Ricostruzione del clima del passato - Qui i contributi

**highway to hell** · 22/03/2007, 15:53

Central Scandinavian Mountains, Sweden
Reference
Linderholm, H.W. and Gunnarson, B.E. 2005. Summer temperature variability in central Scandinavia during the last 3600 years. Geografiska Annaler 87A: 231-241.

Description
Summer temperatures were inferred from a tree-ring width chronology derived from living and subfossil Scots pines (Pinus sylvestris L.) sampled close to the present tree-line in the central Scandinavian Mountains (63°10'N, 12°25'-13°35'E) spanning the time period from 2893 BC to AD 2002.

Between AD 900 and 1000, summer temperature anomalies were as much as 1.5°C warmer than the 1961-1990 base period.

**highway to hell** · 22/03/2007, 15:58

Lake Redon, Central Pyrenees, Northeast Spain

Reference
Pla, S. and Catalan, J. 2005. Chrysophyte cysts from lake sediments reveal the submillennial winter/spring climate variability in the northwestern Mediterranean region throughout the Holocene. Climate Dynamics 24: 263-278.

Description
The authors analyzed chrysophyte cyst data collected from a sediment core obtained from Lake Redon (42.64°N, 0.77°E) in the Central and Eastern Pyrenees of northeast Spain, producing a history of winter/spring temperatures for this region throughout the Holocene.

The Medieval Warm Period (~ AD 875 to 1000) was categorized as the "warmest period" of the record, with temperatures about 0.25°C warmer than it is currently.

Enrico_3bmeteo · 22/03/2007, 16:04

Originariamente Scritto da Jadan

Appunto: secondo questo articolo l'ottimo medievale comincia 20 anni dopo l'anno che, per Giraudi, ne segna la fine (Giraudi parlava di un ottimo medievale che finiva nel 1030).

Esattamente: Giraudi estimated that the mean annual temperature on higher Apennine massifs in Italy (42°23'N, 13°31'E) from approximately AD 700 to 1030 were "higher than at present," and that winter temperatures were "at least 0.9°C higher" than those of today.

Beh, coincide con la fase del Gorner. Quindi, mi sembra corretto.
Tieni presente che si riferisce al Gran Sasso, non al mondo intero.

**highway to hell** · 22/03/2007, 16:05

Northwest Spain Peat Bog
Reference
Martinez-Cortizas, A., Pontevedra-Pombal, X., Garcia-Rodeja, E., Novoa-Muñoz, J.C. and Shotyk, W. 1999. Mercury in a Spanish peat bog: Archive of climate change and atmospheric metal deposition. Science 284: 939-942.

Description
Mean annual temperatures were inferred from a record of mercury deposition in a peat bog in northwest Spain (43°32'N, 7°34'W) spanning the last 4000 radiocarbon years.

The Medieval Warm Period occurred between AD 1000 and 1200 and the mean annual temperature during this time was as much as 3.4°C warmer than that of the 1968-98 period.

**highway to hell** · 22/03/2007, 16:08

Spannagel Cave, Central Alps, Austria
Reference
Mangini, A., Spotl, C. and Verdes, P. 2005. Reconstruction of temperature in the Central Alps during the past 2000 yr from a δ18O stalagmite record. Earth and Planetary Science Letters 235: 741-751.

Description
Mangini et al. (2005) developed a highly-resolved 2000-year record of temperature with better than decadal resolution from a stalagmite recovered from Spannagel Cave in the Central Alps of Austria (47.09°N, 11.67°E).

The highest temperatures of the past two millennia occurred during the Medieval Warm Period (AD 800-1300) and were "slightly higher than those of the top section of the stalagmite (1950) and higher than the present-day temperature."

In fact, at three different points during the MWP, their data indicate temperature spikes in excess of 1°C above present (1995-1998) temperatures of 1.8°C.

**Jadan** · 22/03/2007, 16:09

Originariamente Scritto da highway to hell

The Medieval Warm Period (~ AD 875 to 1000) was categorized as the "warmest period" of the record, with temperatures about 0.25°C warmer than it is currently.

Originariamente Scritto da highway to hell

Lake Teletskoye, Altai Mountains of Southern Siberia

The Medieval Warm Period was identifed as a climatic period evidenced between the start of the authors' record in 1210 AD and ending around 1480 AD that was "warmer and more humid than today."

Allora, Highway to hell, capisco che a te il soliloquio piaccia molto, così come l'inondare di messaggi un thread quando, in certi casi, la segnalazione di un link sarebbe molto più costruttiva e rispettosa degli altri.

Ma tu stai continuando a postare articoli che definiscono l'ottimo medievale o MWP in maniera del tutto differente. Ne ho presi due, ma potevo farti un multiquote molto più lungo. Nel primo (Pirenei) il MWP va dall'875 al 1000. Nel secondo, Asia Centrale, lo stesso MWP comincia nel 1210 e finisce nel 1480.

Ora, non discuto i dati ma dare lo stesso nome a due cose completamente diverse è un po' buffo. Ci saranno certamente ragioni geogriafiche che spiegano tale discrepanza ma una cosa è certa: NON è lo stesso fenomeno. O è MWP il primo o lo è il secondo...

Abbiamo capito che vuoi postare tutti gli articoli che parlano di unperiodo più caldo di quello attuale. Ma, come ti ho detto, per quanto tu possa affogare questo thread, non è che la cosa muti di molto le discussioni. Soprattutto se poi posti articoli che giocano coi secoli come fossero brucolini.

**highway to hell** · 22/03/2007, 16:11

Tagus River Estuary, off Lisbon, Portugal

Reference
Abrantes, F., Lebreiro, S., Rodrigues, T., Gil, I., Bartels-Jónsdóttir, H., Oliveira, P., Kissel, C. and Grimalt, J.O. 2005. Shallow-marine sediment cores record climate variability and earthquake activity off Lisbon (Portugal) for the last 2000 years. Quaternary Science Reviews 24: 2477-2494.

Description
Sea surface temperatures, river discharge and biological productivity were reconstructed in a multi-proxy analysis of a high-resolution sediment core obtained from the Tagus River estuary near Lisbon, Portugal (~ 38.56°N, 9.35°W).

The MWP was identified as occurring between AD 550 and 1300, during which time interval mean sea surface temperatures were between 1.5 and 2°C higher than the mean value of the past century, while peak MWP warmth was about 0.9°C greater than late 20th-century peak warmth.

**highway to hell** · 22/03/2007, 16:12

Voring Plateau, Eastern Norwegian Sea
Reference
Andersson, C., Risebrobakken, B., Jansen, E. and Dahl, S.O. 2003. Late Holocene surface ocean conditions of the Norwegian Sea (Voring Plateau). Paleoceanography 18: 10.1029/2001PA000654.

Description
August surface temperatures of the eastern Norwegian Sea's Voring Plateau (66.97°N, 7.64°E) were derived from planktic stable isotopes and foraminiferal assemblage concentrations.

The Medieval Warm Period occurred between AD 1200 and 1500 and was as much as 3.3°C warmer than the Current Warm Period.

**Jadan** · 22/03/2007, 16:14

Originariamente Scritto da Enrico_3bmeteo

Beh, coincide con la fase del Gorner. Quindi, mi sembra corretto.
Tieni presente che si riferisce al Gran Sasso, non al mondo intero.

Certamente, ma come dicevo poco sopra, se è MWP un riscaldamento tra l'800 e il 1000, non può essere MWP un riscaldamento avvenuto agli antipodi tra il 1250 e il 1500. Quando nel 1000 qui faceva caldo (è assodato) cosa faceva agli antipodi?

Ricordiamoci che noi parliamo di aumento medio globale delle temperature. Se in un posto ha fatto più caldo rispetto a oggi nel IX sec. e in un altro nel XIII sec. può benissimo essere che, in media e globalmente, OGGI faccia più caldo sia del IX che del XIII secolo globalmente intesi. Anche se, sia in un secolo che nell'altro, c'erano luoghi in cui faceva più caldo di ora.

Non so se riesco a spiegarmi ma è veramente difficile dialogare con le lenzuolate che separano un messaggio dall'altro...

**highway to hell** · 22/03/2007, 16:15

Berre Lagoon, France
Reference
Robert, C., Degiovanni, C., Jaubert, R., Leroy, V., Reyss, J.L., Saliège, J.F., Thouveny, N. and de Vernal, A. 2006. Variability of sedimentation and environment in the Berre coastal lagoon (SE France) since the first millennium: Natural and anthropogenic forcings. Journal of Geochemical Exploration 88: 440-444.

Description
Mineral and microfossil assemblages from a sediment core taken from the Berre coastal lagoon in southeast France (~ 43.44°N, 5.10°E) were analyzed in an effort to reconstruct environmental changes in the region over the past 1500 years.

The MWP was identified as an interval of higher kaolinite content between AD 980 and 1370, which was judged to be indicative of "increased chemical weathering in relation to higher temperatures and/or precipitation."

In addition, the concentration of microfossils of the thermophilic taxon Spiniferites bentorii peaked during this period, which combined evidence leads us to conclude that the MWP was warmer than the CWP at Bette lagoon.