Transcript Medieval Warm Period - Natural Climate Change

Elizabeth Machado
 The
Medieval Warm Period (MWP) is the
name given to the warm period observed
in many parts of the world between 900
and 1200 AD.
 Also known by Medieval Climate Optimum
and Medieval Climatic Anomaly.
 The
warmest part of the Medieval Warm
Period was from about 950 until 1100 A.D.
 There was also a slight cooling from 10401080 AD known as the Oort Minimum.
Was a climatologist.
 Developed early theories of
Medieval Warm Period and
the Little Ice Age.
 1965 published “The Early
Medieval Warm Epoch and
its Sequel”.
 In this study he said that
there is evidence for a
warm climate followed by
cooling that lasted a few
centuries.
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The sun is the driving
force of climate
change.
The warm climate
overlaps with a time of
high solar activity
called the Medieval
Maximum.
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Also there was a
decline in volcanic
activity during this
time.
Less terrestrial dust
and sea spray in the
MWP than in the Little
Ice Age.
With warmer temperatures, agriculture was
possible at higher latitudes than is currently
possible in many regions.
 Bountiful harvests (such as grain) throughout
Europe during this time.
 Fig trees and olive trees grew in regions of
Europe (northern Italy and parts of Germany)
well north of their current range.
 Geological evidence indicates that mountain
glaciers throughout Europe retreated
substantially at this time.
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Central European vineyards have been found at
elevations more than 200 m higher than today,
indicating that summers were up to 1.5 °C
warmer.
This indicates that there was little or no frost in the
late spring, and summers that were relatively dry
and sunny.
This is confirmed by estimates of seasonal
temperature and rainfall compiled by Lamb, who
estimated the mean temperature for July and
August in central England from 1150 to 1300 at 16.3
°C compared with 15.8 °C for 1900–50.
Ice cores show that it was 1°C higher than today.
More land was
devoted to
agriculture.
 Population in Europe
increased by 50%.
 Economies grew.
 Vikings were able to
navigate to
Greenland because
of less ice in the
Atlantic.
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http://www.second-opinions.co.uk/images/viking-ship.jpg
http://www.culturalgadfly.com/wp-content/uploads/2009/12/plow_medieval-300x264.gif
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In Greenland, the
Norse settlers, arriving
around 1000 AD,
maintained a
settlement, raising
dairy cattle and sheep.
Encouraged by the
sight of pastures,
grasses and dwarf
woodlands of birch
and willow resembling
those at home.
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The discovery early in
the twentieth century
of plant roots and
Norse burial grounds
in subsequently frozen
soil suggests that
temperatures were 2–4
°C higher than in the
twentieth century.
Accounts told by
people.
http://upload.wikimedia.org/wikipedia/commons/thumb/1/17/Nicholas_Roerich%2C_Gu
ests_from_Overseas.jpg/800px-Nicholas_Roerich%2C_Guests_from_Overseas.jpg
Evidence shows that South Africa had a
warming from 900-1290 AD, which is the same
time as the MWP.
 East Africa was dryer than today.
 China also experienced warm temperatures
from 800-1400 AD and like Europe had a
prosperous economy.
 Pollen samples from different parts in the
world show that there was a general warming
in temperature during the Medieval Warm
Period.
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 MWP
was followed by the Little Ice Age
(1280-1850).
 Sea routes became tougher to navigate
because of ice.
 Difficult for the Norse to survive in
Greenland.
Dr. Deming published an article in 1995
that looked at the borehole temperature
data in North America.
 He concluded that the warming is still
within the range of estimated natural
variability.
 After this article he received an email from
a climate researcher that said they had to
get rid of the Medieval Warm Period.
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 http://www.youtube.com/watch?v=u
1rj00BoItw
“Current
evidence does not
support globally synchronous
periods of anomalous cold or
warmth over this time frame, and
the conventional terms of 'Little Ice
Age' and 'Medieval Warm Period'
appear to have limited utility in
describing trends in hemispheric
or global mean temperature
changes in past centuries".
Climate models used by the IPCC are
inaccurate and incomplete.
 The Medieval Warm Period and Little Ice Age
almost disappeared, replaced by a largely
benign, slight cooling trend that lasted until the
1900s.
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“Palaeoclimate science has made significant
advances since the 1970s, when a primary focus
was on the origin of the ice ages, the possibility of
an imminent future ice age, and the first
explorations of the so-called Little Ice Age and
Medieval Warm Period. Even in the first IPCC
assessment (IPCC, 1990), many climatic variations
prior to the instrumental record were not that well
known or understood. Fifteen years later,
understanding is much improved, more
quantitative and better integrated with respect to
observations and modeling”.
-IPCC
http://www.c3headlines.com/2010/06/2010-antarctica-peerreviewed-research-ice-core-data-confirms-medieval-period-warmer-than-present.html
This graph of ice cores from Dome C in Antarctica
shows that the MWP was 1°C warmer than current
temperatures.
 It also shows that climate change is driven by natural
forces and not caused by humans.
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 The
Medieval Warm Period was 1°C
warmer than today.
 The
IPCC, Michael Mann and others try to
deny the existence of this time even though
there is evidence that backs it up.
 Climate
change is driven by natural
forces not by humans.