widespread acceptance of Milankovitch’s theories
occurred in the decades just after his death
when investigations of sea floor sediments and
the Vostok ice core exhibited periodicities matching
his calculations.

4. Antarctic Ice Core Record

5. Antarctic Ice Core Record