From the Pleistocene to the "Anthropocene"

Look at the following graph of Earth's temperature during the Pleistocene period, the time when most ancient and certainly modern humans came about. What characterizes the Pleistocene? How did it end? The next period, in which we currently live is called the Holocene. What difference do you notice between the Pleistocene and the Holocene? what do you think are the implications for people?

Paleotemperature graph from Wikipedia

Now let's look at the time when humans started migrating out of Africa and populating all continents:

From Khan Academy

In this radio segment, listen to the introduction of a new concept, the "Anthropocene", and take notes about key concepts or questions you have about it:

 When did humans start shaping Earth's fate? from National Public Radio

When did the "Anthropocene" really begin? How did the first Homo Sapiens or modern humans interact with their environment? How did they change it?

What Killed the Mega Beasts? Discovery Channel

Top 10 animals hunted to extinction in a more recent past.

Earth's Timeline

Students have been working in groups to research data on the following subjects relating to the history of the biosphere: temperature, composition of the atmosphere, plate tectonic, paleobiology, geological periods, crucible events. They then incorporated them into a timeline, showing the relationship between geology, biology, earth chemistry and sometimes even extra terrestrial influences (gravitational pull, asteroid strikes, etc.).

On this 4.5 meters timeline representing the 4.5 billion years of Earth's history, 40 000 years of human history was represented by a single vertical line, the width of a human hair. This will be our next object of study.

Perspective: the KT event

As we continue to learn about what's influenced climate and life over the entire span of Earth's history, we discussed the following graph depicting Earth's temperature over the past 500 million years, starting with the Cambrian period (a time when complex life forms finally emerged on Earth, after it recovered from the dramatic "Snowball Earth" ice age discussed previously):

Paleotemperature graph from Wikipedia

In particular, we looked at sudden and dramatic temperature shifts and tried to figure out what prompted them. Did the overabundance of oxygen in the atmosphere at the end of the Carboniferous Period generate the Permian ice age? Were the Siberian Traps volcanic eruptions at the origin of the dramatic warming that followed? What was the effect of the KT asteroid impact on climate?

We also learned about the Cretaceous Tertiary (KT) event, which brought about the demise of dinosaurs by watching the fourth and last episode of Prehistoric Disasters: Asteroid strike from the Discovery Channel.

Watch this compilation of videos of the Chelyabinsk meteor, which hit the Ural region in Russia three years ago. It is estimated that it measured 20 meters in diameter when it entered Earth's atmosphere: very small in comparison to the 10 kilometers-wide asteroid that struck the earth during the KT event.

Perspective: the Siberian Traps

 picture from BBC.com

- What happened 250 Million years ago during the million year long volcanic eruption of the Siberian Traps? What gases came out of volcanoes, and what was their effects on the composition of the atmosphere and of the oceans? What chain reaction led to sudden global warming? What happened to life under those extreme conditions?

We'll answer those questions by watching and discussing the third episode of Prehistoric Disasters: Planet of Fire from the Discovery Channel.

Read the article on BBC Earth

Action: habitat restoration

In this lesson we took a first step toward intentionally designing our campus as a habitat garden for beneficial species. We learned about the iconic North American Monarch butterfly, about the reasons for its recent population decline, and planted Milkweed on campus in order to create a Monarch way station right here at MPH, thereby linking our campus to the Monarch migration corridor.

 AD is extracting seeds from a Milkweed pod.

Students are planting their seeds on the sunny hill overlooking the lower soccer field.

The next day, students are planting Milkweed along the nature trail.

Thank you to Ms. Cousins, who provided us with Milkweed pods for this experiment.

Perspective: Snowball Earth

 Snowball Earth, picture from NASA

- What triggers an ice age, and a period of warming? What happened 650 million years ago, when the earth became "snowball earth", covered in ice from the poles to the equator? How did it impact life? Was it a factor in the rise of multi-cellular organisms, and the ensuing Cambrian explosion?

We'll answer those questions by watching and discussing the second episode of Prehistoric Disasters: Snowball Earth from the Discovery Channel.

Public Speaking and Self-Awareness

Today students presented the natural phenomena they observed during our last class and researched at home. 

We started by reminiscing about the nature good and bad presentations we had witnessed in the past in order to get a sense of what specific techniques to shoot for in a presentation, and what to avoid.

As groups were presenting, every student took notes on it in order to give feedback to the presenters. When all groups were done presenting, we reviewed each presentation together and offered a constructive criticism.