Humans forcing changes to Earth havebegun a new geologic epoch: study

Isis Temple, named after the ancient Egyptian goddess, is a geologic formation at the Grand Canyon in Arizona. The

different layers of rock show the periods of geological change. Photo: Wikimedia Commons

Over the course of its long history, the Earth has undergone enormous changes.

Continents have drifted, species have flourished and gone extinct, and ice ages have

come and gone.

Geologists study the history of the Earth by examining buried layers of rock and soil, called

"strata." These strata contain clues that tell the story of how the Earth has changed over

time.

Earth's Evolving Timeline

Geologists break that story up into time periods that describe the different phases that the

Earth has gone through. In this way, they are like historians who divide history into periods

such as The Middle Ages and The Renaissance. To divide the Earth's history, scientists

use a system called the geologic timescale. It consists of several different categories.

Eons are long periods of time that are made up of eras. Eras consist of periods, which are

made up of epochs, which are made up of ages.

By Scientific American, adapted by Newsela staff on 01.15.16

Word Count 947

Scientists created the timescale based on how the Earth has changed over time, with each

era or epoch set apart from the next, but with some significant global change. We are

currently in the Holocene epoch, which began about 11,750 years ago when the most

recent ice age began to melt, bringing about a series of massive geologic changes that

shaped the Earth as we know it.

The Planet Continues To Mature

Geologists are debating whether we are now entering a new epoch. Some believe that

human beings have had such a dramatic effect on the planet in recent years that we have

changed it in a geologically significant way. They call the new epoch, brought on by

human activity, the Anthropocene.

"This Anthropocene signal is global, it is sharp and all the signs are big," argues geologist

Jan Zalasiewicz of Leicester University in England. He is the scientist in charge of the

group tasked with making a recommendation about whether to declare a new epoch.

Twenty-four members of that working group, including Zalasiewicz, have just published a

report, summarizing the evidence for the Anthropocene, in the journal Science.

They determined that major changes are taking place on Earth due to human activity. "A

real geological phenomenon is taking place, it is still going on. In many respects, it's

accelerating even as we speak," Zalasiewicz says.

Growing Population, Consumption, Technology

As we burn more and more fossil fuels like oil and coal, humans are adding carbon dioxide

to the atmosphere at ever increasing rates. The added carbon dioxide is causing global

temperatures to rise, which may in turn lead to enormous environmental changes.

Meanwhile, humans are reshaping the Earth on a rapidly expanding scale.

New technology, the increasing human population, and our growing consumption of

Earth's resources, from crops to metals, have expanded the impacts humanity has made.

These trends have been rapidly increasing since 1950 or so, a turning point some have

dubbed the "Great Acceleration."

Humans have created new materials, altering the planet's makeup, such as copper alloys

or plastics that last for hundreds of years. The amount of plastic produced each year

weighs more than all 7 billion people on the planet combined, and enough concrete has

been made by now to encase the entire world. These human-made products are altering

the material make-up of the planet.

As a result of all of this human activity, Zalasiewicz and his co-authors argue that the Earth

now looks and functions differently. They see these changes as so dramatic that they

believe that a new epoch is upon us, one that is distinct from the Holocene.

Pinning Down The Latest Epoch

Key questions remain, however. If the Earth has already entered into a new epoch, when

did that new epoch begin? This question comes down to when the really significant

geologic changes started. Perhaps the epoch began thousands of years ago with human

farming, or the widespread burning of landscapes by ancient ancestors, or perhaps it

began with more recent technological and industrial advances.

Some, including Zalasiewicz, have proposed a very precise start date for the

Anthropocene: July 16, 1945, the date of the first test of an atomic bomb at Alamogordo,

New Mexico. This marked the beginning of the spread of rare radioactive elements like

plutonium around the globe, which altered the planet in a way that will be detectable for at

least 100,000 years.

Scientist hope that more research will allow them to better understand the geologic impact

of human history. For example, geologists would like to examine the strata forming off the

California coast to look for plutonium and soot, which would allow them to more closely link

geological changes with human events. "That is science that will need some organization

and some money," Zalasiewicz said.

Some Scientists Say "Not So Fast"

Not everyone agrees that we are entering into a new epoch at all, however. Even

among Zalasiewicz's team, some disagreed with the idea of the Anthropocene. "Many find

it difficult to accept that an epoch that is so short in duration can be adequately

recognized," said Colin Waters of the British Geological Survey, lead author of the new

analysis.

Some scientists doubt whether human beings have really changed the planet enough to

warrant proposing a new epoch, while others think that it is too soon to tell, considering

that big changes like mass extinctions and the impacts of climate change have yet to

occur.

For now, thinking on the Anthropocene remains divided. With the release of his new

study, Zalasiewicz is looking to promote further discussion among his fellow scientists. "We

are putting together ideas and then hoping to gather responses from people who can give

us some sensible feedback from which we can eventually develop our formal

recommendation," he said.

Quiz

1 Which sentence from the article BEST develops the central idea that humans are causing the

planet to change in major ways?

(A) These trends have been rapidly increasing since 1950 or so, a turning point

some have dubbed the "Great Acceleration."

(B) Humans have created new materials, altering the planet's makeup, such as

copper alloys or plastics that last for hundreds of years.

(C) As a result of all of this human activity, Zalasiewicz and his co-authors argue

that the Earth now looks and functions differently.

(D) Scientist hope that more research will allow them to better understand the

geologic impact of human history.

2 Which answer choice provides the most accurate summary of the article?

(A) Scientists hope to raise funds to research geological changes that may

prove the start of the new epoch.

(B) There is major disagreement among scientists about when the most recent

epoch began, and how it was caused.

(C) Many scientists believe the Earth has entered a new epoch due to the

effects of the first atomic bomb.

(D) Some scientists believe the Earth has entered a new epoch due mainly to

human activity, while others disagree.

3 Based on the article, which of the following conclusions can be drawn?

(A) Zalasiewicz believes the Earth is currently experiencing significant global

change.

(B) Most of the major changes caused by human activity are already apparent.

(C) Scientists will come to an agreement about when the new epoch began

based on Zalasiewicz's report.

(D) Technology plays just a small role in the overall changes that have

contributed to the beginning of the new epoch.

4 Which section of the article BEST develops the idea that the planet has experienced major

shifts in the very recent past?

(A) "The Planet Continues To Mature"

(B) "Pinning Down The Latest Epoch"

(C) "Growing Population, Consumption, Technology"

(D) "Some Scientists Say Not So Fast"

Answer Key

1 Which sentence from the article BEST develops the central idea that humans are causing the

planet to change in major ways?

(A) These trends have been rapidly increasing since 1950 or so, a turning point

some have dubbed the "Great Acceleration."

(B) Humans have created new materials, altering the planet's makeup, such

as copper alloys or plastics that last for hundreds of years.

(C) As a result of all of this human activity, Zalasiewicz and his co-authors argue

that the Earth now looks and functions differently.

(D) Scientist hope that more research will allow them to better understand the

geologic impact of human history.

2 Which answer choice provides the most accurate summary of the article?

(A) Scientists hope to raise funds to research geological changes that may

prove the start of the new epoch.

(B) There is major disagreement among scientists about when the most recent

epoch began, and how it was caused.

(C) Many scientists believe the Earth has entered a new epoch due to the

effects of the first atomic bomb.

(D) Some scientists believe the Earth has entered a new epoch due mainly

to human activity, while others disagree.

3 Based on the article, which of the following conclusions can be drawn?

(A) Zalasiewicz believes the Earth is currently experiencing significant

global change.

(B) Most of the major changes caused by human activity are already apparent.

(C) Scientists will come to an agreement about when the new epoch began

based on Zalasiewicz's report.

(D) Technology plays just a small role in the overall changes that have

contributed to the beginning of the new epoch.

4 Which section of the article BEST develops the idea that the planet has experienced major

shifts in the very recent past?

(A) "The Planet Continues To Mature"

(B) "Pinning Down The Latest Epoch"

(C) "Growing Population, Consumption, Technology"

(D) "Some Scientists Say Not So Fast"