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 Earth's Climate History

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ΔημοσίευσηΘέμα: Earth's Climate History   03.11.10 13:09



Fiery Birth: Hadean Era
Time: 4.5 to 3.8 billion years ago


A supernova – the explosion of a dying star – leads to the formation of the solar system.

The sun starts to provide light and heat for a liquid and fiery Earth.

When temperatures finally cool down, the first ocean appears.

(Photo: Shutterstock)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:12



Spark of Life: Archaean Era
Time: 3.8 to 2.5 billion years ago


Solid rock forms on Earth.

Simple life develops and the first bacteria add oxygen to a still toxic atmosphere.

The sun only has 75 percent of today’s energy output but an archaic greenhouse effect based on methane prevents an ice age.

(Photo: Shutterstock)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:15



Oxygen Earth: Proterozoic Era
Time: 2500 to 500 million years ago


Photosynthetic algae prosper and enrich the planet’s atmosphere with oxygen.

Oxidation turns rocks like these found in Texas’ Palo Duro Canyon bright red.

Many of the first anaerobic life forms vanish. Several periods of intensive glaciations, probably even a completely frozen 'Snowball' Earth, occur.

(Photo: Public Domain)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:16



Life Explodes: Paleozoic Era
Time: 500 to 250 million years ago


Earth’s core cooled to today’s temperature levels.

The two primary landmasses, Laurussia and Gondwana, wander across the North and South Pole where they receive little solar energy; ice sheets grow and shrink.

The proliferation of photosynthetic organisms makes the air breathable.

Life explodes.

(Photo: Wikimedia Commons, Pierre Dèzes, http://en.wikipedia.org/wiki/File:290_global.gif)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:20



Jurassic Park: Mesozoic Era
Time: 250 to 65 million years ago


Earth’s climate is dry and highly seasonal. Only coastal regions experience stable temperatures.

Humidity increases when the supercontinent Gondwana breaks up into smaller units creating more coastal regions.

Temperatures are about 10 degrees Celsius higher than today and similar everywhere from the poles to the equator.

The dinosaur population flourishes.

(Photo: Reuters)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:22



Mammals Master Earth: Cenozoic Era
Time: from 65 million years ago


An asteroid the size of the Isle of Wight crashes into Mexico and ends the reign of the dinosaurs.

The impact raises dust and soot that blankets the entire planet and radically changes the climate for decades.

Birds and mammals replace the dinosaurs.

(Photo: Reuters)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:24



Tropical Paradise: Paleogene Period
Time: 65 to 23 million years ago


Ocean temperatures are about 10 to 15 degrees Celsius higher than today.

Palm trees are growing in Greenland and Patagonia.

The Indian tectonic plate collides with the Asian plate, forming the Himalayas.

This sparks a new period of glaciation and Earth starts to cool down again.

(Photo: Shutterstock)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:28



First Freeze: Miocene Epoch
Time: 23 to 5.3 million years ago


The continents take their current positions.

Antarctica becomes isolated from South America and is separated from warm ocean waters.

Its forests are slowly replaced by glaciers.

The cooling trend leads to increasing aridity.

(Photo: Reuters)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:30



Cooling Down: Pliocene Epoch
Time: 5.3 to 2.6 million years ago


Climatic patterns resemble what we experience today but global surface temperatures are still two to three degrees Celsius higher.

The Arctic region is significantly warmer and with less ice at the poles, sea levels are probably about 25 to 30 meters higher than at present.

Grasslands and savannas slowly replace rainforests.

(Photo: Shutterstock)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:32



Ice Ages: Pleistocene epoch
Time: 2.5 million to 12,000 years ago


Earth’s orbit around the sun changes and the planet receives less solar energy.

Glaciers advance from the North Pole and large parts of North America, Europe, and Asia are covered by huge ice sheets.

Short warming spells drive the ice back but ice ages dominate.

During the cold peaks, average global temperatures are about four to five degrees Celsius below current levels.

(Photo: Ice age Earth at glacial maximum. Based on: "Ice age terrestrial carbon changes revisited" by Thomas J. Crowley CCSA 3.0)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:34



Gulf Stream Collapses: Younger Dryas
Time: 13,000 to 11,500 years ago


The end of the Pleistocene is marked by a period of sudden cooling.

The name derives from the alpine wildflower Dryas octopetala, which was found in ice cores from the era.

Europe is particularly affected and temperatures in parts of Greenland are 15 degrees Celsius lower than today.

Paradoxically, the cooling probably stems from prior warming that brought a huge amount of warm fresh water into the North Atlantic thereby weakening the Gulf Stream. (Photo: Reuters)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:36



Great Thaw: Holocene (2/7)
Time: from 12,000 years ago


We are living in the Holocene epoch, a short interglacial warming spell.

Melting ice sheets and glaciers have caused sea levels to rise by 20 to 35 meters.

Regions that were held down by the weight of the glaciers have risen up to 200 meters.

Glacial retreat formed the Baltic Sea. Within this epoch, there have been several short periods of warming and cooling.

(Photo: NASA)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:37



Ups and Downs
Time: 3,000 B.C to 850 A.D.


Cooling and warming periods follow one another closely.

A 1000-year freeze until 2000 B.C. causes a large drop in sea levels and islands like the Bahamas appear.

From then until 750 B.C. warming and cooling periods alternate.

Ice sheets shrink and grow with sea levels dropping two to three meters below today’s levels.

During the time of the Roman Empire, a cold snap causes the Nile River and the Black Sea to freeze.

(Photo: Reuters)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:39



Medieval Warm Period
Time: 900 to 1200


During the warmest period since the beginning of the Holocene, the Vikings settle in Greenland and Iceland.

The Medieval Warm Period was followed by extreme weather.

Between 1276 and 1299, the American southwest was haunted by severe drought.

Elsewhere, historic records document droughts, floods, and dramatic climate fluctuations until 1400.

(Photo: Reuters)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:41



Little Ice Age
Time: 1550 to 1850


Global temperatures are colder than ever before in the Holocene.

The average temperature in the northern hemisphere is about one degree Celsius lower than today.

In 1753, about a quarter of Iceland’s population dies because of crop failure and famine.

Newspapers in New England call 1816 the year without summer.

(Photo: The frozen river Thames in 1677, Wikimedia)


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ΔημοσίευσηΘέμα: Απ: Earth's Climate History   03.11.10 13:42



Global Warming: The Anthropocene
Time: 1850 to present day


Earth experiences general warming, coinciding with the Industrial Revolution.

Between 1980 and 2006 temperatures are about 0.20 to 0.63 degrees Celsius higher than in mid-century.

The scientific consensus is that these warmer temperatures are largely man-made—anthropogenic.

Some scientists claim that the Holocene has ended and the Anthropocene has begun.

Humanity has begun to manipulate the climate.

(Photo: Reuters)


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Earth's Climate History
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