__MAIN_TEXT__

Page 1


Climate Changed Sampler

Climate Changed Sampler

Planet Earth was formed 4.6 billion years ago.

Earth’s climate depends foremost on the amount of energy that comes from the sun.

Its climate is a complex and fluctuating system, varying over the course of time.

That energy level varies according to the sun’s activity and the changing orbit of the planet.

It has determined the history of civilizations. It has helped them survive or destroyed them. The distribution of heat around the globe is determined by a series of factors: the composition of the atmosphere, the layout of the continents, the currents in the ocean . . . all of which interact and form the climate.

12

13


Climate Changed Sampler

Climate Changed Sampler

Planet Earth was formed 4.6 billion years ago.

Earth’s climate depends foremost on the amount of energy that comes from the sun.

Its climate is a complex and fluctuating system, varying over the course of time.

That energy level varies according to the sun’s activity and the changing orbit of the planet.

It has determined the history of civilizations. It has helped them survive or destroyed them. The distribution of heat around the globe is determined by a series of factors: the composition of the atmosphere, the layout of the continents, the currents in the ocean . . . all of which interact and form the climate.

12

13


Climate Changed Sampler

Climate Changed Sampler

During the last million years, the cyclical variations of three astronomical parameters have also influenced the amount of energy that our planet has gotten from the sun, determining Earth’s climate . . .

These cycles are characterized by a succession of cold periods, called glacial periods, which last up to 100,000 years . . .

One, the changes in Earth’s orbit around the sun every 100,000 years. Two, the variations in the axes of our poles on a 60,000-year cycle. And three, the inversion every 13,000 years of which hemisphere is closer to the sun.

. . . and hot periods, called interglacial, which last between 10,000 and 20,000 years.

These three factors have set the stage for the major climatic cycles of the Quaternary period, the geological age we’re now in, which began about two million years ago. This alternation between glacial and interglacial periods has been happening for at least a million years, each time causing major changes to the surface of the planet.

14

15


Climate Changed Sampler

Climate Changed Sampler

During the last million years, the cyclical variations of three astronomical parameters have also influenced the amount of energy that our planet has gotten from the sun, determining Earth’s climate . . .

These cycles are characterized by a succession of cold periods, called glacial periods, which last up to 100,000 years . . .

One, the changes in Earth’s orbit around the sun every 100,000 years. Two, the variations in the axes of our poles on a 60,000-year cycle. And three, the inversion every 13,000 years of which hemisphere is closer to the sun.

. . . and hot periods, called interglacial, which last between 10,000 and 20,000 years.

These three factors have set the stage for the major climatic cycles of the Quaternary period, the geological age we’re now in, which began about two million years ago. This alternation between glacial and interglacial periods has been happening for at least a million years, each time causing major changes to the surface of the planet.

14

15


Climate Changed Sampler Did you know . . . ? There were penguins and seals in the Mediterranean. The sea level was 120 meters lower than it is today. You could walk across the English Channel, and the Bering Strait was frozen right over.

The last glacial period _what we also call the Ice Age _was 20,000 years ago. North America, Greenland, and the Northern European continent were covered in ice sheets over a mile thick.

As the world warms up, the forests and animals reappear. Humans settle down and start to domesticate animals and begin to modify their surroundings.

We’re now in an interglacial epoch called the Holocene, which started 11,000 years ago.

Climate Changed Sampler

But for the last 10,000 years the climate has been stable.

Earth’s climate has changed quite significantly over the course of history, causing the disappearance of certain species.

There have been variations during this period, and they’ve had severe effects on human societies, but they were minor in comparison to the significant changes in the more distant past.

We invent agriculture and animal husbandry.

And one thing is for sure. Compared to the last million years . . .

Between the glacial periods and this warm period, the difference in temperature is only 9oF (5oC).

“. . . the period of human civilization has beEn marked by a stable climate.”

16

17


Climate Changed Sampler Did you know . . . ? There were penguins and seals in the Mediterranean. The sea level was 120 meters lower than it is today. You could walk across the English Channel, and the Bering Strait was frozen right over.

The last glacial period _what we also call the Ice Age _was 20,000 years ago. North America, Greenland, and the Northern European continent were covered in ice sheets over a mile thick.

As the world warms up, the forests and animals reappear. Humans settle down and start to domesticate animals and begin to modify their surroundings.

We’re now in an interglacial epoch called the Holocene, which started 11,000 years ago.

Climate Changed Sampler

But for the last 10,000 years the climate has been stable.

Earth’s climate has changed quite significantly over the course of history, causing the disappearance of certain species.

There have been variations during this period, and they’ve had severe effects on human societies, but they were minor in comparison to the significant changes in the more distant past.

We invent agriculture and animal husbandry.

And one thing is for sure. Compared to the last million years . . .

Between the glacial periods and this warm period, the difference in temperature is only 9oF (5oC).

“. . . the period of human civilization has beEn marked by a stable climate.”

16

17


Climate Changed Sampler

Climate Changed Sampler

The atmosphere around our planet is a very thin shell, no more than a few dozen miles thick, composed mainly of nitrogen and oxygen.

Plate tectonics, for example, modify the distribution of the continents during different geological periods. This alters the ocean currents and the circulation of the atmosphere.

But the climate is a very complex machine, in which factors other than astronomical phenomena are in play.

Certain so-called “internal forcing mechanisms� affect the climate as much as the climate affects them.

The rest, about one part per thousand, is composed of other gases _ a tiny minority but with a major influence on our climate.

Volcanic activity and the resulting dust clouds can cause significant cold periods.

These gases intercept a portion of solar radiation, as well as radiation coming from the planet's surface.

Such as the polar ice caps.

One of the key internal mechanisms is the greenhouse effect.

Their size affects the amount of solar energy that is reflected into the atmosphere.

They are the greenhouse gases: water vapor, carbon dioxide, methane, nitrous oxide, and ozone.

And their size is equally affected by the resulting temperature.

18

19


Climate Changed Sampler

Climate Changed Sampler

The atmosphere around our planet is a very thin shell, no more than a few dozen miles thick, composed mainly of nitrogen and oxygen.

Plate tectonics, for example, modify the distribution of the continents during different geological periods. This alters the ocean currents and the circulation of the atmosphere.

But the climate is a very complex machine, in which factors other than astronomical phenomena are in play.

Certain so-called “internal forcing mechanisms� affect the climate as much as the climate affects them.

The rest, about one part per thousand, is composed of other gases _ a tiny minority but with a major influence on our climate.

Volcanic activity and the resulting dust clouds can cause significant cold periods.

These gases intercept a portion of solar radiation, as well as radiation coming from the planet's surface.

Such as the polar ice caps.

One of the key internal mechanisms is the greenhouse effect.

Their size affects the amount of solar energy that is reflected into the atmosphere.

They are the greenhouse gases: water vapor, carbon dioxide, methane, nitrous oxide, and ozone.

And their size is equally affected by the resulting temperature.

18

19


Climate Changed Sampler

Climate Changed Sampler

The sun’s rays are made up of 10% ultraviolet light, 40% visible light, and 50% near-infrared light (that is, light with a wavelength close to that of visible light).

These rays are almost all intercepted by the greenhouse gases . . . . . . which trap heat in the lower layers of the atmosphere.

When sunlight reaches the atmosphere, the greenhouse gases reflect 30% of those rays right back into space.

Once heated, Earth’s surface sends back radiation in the farinfrared wavelength _ light that is the farthest from the spectrum of visible light. Another 20% of solar radiation warms the atmosphere. The rest of the radiation, about 50%, directly heats the surface of the planet, both the oceans and the continents.

20

21


Climate Changed Sampler

Climate Changed Sampler

The sun’s rays are made up of 10% ultraviolet light, 40% visible light, and 50% near-infrared light (that is, light with a wavelength close to that of visible light).

These rays are almost all intercepted by the greenhouse gases . . . . . . which trap heat in the lower layers of the atmosphere.

When sunlight reaches the atmosphere, the greenhouse gases reflect 30% of those rays right back into space.

Once heated, Earth’s surface sends back radiation in the farinfrared wavelength _ light that is the farthest from the spectrum of visible light. Another 20% of solar radiation warms the atmosphere. The rest of the radiation, about 50%, directly heats the surface of the planet, both the oceans and the continents.

20

21


Climate Changed Sampler

The greEnhouse efFect is a natural phenomenon, trapPing the heat in the lower layer of the atmosphere and alLowing the planet to maintain a range of mild temperatures, an average of about 60oF (15oC). This makes life on Earth posSible.

Without the greenhouse effect, the average temperature on the surface of the planet would be 0oF (-18oC). There would be no liquid water. Life would not exist.

On Mars, where the atmosphere is very thin, the average temperature is -81oF (-63 oC).

Climate Changed Sampler

Examining polar ice core samples, which allows us to reconstruct the atmosphere of the distant past, confirms how sensitive the climate is to the slightest alteration.

In 1987, Jean Jouzel and his colleagues demonstrated that there is a direct link between major climate cycles and the evolution of the concentration of greenhouse gases in the atmosphere.

Multiple factors are constantly interacting, and any change to any part of the system throws off the whole equilibrium.

Over the last million years, the levels of CO2 and methane have evolved in tandem with variations in the climate, influencing each other.

During the warming that follows glacial periods, carbon dioxide (CO2) levels rise.

On the other hand, it’s well over 750 oF (400 oC) on the surface of Venus, where the atmosphere is 95% carbon dioxide.

Gases that are present in small quantities in the atmosphere largely regulate the balance of safe temperatures on our planet.

The dependence on these minor elements is what makes our climate so extremely vulnerable to change.

22

This rise increases the greenhouse effect and, thus, the average temperature.

Of the 9oF (5oC) temperature difference between the last glacial period and now, about 3.5oF (2oC) can be attributed to interactions between the climate and greenhouse gases.

And even if the position of Earth as it travels around the sun is the metronome of the large variations of the Quaternary period, the greenhouse effect has followed and amplified these cycles.

23


Climate Changed Sampler

The greEnhouse efFect is a natural phenomenon, trapPing the heat in the lower layer of the atmosphere and alLowing the planet to maintain a range of mild temperatures, an average of about 60oF (15oC). This makes life on Earth posSible.

Without the greenhouse effect, the average temperature on the surface of the planet would be 0oF (-18oC). There would be no liquid water. Life would not exist.

On Mars, where the atmosphere is very thin, the average temperature is -81oF (-63 oC).

Climate Changed Sampler

Examining polar ice core samples, which allows us to reconstruct the atmosphere of the distant past, confirms how sensitive the climate is to the slightest alteration.

In 1987, Jean Jouzel and his colleagues demonstrated that there is a direct link between major climate cycles and the evolution of the concentration of greenhouse gases in the atmosphere.

Multiple factors are constantly interacting, and any change to any part of the system throws off the whole equilibrium.

Over the last million years, the levels of CO2 and methane have evolved in tandem with variations in the climate, influencing each other.

During the warming that follows glacial periods, carbon dioxide (CO2) levels rise.

On the other hand, it’s well over 750 oF (400 oC) on the surface of Venus, where the atmosphere is 95% carbon dioxide.

Gases that are present in small quantities in the atmosphere largely regulate the balance of safe temperatures on our planet.

The dependence on these minor elements is what makes our climate so extremely vulnerable to change.

22

This rise increases the greenhouse effect and, thus, the average temperature.

Of the 9oF (5oC) temperature difference between the last glacial period and now, about 3.5oF (2oC) can be attributed to interactions between the climate and greenhouse gases.

And even if the position of Earth as it travels around the sun is the metronome of the large variations of the Quaternary period, the greenhouse effect has followed and amplified these cycles.

23


Climate Changed Sampler

Climate Changed Sampler

Throughout the Quaternary period, the concentrations of greenhouse gases in Earth’s atmosphere have echoed the climatic changes. And they always stayed within limited values, never exceeding a certain ceiling. Since the beginning of the Industrial Revolution, the quantity of greenhouse gases in the atmosphere has increased in a sudden leap.

In a little less than two centuries, the concentration of CO2 has gone up 30%. Years ago

Analysis of air bubbles in polar ice shows that, for hundreds of thousands of years, the chemical composition of our atmosphere remained stable.

The amount of methane has doubled.

And new gases have made an appearance. For 800,000 years, the CO2 level never exceeded 300 PPM (parts per million by volume).

Until 1850 . . .

24

25


Climate Changed Sampler

Climate Changed Sampler

Throughout the Quaternary period, the concentrations of greenhouse gases in Earth’s atmosphere have echoed the climatic changes. And they always stayed within limited values, never exceeding a certain ceiling. Since the beginning of the Industrial Revolution, the quantity of greenhouse gases in the atmosphere has increased in a sudden leap.

In a little less than two centuries, the concentration of CO2 has gone up 30%. Years ago

Analysis of air bubbles in polar ice shows that, for hundreds of thousands of years, the chemical composition of our atmosphere remained stable.

The amount of methane has doubled.

And new gases have made an appearance. For 800,000 years, the CO2 level never exceeded 300 PPM (parts per million by volume).

Until 1850 . . .

24

25

Profile for Abrams&ChronicleBooks

Climate Changed by Philippe Squarzoni  

Based on the analysis of the Intergovernmental Panel on Climate Change (IPCC), but seen through the perspective of everyman journalist Phili...

Climate Changed by Philippe Squarzoni  

Based on the analysis of the Intergovernmental Panel on Climate Change (IPCC), but seen through the perspective of everyman journalist Phili...

Advertisement