10.3 Origin of Recent climate change: The green house world around the North Atlantic - Michael Houmark-Nielsen

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Из курса от партнера University of Copenhagen

Origins - Formation of the Universe, Solar System, Earth and Life

355 оценки

University of Copenhagen

Origins - Formation of the Universe, Solar System, Earth and Life

355 оценки

The Origins course tracks the origin of all things – from the Big Bang to the origin of the Solar System and the Earth. The course follows the evolution of life on our planet through deep geological time to present life forms.

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Origin of Recent Climate Change / The Molecular Clock

In module 10, we will tell you about two very different topics – recent climate changes and the molecular clock. Michael Houmark will tell you about the changes in global climate over the past 50 million years. During this period the warm temperatures in the Eocene were gradually replaced by the much lower, present day temperatures. Michael will show you how much better records of sea level, temperature, CO2, volcanic activity, and continental drift in the recent past allow us to piece together a detailed picture of these dramatic changes in Earth’s climate. Our records of recent climate change also allow us to better understand the processes controlling the climate on short, medium, and long time scales. Ole Seberg will tell you about the molecular clock. This is a new technique, which has significantly improved our understanding of the evolution of life on our planet. Looking at molecular data of present species, we can not only determine how closely the species are related to each other, we can also estimate the age of their common ancestors.

10.1 Origin of Recent climate change: Earth today and yesterday - Michael Houmark-Nielsen 9:54

10.2 Origin of Recent climate change: The changing face of the Earth - Michael Houmark-Nielsen4:33

10.3 Origin of Recent climate change: The green house world around the North Atlantic - Michael Houmark-Nielsen 4:02

10.4 Origin of Recent climate change: Drifting towards the ice house - Michael Houmark-Nielsen3:58

10.5 Origin of Recent climate change: On the door step of the ice house - Michael Houmark-Nielsen 3:09

10.6 Origin of Recent climate change: The ice house world of the Pleistocene - Michael Houmark-Nielsen7:33

10.7 The Molecular Clock: Discovery of the Molecular Clock Part 1 - Ole Seberg 16:02

10.8 The Molecular Clock: Phylogeny and Molecular Data Part 2 - Ole Seberg 16:48

10.9 The Molecular Clock: Explanations Part 3 - Ole Seberg15:40

Познакомьтесь с преподавателями

Henning Haack
Associate Professor
Natural History Museum
James Connelly
Professor
Natural History Museum of Denmark
Vivi Vajda
Professor
Department of Geology, Lund University
Jon Fjeldså
Professor, Curator
Thomas Gilbert
Professor
Michael Houmark-Nielsen
Associate Professor
Natural History Museum of Denmark
Bent Erik Kramer Lindow
Curator
Natural History Museum of Denmark
Gilles Guy Roger Cuny
Associate Professor
Natural History Museum of Denmark
Ole Seberg
Associate Professor
Natural History Museum of Denmark
Gitte Petersen
Associate Professor
Natural History Museum of Denmark
Tais Wittchen Dahl
Assistant Professor of Geobiology
Arne Thorshøj Nielsen
Associate Professor
Natural History Museum of Copenhagen
Martin Vinther Sørensen
Associate Professor, Curator
Natural History Museum of Denmark
Svend Stouge
Associate Professor
Natural History Museum of Denmark
Danny Eibye Jacobsen
Associate Professor, Curator
Natural History Museum of Denmark
Jan Audun Rasmussen
Associate Professor
Natural History Museum of Denmark
Emily Catherine Pope
Assistant professor
Natural History Museum of Denmark

[MUSIC]

Between 18 and 15 million years ago, the configuration of continents and

oceans in a global perspective was much different than from today.

Antarctic and Australia were still close to each other while India and

Africa was on a collision course with Eurasia, closing the formitative sea.

The two American continents were separated by a wide strait linking the Pacific,

the Atlantic and the Tethys oceans together

which produced dominant sea surface currents circulating around the equator.

Present day Arctic Greenland just [INAUDIBLE] around the emerging North Sea

of Northwestern Europe had roughly taken their latitude position

in the global plate tectonic puzzle by the beginning of the late Cretaceous and

the early Cenozoic.

The age of the ocean floor can be dated by radiometric methods and

paleomagnetic correlation.

Rifting and eventually opening of the central

Atlantic Ocean commenced in the cretaceous and continued northward.

In the Paleozoic and Eocene, huge volumes of basaltic lava and

ash was extruding from volcanic ridges fed by rising magma

in the region between east Greenland and Scotland.

Eventually, shallow seas drowned the former land bridge between Europe

and Greenland.

At this time, continents were worn down and had low relief and

the North Sea region received only little and fine grain terrestrial material.

To the south, the collision between Europe and

Africa met the closure of the sea and the rising of the Alps.

The natural history museum in Copenhagen exhibits

some extraordinary fossils from central west Greenland,

indicating that tropical to subtropical climate ruled this far north.

Estimates of the paleo latitude for the region suggests

That the precision was just 10 degrees more to south than the present latitude or

about 70 degrees north.

In the cliffs of the peninsular, of the giant bivalve called

have been found among other both demanding marine fossils living in coastal waters.

In northwest Europe, deposits of the Paleocene Eocene from the North Sea

region are exposed in glacially disturbed cliff sites in northern Denmark.

Fine grain white diatomite composed of minute skeletons of marine silica

algae is interbedded with black layers of volcanic ash

deposited on the sea floor from wind blown plumes

by northwesterly winds from the powerful eruptions of the opening north Atlantic.

The shallow sea was surrounded by low relief land masses dominated by

subtropical biota.

The marine microfauna resembles that found in modern open subtropical waters.

The diatomite is especially rich in terrestrial micro fossils, plants,

insects and higher animals which were rafted, floated or blown to sea, and

their biology indicates that most species originated

in subtropical environments with seasonal changes.

We must, therefore, conclude that the subtropical climate indicated by the early

fossil record from these sites indicate that the warm conditions here was

not caused by a more southerly location similar to modern subtropical regions.

But former climate was in fact much warmer in higher latitudes than today.

[MUSIC]

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