climate past future
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This is a graphical interpretation by David Spratt, Melbourne Climate Action Centre,
of aspects of recent paleo-climate research by Hansen et al, available in draft form at:
http://arxiv.org/abs/1105.1140
http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf
http://www.columbia.edu/~jeh1/mailings/2011/20110514_PaleoAndImbalance.pdf
Version 1.5 of 6 June 2011
Eocene
peak
Our climate: past and future
Lessons from a warmer world
PETM natural
greenhouse event at55 million years ago.
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Antarctic glaciation ~ 34 million years ago
Eocene
peak
Around 34 million years
ago, glaciation ofAntarctica at tail-end of
protracted upper Eocenecooling.
Relativetemperature
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Around ~4.5 million years ago, northern hemisphere glaciation.
Associated with the rise of the Panama Cordillera which isolates
the Pacific from the Atlantic oceans and leads to intra-oceanic
circulation (Gyres) which introduces warm currents and moisture
to the North Atlantic resulting in increased snow fall and
formation of ice in Greenland, Laurentia and Fennoscandia.
Northern hemisphere glaciation ~ 4.5 million years ago
Eocene
peak
Relativetemperature
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The last million yearsClimate swings
between ice ages
and warm
inter-glacial periodsover last million
years.CO2 between 180
and 300 parts permillion.
Carbon dioxide
and methane
over last
500,000 years
Relativetemperature
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Peak of Holocene (over last 10,000 years up 1900AD)
The last 10,000 years the Holocene
PeakHolocene
temp.
Holocene: after the
last ice age, relativelystable temperatures
(+/0.5C) and sea-levels over last 10,000
years the period of
human civilisation
Relativetemperature
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Peak of Holocene (over last 10,000 years up 1900AD)
Global average temperature now ~0.6C above peak Holocene
Today temperature rises above the Holocene maximum
2010
CO2 level today (2011) is 391ppm but
thermal inertia (delay as ocean mass
warm) means temperature will increase
further.Temperatures have risen ~0.83C since
1900 and are now ~0.6C over peak
Holocene.
Relativetemperature
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Peak of Holocene (over last 10,000 years up 1900AD)
Global average temperature now ~0.6C above peak Holocene
2C of warming: consequence of current level of greenhouse gases
2 degrees goodbye to Greenland ice sheet
+2C
When climate system
reaches equilibrium,present level of CO2 will
produce >2C of warmingwith feedbacks
Relativetemperature
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Peak Holocene: over last 10,000 years up 1900AD
Global average temperature now ~0.6C above peak Holocene
2C of warming: consequence of current level of greenhouse gases
+2C
which is sufficient for large
parts of Greenland and West
Antarctic ice sheets to be lost,
leading to at least a 5-10 metresea-level rise over time
Goals to limit human-made
warming to 2rC.. are not sufficient
they are prescriptions for disaster
Dr James Hansen
Relativetemperature
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Peak of Holocene (over last 10,000 years up 1900AD)
Global average temperature now ~0.6C above peak Holocene
2C of warming: consequence of current level of greenhouse gases
4C of warming
4 degrees goodbye, goodbye
Best present emission reductioncommitments by all governments
(if implemented) will still lead to
4 degrees of warming by 2100
+4C
Relativetemperature
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Peak of Holocene (over last 10,000 years up 1900AD)
Global average temperature now ~0.6C above peak Holocene
2C of warming: consequence of current level of greenhouse gases
4C of warming
+4C
and likely loss overtime
of all ice sheets. No icesheets on planet = 70
metre sea-level rise overtime
amongst many devastating impacts.
Read more about 4 degrees hotter at
http://www.climateactioncentre.org/resources
Relativetemperature
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the alternative scenario (Hansen et al 2011)
6% annual reduction in CO2 emissions starting 2013 plus 100
billion tonnes of reforestation between 2031 and 2080
reduces CO2 to below 350ppm by end of century.
Source: The Case for Young People and Nature: A Path to a Healthy, Natural, Prosperous Future (draft paper) by
James Hansen, Pushker Kharecha, Makiko Sato, Paul Epstein, Paul J. Hearty, Ove Hoegh- Guldberg, Camille
Parmesan, Stefan Rahmstorf, Johan Rockstrom, Eelco J.Rohling, Jeffrey Sachs, Peter Smith, Konrad Steffen, Karina
von Schuckmann, James C. Zachos
http://www.columbia.edu/~jeh1/mailings/2011/20110505_CaseForYoungPeople.pdf
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