"It's the unknown threat that's often the real danger" Right now all eyes are on the threat of
global warming but an even bigger problem would be catastrophic global cooling abrupt global cooling
is science fiction to most best represented in culture by the movie The Day After Tomorrow in
this movie north Atlantic ocean circulation shuts down ushering in a new ice age with temperatures
quickly plunging below -150 degrees centigrade highly exaggerated but with a hint of truth if
severe global cooling were to happen crops would fail weather would become highly unpredictable and
the environment as we know it would be radically changed forever currently we're experiencing
the opposite effect the Earth is rapidly warming with record highs being recorded year after year
in the arctic regions temperatures are increasing twice as fast as the rest of the planet
rapidly melting the ice stored there and that's the issue as rapidly melting ice may
be the cause of a future cold snap the first bit of evidence that global cooling may be a
big surprise of the near future is observed off the southern coast of Greenland where melting
icebergs have been reducing temperatures of the north Atlantic amongst the larger warming trend
in fact that's the same part of the Atlantic ocean where we first found evidence of past
extreme climate fluctuations known as Heinrich events. Heinrich events are estimated to last
250 to 500 years in length and have occurred at least six times over the past 60 thousand years
Heinrich events are characterized by the destabilization of northern ice sheets
resulting in massive discharges of meltwater and icebergs into the north Atlantic ocean
as these armadas of icebergs melted the lithic sediments trapped in the ice were freed and
settled to the bottom of the north Atlantic ocean into what are now known as Heinrich layers
geologists were stunned when they first observed these massive periodic surges of
ice-rafted detritus in sediment cores against the backdrop of normal fine-grained marine sediments
Heinrich layers indicated vast and rapid changes to the northern cryosphere at regular intervals
Heinrich layers line up with other worldwide changes that stand out in the geologic record
such as catastrophic flooding more vigorous atmospheric circulation
sharp reductions in sea surface temperatures rising sea levels and even ocean anoxia events
though there is variability in the evidence in dating of Heinrich events the best estimates
currently are that the last Heinrich event H1 occurred approximately 14,000 years ago
H2 was approximately 21,000 years ago H3 31,000 years ago H4 38 000 years ago h5 45,000 years ago
and H6 60,000 years ago the timing and number of Heinrich events is controversial and I want to
note that much of the information on the internet and wikipedia incorrectly cites the dates given in
Sidney Hemming's 2004 Heinrich event meta-analysis which is the best resource currently available
calculating the time between the past six Heinrich events of the last 60,000 years establishes a
reoccurrence interval of Heinrich events happening every 7,000 to 15,000 years Heinrich events
typically occur within long duration cold spells and it takes at least a thousand years of cooling
to build up enough ice sheet volume for a Heinrich event to trigger and it's been 14,000 years since
the last one there are many possible explanations for how Heinrich events start and what's better
understood is the mechanism of how huge volumes of ice can be transported so quickly out to sea
the rapid purge cycle characteristic to Heinrich events can occur once the bedrock at the bottom
of a glacier or ice sheet is sufficiently lubricated with meltwater underneath the ice
the fresh water drains to the ocean and being less dense it rises to the surface as a plume
these plumes draw in warmer salt water and melt the ice from the bottom up eventually resulting
in the calving of an iceberg as icebergs float away and melt ice sheets have space to advance
and the cycle continues inexorably discharging huge volumes of ice over time
if we examine the last Heinrich event approximately 14,000 years ago
it was primarily the North American Laurentide ice sheet that was being ejected into the ocean
at over 2 miles thick the laurentide ice sheet was massive its increased discharge over many hundreds
of years caused global sea levels to rise between 15 to 25 meters this huge flux of fresh water into
the north Atlantic reduced ocean salinity and with the water there now being less dense deep water
circulation was greatly reduced north Atlantic deep water circulation is an integral part of
worldwide ocean circulation being connected to the gulf stream and other major ocean currents
reductions in deep water circulation has major impacts on global heat convection
and its changes to deep water ocean circulation that may cause a downward
spiral in global temperatures in the near future while the Laurentide ice sheet no longer exists
Greenland still houses an immense amount of ice a rapid discharge of the Greenland ice sheet would
qualify as a Heinrich event ocean circulation would be altered similar to the paleolithic past
and colder climate conditions would sweep across much of the northern hemisphere
during past Heinrich events these factors stress the biosphere and Heinrich events are linked
with megaphone extinctions and the death of the Neanderthals there are many proposed variables for
how Heinrich events are triggered from asteroid impacts to the release of greenhouse gases every
Heinrich event was unique and likely was started by a multitude of factors culminating to create a
trigger of sufficient strength one of the possible triggering factors are magnetic excursions
when magnetic poles wander global electromagnetic currents which huge amounts of energy flow along
are altered which may have an effect on earthquake activity in addition to this reduced field
strength is observed during magnetic excursions increasing the earth's susceptibility to climate
altering solar events like coronal mass ejections during the past 60,000 years magnetic excursions
have often occurred alongside Heinrich events 12-14,000 years ago was the Gothenburg magnetic
excursion and this lines up with the H1 Heinrich event meanwhile 30-33,000 years ago was the
Mono Lake magnetic excursion and this lines up with the H3 Heinrich event 41-45 000 years
ago was the Laschamp magnetic excursion and this lines up with the H5 Heinrich event and 60,000
years ago there is a possible magnetic excursion which lines up with the H6 Heinrich event
the current movement and reduced strength of the Earth's magnetic field is leading many
geophysicists to believe that we're experiencing the beginning of a magnetic excursion right now
a troubling sign when magnetic excursions are well correlated with Heinrich events
and so the evidence stacks up enough for a global cooling scenario to no longer be ignored rapidly
warming polar regions are destabilizing ice sheets which are melting into the ocean reducing deep
water circulation and therefore overall global heat convection the weakening magnetosphere is
increasing to influence coronal mass ejections and other space weather have on Earth's climate
and all the while greenhouse gas concentrations in the atmosphere are reaching levels not seen in a
million years while the possibility of a Heinrich event and widespread global cooling is increasing
for the near future afterwards the end result would likely be even warmer temperatures worldwide
with less reflective ice cover global albedo would be reduced and the Earth would absorb greater
amounts of solar radiation than it does currently it was the last Heinrich event in the melting of
the Laurentide ice sheet which eventually brought about a period of global warming that led to the
current sea levels and coastlines which are familiar to us today humanity was thrust out
of the ice age and into a warmer interglacial period and what we've done since then has been
truly amazing while perhaps future climate events may play out similar to The Day After Tomorrow the
end destination of all this may be more similar to Kevin Costner's Waterworld personally I'd prefer we
avoid both of these outcomes and instead learn how to responsibly manage the energy systems we play
with globally notwithstanding my optimism that humanity can pull together to greenify the planet
we have to accept that we're helplessly caught in the winds of fate so my advice to everyone
is to be prepared and to leave the earth a better place than when she found you I hope
you enjoyed this video introduction to Heinrich events and my breakdown on the possibility
of a global cooling scenario the purpose of this video is not to alarm but to educate
to learn more research papers and other resources are linked in the video description sign up to my
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