According to Peter Klevius research, it was the Gulfstream that caused the Eurasian snow cover which together with Milankovich cycles explains the onset of the last ice ages. Cooling via a thin but longer lasting snow cover can trigger the next ice age extremely quickly - global warming can not!
It's the very existence of the Antarctic glacier after the Eocene maximum and the Greenland glacier after around 20 Ma - when the Caribbean first started to disrupt the free ocean flow between South- and North America - that functions as a "capacitor" which explains why the global cooling gets worse over time. Antarctic glaciation was a consequence of ocean circulation and Greenland because of the Gulfstream (see text below).
If
you blindly follow CO2 - which you shouldn't - no glacial inception is
projected to occur at the current atmospheric CO2 concentrations of 390
ppmv. Indeed, model experiments suggest that in the current orbital
configuration—which is characterized by a weak minimum in summer
insolation—glacial inception would require CO2 concentrations below
preindustrial levels of 280 ppmv. However, CO2 increase in the past
interglaciations was a consequence of a diminished snow cover over
Northern Eurasia which led to increase in vegetation and CO2 before
glaciation. Whereas glaciers need a long time to melt, snow melts
immediately when temperature allows - including warm rain that can melt
much colder snow. And immediately when the snow disappears, vegetation
starts to grow. This is why ice core information based on glaciers has a
delay which makes it appear that CO2 could be initially involved -
which it wasn't because first the snow had to melt.
Whereas
interglaciations are characterized by exceeding precipitation, ice ages
are arid. So contrary to "global warming warnings", we should prepare
for every next year possibly being the last before the steep fall into
the next ice age.
Since farmers started clearing land for plants
and flooded fields to grow rice while cattle breeders began to raise
livestock, they also contributed to altering the climate - long before
the industrial revolution - of which led to a rise in the atmospheric
emission of carbon dioxide and methane. Without this human influence,
and the following Industrial Revolution, Earth may already been headed
for the next ice age.
However, the pressure from the natural
oscillations is overwhelming any human activity when considering the
effect of a volcano eruption in the midst of present interglacial 12,880
bp which managed to trigger the Younger Dryas - which climate hysterics
now wrongly use to call "the last ice age" and therefore equally
wrongly implying we have plenty of time before the next ice age.
The science of snow cover
An
anomalous “north-south” dipole mode of the snow water equivalent (SWE)
persisting from winter to spring in the Eurasian mid-to-high latitudes
contributes to prolonged winter-springtime coldness in midlatitude
Eurasia and is closely linked to the declining November Arctic sea ice
concentration over the Barents-Laptev Seas which can induce a
teleconnection pattern over the mid-to-high latitudes in the following
winter, accompanied by an anomalous ridge over the Ural Mountains and an
anomalous trough over Europe and East Asia. Such changes in the
large-scale circulation lead to more cold surges and heavy snowfall in
the midlatitudes and light snowfall in the high latitudes, forming an
anomalous north-south dipole mode of the SWE, which further reduces the
temperature through thermodynamic feedback. Due to seasonal memory, this
SWE pattern can persist into the following spring and can lead to
springtime midlatitude coldness via thermodynamic and dynamic processes
for which the anomalous SWE condition can lead to anomalous wet soil,
reduced incoming surface solar radiation, and cooling air in the
midlatitudes. This phenomenon induces an enhanced Siberian high and a
deepened East Asian trough via the snow-Siberian high-feedback
mechanism, which favors a cold spring in northern East Asia.
This
mechanism interacts with the Milankovich cycles in a pattern that,
although not fully understood, is visible in the increased amplitude of
regular glacial-interglacial oscillations in the Pleistocene after the
Panama isthmus closed entirely. This closing led to the strengthening of
the Gulfstream or Atlantic Meridional Overturning Circulation
(AMOC)—one of Earth’s major ocean circulation systems which has a major
impact on the climate of especially Northern Europe.
Peter Klevius' simplified climate model based on facts we already have:
1.
Earth's temperature has steadily gone down since Eocene 50 Ma due to
tectonics disturbing the ocean flow between Africa and Eurasia while
opening up the ocean flow around Antarctica which turned it from green
to an all covering glacier.
2. The oscillations have steadily
increased in amplitude with top temperature stabilizing while ice age
temperatures continue to fall.
3. The mechanism behind changing
Pliocene-Pleistocene oscillations is due to a combination of a) the
closing of the Caribbean ocean flow which triggered the Gulfstream more
strongly to the North, and b) snow cover or lack thereof over Northern
Eurasian lowland, and c) Milankovitch cycles.
4. The latest pattern started around 3 Ma which is exactly when the Homo lineage appeared - see:
https://peterklevius.blogspot.com/2023/01/how-pliocene-pleistocene-panama-isthmus.html
Peter Klevius wrote:
Wednesday, May 9, 2018
Klevius predicts: Singularity will arrive sooner than most expect - but a new iceage may start even sooner.
Have humans prolonged the onset* of the next ice-age to a breaking point?
* Do realize the treacherous behavior of snow cover. It can be extremely thin while the reflective effect is still 100%. It can jump in and out of meteorological records without being always noticed (in Sweden no records are kept after mid May). It can expand even when temperature goes up, due to increased precipitation in cold but usually dry areas. And snow cover can expand horizontally thousands of kilometer in no time.
Updated map 2021:
caused activities) must have some effect on the atmosphere - although this effect could suddenly drown in other "natural" effects (compare the butterfly flapping a hurricane).
Klevius analysis (from from the 1980s and on the web 2006): The Gulf stream is loosing stamina, meaning more snow cover lingering longer. This leads to extremely fast onset of cooling and due glaciation. A reported 15% decrease means we're in for cooling business. Changing rotational axis etc. longterm phenomenon can easily be outperformed in a shortterm scenario through local changes in precipitation combined with just a slight drop in temperature. Fennoscandia, northern Russia and Canada constitute such potentials (compare previous little and big ice-ages), especially at a time when we've already passed the usual tipping point.
We are way overdue with the coming of the next ice-age. Could it really be that we during Holocene have managed to keep it at bay? In Klevius book Demand for Resources (1992) he also wondered why humans didn't become modern already at the previous heat peak some 120 kyr ago? The big skulls were already there. Today Klevius theory on human evolution has the answer.
Due to the polemic nature of the mostly bi-facial approach to climate change, facts are either exaggerated or toned down. So for example, is the relation between the hemispheres often hidden as global or even presented with a confusing mix of Celcius and Fahrenheit for the sole purpose of "weighing" a certain stand point.
Indian ocean is the only one disconnected from the north and therefore reflects what Klevius wrote about 2006.
Snow cover is the opposite to CO2 - but much quicker.
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