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Global Warming –Beyond CO2:
The Chilling Stars
Henrik Svensmark,
Center for Sun Climate Research
Danish National Space Center
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Basel 2007
Global surface temperature
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How STARS influence Climate
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Heliosphere, Cosmic Rays and Solar Activity
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Cosmic ray shower
About 70 muons/s /m2 at the Earths surface
In 24 hours about 12 million muons goes through a human body
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Cosmic Rays in a Cloud Chamber
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Cosmic rays and climate over the last millennium
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Cosmic rays and climate over the last 10.000 years
Bond et al, Science 294, 2001
Last 1000 years
Little Ice Age
• Little Ice Age is merely the most recent of a dozen such events during the
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last 10.000 years
Indian Ocean monsoon
• Solar/GCR forcing of
Indian Ocean monsoons
on centennial—even
decadel—timescales
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Solar/GCR signal in 20th century warming
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Summary
• Evidence for GCR-climate association on all
timescales of Earth’s history
• Diversity and quality of evidence appears to
exclude mere chance association
• Key challenge is to establish the physical
mechanism
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Possible physical mechanism
• Mechanism that amplifies tiny
GCR energy input
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Solar variability
• No evidence for long-term
variations of solar irradiance
/UV beyond 11-yr cycle
• Recent factor 5 reduction of
estimated solar variability
since Maunder Minimum
(LIA)
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Coronal Mass Ejections (CME)
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One month of observation
Increase in open solar magnetic flux over the past
century
Open solar
magnetic flux
back in time
reconstructed
from
geomagnetic
activity
Magnetic flux
has increased
a factor of 2.3
over the last
100 years
Since 1963 an
increase of 1.4
Lockwood, Stamper, & Wild, Nature,
1999.
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Global surface temperature
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Link between Low Cloud Cover and Galactic Cosmic Rays?
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Svensmark & Friis-Christensen, JASTP 1997, Svensmark, PRL 1998, Marsh & Svensmark, PRL, 2000. (update 2005)
• Clear association of climate change and 10Be
/14C variability (cosmic rays):
high cosmic ray flux
cool climate
low cosmic ray flux
warm climate
• Monsoon rainfall seems especially sensitive
• But is 10Be /14C variability indicating
• a direct effect of cosmic rays on climate? or
• a proxy for solar variability (irradiance /
UV)?
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Location of the Solar systems in the Milky Way
Relevant for climate?
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Earth’s climate the last 500 million years
Veizer, et al. Nature 2000
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Estimated Cosmic Ray Flux
Cosmic rays and spiral arm crossing
0
0.5
1
1.5
600
200
400
Million of Years
0
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Shaviv, PRL (2002)
Cosmic rays and spiral arm crossing
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0
4
0.5
0
1
1.5
-4
600
200
400
Million of Years
Estimated Cosmic Ray Flux
Sea Surface Temperature Anomaly
0C
0
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Shaviv & Veizer
Jordens temperatur gennem 500 millioner år
Gennem 500 millioner år har
fossiler gemt information, i
deres skaller, om hvor varmt det
var da de levede
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What about longer time scales, i.e over
the history of the Earth 4.6 Billion years?
Although Cosmic ray fluxes are not known so far back
in
time, they can be constructed from knowledge of
1. Solar Evolution
2. History of Star Formation Rate in the Milky Way
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Solar Evolution, Star Rate Formation and Cosmic Rays
Outside the Heliosphere
SFR
CR
At Earth
CR
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Svensmark, 2003
Interaction between galaxies
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Cosmic Rays in 4 Billion Years
10 GeV
C = 0.92
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Svensmark, 2006
Carbon Isotopes
The various reservoirs of carbon on Earth
(limestone, biota and CO2 in atmosphere)
If more carbon is stored in one of
these reservoirs, the isotopic
composition of others reservoirs
changes to reflect that storage. For
instance: if there is more carbon
stored in organic matter which is
isotopically light, the average
carbon composition of dissolved
carbon in the ocean and carbon
dioxide in the atmosphere
will become heavier.
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Carbon 13 during 3.8 billion years
Standard
deviation
In steps of
400 mill yr
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Svensmark, Submitted PRL 2005
Cosmic Rays in 4 Billion Years
10 GeV
C = 0.92
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Svensmark, Submitted PRL 2005
Cold Climate
Large temperature difference between equator and pole
Strong winds – Mixing of Nutriants
Large biological productivity
Large fluctuations biological productivity possible
Warm
Cold
Ice
Equator
Pole 32
Hot Climate
Small temperature difference between equator and pole
Weak winds – Little Mixing of Nutriants
Small biological productivity
Small fluctuations in biological productivity
Hot
Equator
Warm
Pole 33
Conclusion
Particles from space seems to influence Earths climate,
ranging from years to 109 years.
A part of the missing physical mechanism has been
demonstrated experimentally
• Involving ions and aerosol formation
• Linking to clouds and thereby the energy budget of the Earth
Understanding the cosmic ray climate link could have large
implications in our understanding of climate changes and
possible evolution on Earth.
The evolution of the Milky Way and the Earth is linked
It is not suggested that it is the only cause of climate change.
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Skydække i %
IPCC: Model beregninger af Jordens skydække
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Temperatur udviklingen i atmosfæren:1979 - 2006
Øvre troposfære
Middel af troposfære
Nedre troposfære
Overflade
Observationer og modellering fra 49 ”eksperimenter” med 19 klimamodeller
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Temperature Trends in the Lower Atmosphere:
Steps for Understanding and Reconciling Differences, 2006
Solar activity (October 2003) EUV (1.5 mill K)
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Cosmic rays and climate over the last 10.000 years
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