Paleoclimate: past-climate as the key to understand the future. Example from the Mediterranean Sea
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 firstname.lastname@example.org
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?
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
WHAT INFLUENCE THE CLIMATE OF THE EARTH: 1. EARTH ORBIT AROUND THE SUN yearly
pCL eI rMA mT aIC n eBE nL tT 2. LATITUDE & ALTITUDE
3. GREAT OCEAN CONVEYOR BELT 500 year to make the all circuit
Orbital forces: short time (thousand of years = long lasting changes) today the Earth axis is 23°27’ inclinedMilankovitch cycles
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
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
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
Form Marine Isotopic Stages (MIS) toGlacial and Interglacial stages: the last 300ky …. Isotopic stages MIS (even=caluroso; odds=frio)…simple!!!
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)
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
CA CP AO P OCA CC AC CI CA I A20 TK OY D AA YGO
CA CP AO P OCA CC AC CI CA I A20 TK OY D AA YGO
SEA LEVEL FLUCTUATION DURING THE LAST INTERGLACIAL 130-80 KY(5 SUBSTAGES ABOUT 10KY EACH SEPARATED BY ASTRONG EROSIONAL UNCONFORMITY; 2 ASL, 1 BSL) -bsl? +1m +4-6m
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;
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.
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
…Y ITALIA SE CONVIRTIO’ EN BOTA!!!! 20ky ago In blu glaciers 6ky ago
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!!!
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
Forecast based on past (BLU LINE)Forecast based on global warming idea (RED LINE)
A possibility is also that someone is joking with us usingclimate change as personal purpose to become famous!!!
….but because everybody wants to speak about climate…GLOBAL WARMING EXPERCTS!!! I did it too!!!!!!!
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)