Name: ancient clues to climate change
Uploaded: 2019-03-11T09:21:43.000Z
Duration: 1 min 50 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

ecosystems-interactions-energy-and-dynamics

Ecosystems- Interactions, Energy, and Dynamics

LS.Bio.5.2

Global Climate Change

- [Narratore] La Terra
ha attraversato periodi

di riscaldamento e raffreddamento
lungo tutta la sua storia.

Tuttavia negli ultimi secoli

c'è stato un drastico incremento
nelle temperature globali

al di fuori dei normali cicli della Terra.

Il riscaldamento accade quando
i gas serra in atmosfera

come l'anidride carbonica,
restano intrappolati

tra la superficie e lo strato di ozono.

L'anidride carbonica può
assorbire l'energia solare

nelle lunghezze d'onda
del lontano infrarosso,

impedendogli di tornare
nello spazio esterno,

quindi incrementando la
temperatura atmosferica.

Nonostante questo sia un processo naturale

chiamato effetto serra,

il netto incremento nella
quantità di anidride carbonica

presente nell'atmosfera terrestre,

causato dalla combustione di
carbone e petrolio, non lo è.

I risultati di questo
incremento di temperatura

possono essere osservati
a livello globale.

Per esempio nell'Artico

si stanno sciogliendo le calotte polari,

determinando l'aumento
del livello degli oceani

e la sommersione delle isole.

Ciò non solo minaccia le città costiere,

ma può anche aumentare l'insorgenza

di eventi meteorologici estremi,

come la siccità, gli
uragani e le forti tempeste.

Inoltre le migrazioni e gli accoppiamenti

di molti animali avvengono
prima durante l'anno

rispetto a qualche decade fa.

E la dimensione degli areali
delle specie sta diminuendo.

Con il riconoscimento
del riscaldamento globale

da parte dei più scettici,

l'aumento delle pratiche eco-sostenibili

da parte delle industrie

potrebbe fornire l'opportunità

di capovolgere l'impatto dell'uomo

e aiutare a evitare le gravi conseguenze

del cambiamento climatico globale.

Castellano, E., S. Becagli, M. Hansson, M. Hutterli, J. R. Petit, M. R. Rampino, M. Severi, J. P. Steffensen, R. Traversi e R. Udisti. "Storia vulcanica dell'Olocene registrata nella stratigrafia del solfato del progetto europeo per il carotaggio del ghiaccio nel nucleo di ghiaccio della cupola antartica C (EDC96)." Journal of Geophysical Research: Atmospheres 110, n. D6 (2005). [<a href="https://doi.org/10.1029/2004JD005259" target="__blank">Sorgente</a>]

Yang, Bao, Chun Qin, Jianglin Wang, Minhui He, Thomas M. Melvin, Timothy J. Osborn e Keith R. Briffa. "Un record di 3.500 anni di precipitazioni annuali sugli anelli degli alberi sull'altopiano tibetano nord-orientale". Atti dell'Accademia Nazionale delle Scienze 111, n. 8 (25 febbraio 2014): 2903–8. [<a href="https://doi.org/10.1073/pnas.1319238111" target="__blank">Sorgente</a>]

cambiamento climatico globale

Nel corso dei suoi 4,5 miliardi di dollari di storia, la Terra ha vissuto periodi di riscaldamento e raffreddamento. Tuttavia, l'attuale drastico aumento delle temperature globali è ben al di fuori delle norme cicliche della Terra, e le prove del cambiamento climatico globale causato dall'uomo sono convincenti. La paleoclimatologia, lo studio delle antiche condizioni climatiche, fornisce ampie prove del cambiamento climatico globale causato dall'uomo confrontando le condizioni recenti con quelle del passato.

<h4>Passati periodi di riscaldamento e raffreddamento</h4>

Solo negli ultimi 650.000 anni ci sono stati sette cicli di avanzamento glaciale e di ritiro. Più di 11.000 anni fa, l'era glaciale più recente si è bruscamente conclusa, segnando l'inizio della nostra era climatica moderna, l'epoca geologica dell'Olocene. La maggior parte dei cambiamenti climatici storici sono associati a piccole variazioni nell'orbita terrestre che hanno cambiato la quantità di radiazione solare ricevuta dalla Terra.

<h4>Paleoclimatologia</h4>

La paleoclimatologia è lo studio delle condizioni climatiche e delle loro cause ed effetti in tutto il passato geologico della Terra. I paleoclimatologi utilizzano una varietà di metodi scientifici per dedurre le condizioni passate del clima e del sistema atmosferico terrestre.

<h4>Dati del nucleo di ghiaccio</h4>

I campioni di carote di ghiaccio prelevati da spessi ghiacciai montani e calotte polari possono rivelare informazioni sul cambiamento climatico globale. Le pause stagionali nell'accumulo di ghiaccio possono portare a strati osservabili in carote di ghiaccio. Questi strati possono essere utilizzati per stabilire una cronologia, con gli strati più bassi sono i più antichi. I ricercatori possono quindi analizzare le proprietà del ghiaccio e del materiale intrappolato al suo interno (ad esempio, bolle d'aria e rapporti di isotopi di ossigeno e idrogeno) per ricostruire il clima antico della Terra. Il progetto europeo per Il ghiaccio Coring in Antartide ha analizzato la cenere vulcanica intrappolata nei nuclei di ghiaccio dall'Antartide per fornire una registrazione dettagliata della storia vulcanica dell'Olocene. Questo record rivelò 96 eruzioni durante l'Olocene, con 33 di quelle eruzioni che si verificarono negli ultimi 2.000 anni.

<h4>Dendroclimatologia</h4>

Gli scienziati possono anche studiare il clima passato esaminando gli anelli annuali degli alberi, un campo chiamato dendroclimatologia. Essenzialmente, gli anelli degli alberi sono più larghi in condizioni favorevoli e più stretti durante i periodi difficili. Gli anelli degli alberi possono essere datati con precisione abbinando anelli da un campione all'altro, anche campioni provenienti da scavi archeologici. Anche se la dendroclimatologia ha limitazioni, gli anelli degli alberi sono proxy climatici utili che possono essere utilizzati per creare record climatici ad alta risoluzione per specifiche località geografiche.

Cambiamento Climatico Globale

Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global ...

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ancient clues to climate change

Ancient climate clues help scientists track global climate change. Paleoclimatology is the study of climate conditions in Earth’s past and the causes and effects behind them. By comparing recent climate patterns with older records, researchers can find strong evidence for human-caused warming.

Earth’s climate has changed many times over its 4.5 billion year history. In the last 650,000 years, there have been seven cycles of glacial advance and retreat. The most recent ice age ended more than 11,000 years ago and began the Holocene, the modern climate era. Many earlier changes were linked to small shifts in Earth’s orbit that altered the amount of solar radiation reaching the planet.

Paleoclimatologists use several scientific methods to study the past climate and atmosphere. One major source is ice core data from thick mountain glaciers and polar ice sheets. Seasonal pauses in ice buildup create layers in the ice, and the lowest layers are the oldest. Scientists can study the ice itself and the trapped material inside it, such as air bubbles and ratios of oxygen and hydrogen isotopes, to reconstruct ancient climate conditions.

Ice cores can also preserve volcanic ash. The European Project for Ice Coring in Antarctica used ash trapped in Antarctic ice cores to build a detailed record of Holocene volcanic history. That record showed 96 eruptions during the Holocene, including 33 eruptions in the last 2,000 years. Another useful climate proxy is tree rings. Dendroclimatology, the study of annual tree rings, shows that rings are wider in favorable conditions and narrower in harsh ones. Tree rings can be matched and dated across samples, even from archaeological digs, and they help create high-resolution climate records for specific places, although the method has limits.

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Ancient Clues to Climate Change

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