Conferencia impartida por Vincenzo Pascucci el 1 de abril de 2011 en el marco de los Viernes Científicos, actividad organizada por la Facultad de Ciencias Experimentales de la Universidad de Almería
Paleoclimate: past-climate as the key to understand the future. Example from the Mediterranean Sea
1. PAST-CLIMATE AS THE KEY TO
UNDERSTAND THE FUTURE:
EXAMPLE FROM THE MEDITERRANEAN SEA
VINCENZO PASCUCCI
DIPARTIMENTO DI SCIENZE BOTANICHE, ECOLOGICHE E
GEOLOGICHE
UNIVERSITA’ DI SASSARI
pascucci@uniss.it
2. Climate is changing?
Which are the evidences?
Is this a normal process?
Which have been recent past climatic changes?
Which has been their impact?
Can we say something?
3. PATHWAY…
- ACTUALISM
1. PRESENT CLIMAT
2. CAUSES OF CLIMATE CHANGE
- PAST
1. GEOLOGICAL EVIDENCES OF
CLIMATE CHANGES (SARDINIA)
- CLIMATIC CHANGES OF THE LAST 125 KY
4. WHAT INFLUENCE THE CLIMATE OF THE EARTH:
1. EARTH ORBIT AROUND THE SUN
yearly
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2. LATITUDE & ALTITUDE
6. 3. GREAT OCEAN CONVEYOR BELT
500 year to make the all circuit
10. Orbital forces: short time
(thousand of years = long lasting changes)
today the Earth axis is 23°27’ inclined
Milankovitch
cycles
11. Sun spots (hundreds to tens of years 500-11y)
short time climate changes = sensible
The change in the number of sunspots and in solar activity
(deduced from studies of carbon-14 concentrations in the wood of
tree rings and of beryllium-10 in ice cores) suggests that there
have been various exceptional periods of solar weakness during
the last millennium, namely, the Wolf (around 1300), Spoerer
(around 1500), Maunder (between 1645 and 1715) and Dalton
(1800-1830) periods.
These low points were most likely preceded by a period of
maximum solar activity, the Medieval Solar Maximum (between
1100 and 1250) (Jirikowic, 1994). According to some authors, a
similar maximum, the Contemporary Solar Maximum, is
occurring right now and is caused by a rise in the magnetic
activity of the solar corona during the 20th century (Lockwood,
1999). Basing their conclusions on models, some authors believe
that the solar activity of the last 70 years is the most intense of the
last 8,000 years (Solanki, 2004).
2009
16. Main results are:
1. 8 glacial stages occurred during the last 740ky;
2. Interglacial past stages were as much warm as today;
3. Without human effect the present interglacial stage will last
other 15ky;
4. CO2 concentration is the highest of the last 444ky
17. What about CO2? Man has input more CO2
in the atmosphere in the
last 200y than the earth
system in 20ky… however
normally an increase of
CO2 into the system
precedes the beginning of
a glacial stage!!!!
CO2
T
18. Form Marine Isotopic Stages (MIS) to
Glacial and Interglacial stages: the last 300ky
…. Isotopic stages MIS (even=caluroso; odds=frio)…simple!!!
32. SEA LEVEL MARKERS AND DEER BONES INDICATE THAT
CAPO CACCIA CAVES WHERE FLOODED BY SEA RISE
AROUND 125KY AND SUBSEQUENTLY EMERGED DUE TO
SEA LEVEL FALL
52. SEA LEVEL CHANGES
• 125ky (MIS 5) SL was at least +4m higher than today;
• Since 80ky (end of MIS 5) sea level started to fall;
• It reached the max of -130 bpsl about 20-18ky (MIS 2);
• From 17-11ky sea level raised very fast (end MIS2);
• We are in a highstand since 10ky (MIS 1) that should last for
other about 15ky (without human influence)
53. TEMPERATURES AND CLIMATE
• 125-95 ky (MIS 5e) temp was at least +2/4 °C higher than today
(subtropical climate and beaches formation). Apex of interglacial;
• 90-80ky (MIS 5a) temp cooled down (-3/4 °C lower than today,
soils formation) (warm and humid). End of interglacial;
• 60-45ky (MIS 4) temp was -6/8 °C lower than today (cryoclast, u-
shaped valley, exposure of shelf and dune formation) (cold and
humiddry);
• 45-20ky (MIS 3-2) temp was -8/10 °C lower than today (wide
cryoclast deposits and dune formation) (cold and very dry) Apex
of glacial
54. C
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55. C
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57. SEA LEVEL FLUCTUATION DURING THE LAST
INTERGLACIAL 130-80 KY
(5 SUBSTAGES ABOUT 10KY EACH SEPARATED BY A
STRONG EROSIONAL UNCONFORMITY; 2 ASL, 1 BSL)
-bsl? +1m +4-6m
58. 10 ky cycles may be referred to:
• Subprecessional (or sub Milankovitch cycles);
– This short-time cycles can increase or decrease the
temperature of some degrees;
– At this moment it is not clear at all the origin of the
short-time cycles because very often they are non
linear and in cases they have been correlated to dust
aerosols present in the atmosphere);
– Solar irradiation variations;
59. Just an example: at the beginning of this interglacial,
in about 10 ky, the ice melted more or less completely.
This fast event is related to solar radiation changes.
60. SEA LEVEL RISE AFTER THE LGM (18KY)
…1 m rise every 100 years up to about 7/6ky, after that sea level
become more or less stable up to nowadays
61. …Y ITALIA SE CONVIRTIO’ EN BOTA!!!!
20ky ago In blu glaciers 6ky ago
62. Further studies
• Better characterize and explain the events occurred
during the last interglacial;
• Amount of dust in the past atmosphere;
• Solar irradiation variations (long and short time);
• Human impact on climate;
• Better understanding of the Atlantic Multidecadal
Oscillation (AMO) and if it existed also in the past (up
to now not older than 150y)….
• More money to geological research because our
future is written in the rocks and we only have
to find the way to dig it out!!!
63. Last example… thermal fluctuation of the
North Atlantic Ocean (AMO)
last 100 years
Mountain glaciers increase when AMO index is negative, and
retreat when AMO is positive
64.
65. Forecast based on past (BLU LINE)
Forecast based on global warming idea (RED LINE)
69. A possibility is also that someone is joking with us using
climate change as personal purpose to become famous!!!
70. ….but because
everybody wants
to speak about
climate…
GLOBAL WARMING EXPERCTS!!!
I did it too!!!!!!!
71. GRACIas
Le nuvole del cielo disegnano
la mia strada del ritorno,ma
solo tu raggio di sole sai quale
sia davvero.
Mi manca la tua luce, il tuo
calore, la tua bocca, il tuo
consiglio.
Questa notte solo naufragherò
tra i miei sogni dove spero di
incontrare la mia stella.
(Vince 07)
