During the most recent ice age ocean levels were 400 feet below present levels

note: it's better to use the link I provide in this article simply because the pictures and illustrations of what earth looked like during this last ice age might be very helpful to you in understanding better what is written about here. end note.

The earth appears to go between ice ages and global warming like now. When the glaciers melt like now it often is a harbinger of a coming ice age for example. Though it's true that mankind creates global warming through the burning of fossil fuels, it is also true that before human fire prevention efforts, often fires never went out around the world and just kept burning until they either ran out of fuel or were put out by the weather, one of the two or both.

I'm thinking that fire prevention likely began with the building of houses and the farming of the land when people stopped being hunter gatherers and settled down one place or another. Before that likely they just walked away from the fires mostly and got into lakes and rivers and oceans as fires went by for safety. 

So, as we look at water levels rising now it could also be a harbinger of a future ice age that mankind will be facing too. So, as glaciers melt it also seems to be creating more vacillation in weather around the world both hotter but also sometimes colder.

For example, here in California this has been one of the coldest Decembers ever along the coast with temperatures into the 20s and 30s which is somewhat unusual because where I live for example the temperature almost never goes below about 39 or 40 degrees most winters. But, so far at least this winter has been exceptionally cold which is strange because winter doesn't officially start until December 21st I guess.

begin quote from:

The most recent glacial period occurred between about 120,000 and 11,500 years ago. Since then, Earth has been in an interglacial period called the Holocene.

Glacial-Interglacial Cycles

https://www.ncei.noaa.gov › sites › default › files

 

 

So, if the most recent ice age didn't end until 11,500 years ago you can see the problems that would have

been difficult to overcome for human beings if much of the world was covered by ice including all of China 

and Asia and all of North America and Europe covered by ice.

So, any human civilizations would have had to be south of Asia, North America and Europe in order to 

prosper as civilizations during this time. Also, with water 400 feet below now, when water started to roll 

over the earth and the oceans rose up it also would have wiped out some places (like Atlantis?) when this 

happened during some large storm maybe?

begin quote from above Link:

NOAA NATIONAL CENTERS FOR ENVIRONMENTAL INFORMATIONGlacial-Interglacial
Cycles
Large, continental ice sheets in the Northern
Hemisphere have grown and retreated many times
in the past. We call times with large ice sheets
“glacial periods” (or ice ages) and times without
large ice sheets “interglacial periods.”
The most recent glacial period occurred between about 120,000 and 11,500 years ago. Since then,
Earth has been in an interglacial period called the Holocene. Glacial periods are colder, dustier, and
generally drier than interglacial periods. These glacial–interglacial cycles are apparent in many marine
and terrestrial paleoclimate records from around the world.
What causes glacial–interglacial cycles?
Variations in Earth’s orbit through time have changed the amount of solar radiation Earth receives in
each season. Interglacial periods tend to happen during times of more intense summer solar radiation
in the Northern Hemisphere. These glacial–interglacial cycles have waxed and waned throughout the
Quaternary Period (the past
2.6 million years). Since the
middle Quaternary,
glacial–interglacial cycles
have had a frequency of
about 100,000 years
(Lisiecki and Raymo 2005).
In the solar radiation time
series, cycles of this length
(known as “eccentricity”)
are present but are weaker
than cycles lasting about
23,000 years (which are
called “precession of the
equinoxes”).
Comparison between summer ice coverage from 18,000 years BP (see, for example, Peltier 1994)
and modern day observations. Note that when more water is locked up in ice, more land is exposed
due to lower sea levels.
More Paleo Perspectives available here: ncei.noaa.gov/products/paleoclimatology/paleo-perspectives

Interglacial periods tend to occur during periods of peak solar radiation in the Northern Hemisphere
summer. However, full interglacials occur only about every fifth peak in the precession cycle. The full
explanation for this observation is still an active area of research. Nonlinear processes such as positive
feedbacks within the climate system may also be very important in determining when glacial and inter-
glacial periods occur.
Another interesting fact is that
temperature variations in Antarctica
are in phase with solar radiation
changes in the high northern
latitudes. Solar radiation changes
in the high southern latitudes near
Antarctica are actually out of phase
with temperature changes, such
that the coldest period during the
most recent ice age occurred at
about the time the region was ex-
periencing a peak in local sunshine.
This means that the growth of ice
sheets in the Northern Hemisphere
has an important influence on
climate worldwide.
Solar radiation varies smoothly through time (top, orange line) with a strong cyclicity
of ~23,000 years, as seen in this time series of July incoming solar radiation at 65°N
(Berger and Loutre 1991). In contrast, glacial–interglacial cycles last ~100,000 years (middle,
black line) and consist of stepwise cooling events followed by rapid warmings, as seen in
this time series inferred from hydrogen isotopes in the Dome Fuji ice core from Antarctica
(Kawamura et al. 2007). Atmospheric CO2 measured from bubbles in Dome Fuji ice (bottom,
blue line) shows the same pattern as the temperature time series (Kawamura et al. 2007).
Yellow columns indicate interglacial periods.
Why do glacial periods end abruptly?
Notice the asymmetric shape of the Antarctic temperature
record (black line), with abrupt warmings shown in yellow
preceding more gradual coolings (Kawamura et al. 2007;
Jouzel et al. 2007). Warming at the end of glacial periods
tends to happen more abruptly than the increase in
solar insolation. Several positive feedbacks are respon-
sible for this. One is the ice-albedo feedback. A second
feedback involves atmospheric CO2. Direct measure-
ment of past CO2 trapped in ice core bubbles shows
that the amount of atmospheric CO2 decreased during
glacial periods (Kawamura et al. 2007; Siegenthaler et
al. 2005; Bereiter et al. 2015), in part because the deep
ocean stored more CO2 due to changes in either ocean
mixing or biological activity. Lower CO2 levels weakened
the atmosphere’s greenhouse effect and helped to
maintain lower temperatures. Warming at the end of
the glacial periods liberated CO2 from the ocean, which
strengthened the atmosphere’s greenhouse effect and
contributed to further warming.
Some important datasets related to
glacial/interglacial cycles:
• Berger and Loutre (1991), calculated incoming
solar radiation for the last 5 million years
• Peltier (1994), ice sheet topography since the
last glacial maximum
• Lisiecki and Raymo (2005), benthic δ18O records
used as a proxy for global ice volume
• Siegenthaler et al. (2005), carbon dioxide from
the EPICA Dome C ice core in Antarctica
• Jouzel et al. (2007), stable isotopes from the
EPICA Dome C ice core in Antarctica
• Kawamura et al. (2007), stable isotopes and trace
gases from the Dome Fuji ice core
• Bereiter et al. (2015), carbon dioxide from the
EPICA Dome C ice core in Antarctica
@NOAANCEI @NOAANCEI and @NOAASatellites @NOAAData and @NOAASatellites
October 2021
Growth of ice sheets in the
Northern Hemisphere has an
important influence on
climate worldwide.