During today's class we will have the following learning goal:

​

​

 Understand that the Earth's climate can change due to atmospheric change.

 

​

The atmosphere is a layer of gas
above the Earth’s surface. It is very
different today from the atmosphere
when the Earth formed billions of
years ago.

 

Scientists think that the Earth was formed about 4600 million years ago. The Earth was very hot and it was molten for millions of years. Then, as the Earth cooled, a solid crust formed. There was a lot of volcanic activity, much more than there is now. The volcanoes produced gases, which formed the early atmosphere. Water vapour was produced by the volcanoes and, as the Earth cooled, this water vapour condensed into liquid water. The water fell as rain and formed the first lakes and oceans.

​

About 4000 million years ago, scientists think that the atmosphere contained mainly carbon dioxide, little or no oxygen, small amounts of the gases methane and ammonia, and some water vapour. This early atmosphere on Earth was like the atmosphere on Venus is today. The temperature on Venus is very high – on the surface, it is which is hot enough to melt lead.

​

​

​

​

​

​

​

​

 

​

 

 

 

Use the information above to answer these questions:

1) Where did the early atmosphere on Earth come from?

2) Give at least two differences between the early

atmosphere on Earth and the atmosphere today.

3) Explain why the Earth’s early atmosphere was not

suitable for us or any other animals.

​

​

​​

​

​

About 3500 million years ago, micro-organisms
developed on Earth. They lived in the oceans and
used the carbon dioxide in the atmosphere to make
food. They produced oxygen as a waste product of
this process. As plants developed over millions of
years, they began to grow on land. Plants use
carbon dioxide to produce food (glucose, a sugar)
by the process of photosynthesis:

Carbon dioxide + Water          Glucose + Oxygen

The levels of oxygen in the atmosphere continued
to rise. Scientists know this because there was
enough oxygen to combine with iron in the rocks
to form iron oxide.

200 million years ago there was very little carbon dioxide left in the atmosphere. Most of the carbon had been used to make the chemicals, which are part of all living things. When the organisms die and rot, the carbon in them is released back into the environment. It is recycled. Some organisms do not rot, when they die they are turned into fossil fuels such as oil or coal. The carbon is locked up in the fossil fuels until they are burned. Many organisms with shells evolved around 600 to 400 million years ago. The shells are made from calcium carbonate, CaCO3. When these shelled animals died and fell to the bottom of the oceans as sediment the many layers of shells pressing down on each other formed rocks, such as limestone. So carbon is also locked up in these rocks.

​

​

​

​

​

​

​

​

​​

​​

​​

​​

​​

4) What are fossil fuels?
5) How did the carbon dioxide in the atmosphere get used up?
6) What evidence is there that the levels of oxygen rose?
7) What two elements are present in carbon dioxide?
8) What three elements are present in calcium carbonate?
9) Limestone is a sedimentary rock. How is it formed?
10) When did carbon first start to be locked up?

​

​​

​

​

​

​

Last class we learned about the atmospheric changes that

happened thousands of years ago in our atmosphere, but

what about now? Human activity has a great impact

on the planet and its atmosphere, so today we will learn

about the changes Earth is facing today. 

​

THE CHANGE BEGAN 200 YEARS AGO

 

The amount of carbon dioxide in the atmosphere fell until about 200 years ago. Then the levels of carbon dioxide began to rise. Where is the carbon dioxide coming from? Humans caused this rise because they started to release the carbon that had been locked up in the Earth for millions of years. They burn fossil fuels, such as oil and coal, to keep themselves warm.

 

Carbon    +    Oxygen    ---->    Carbon  dioxide.

As humans developed industry and transport, they have burned more and more oil and coal. So there are greater emissions of carbon dioxide. Humans use a lot of fossil fuels to generate electricity in power stations.

​​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

1. Visit the ClimateKIDSNASA website, then define what is the green house effect and draw it on your notebook.

​

​

​

​

2. Go to the NAT GEO website and answer:

​

a) Write the name of the green house gases and their chemical formula.

b) What would happen to the Earth's temperature without the effect of these gases?

c) Mention 5 natural greenhouse gases and the way in which they are produced

d) Write 4 human activities that realease green house gases into the atmosphere

e) What can we do to reduce the production of these gases?

​

​3. Visit the BYJUS website and read about the difference between global warming and greenhouse effect, which one is the cause which is the effect? explain it with your own words.

​

​

​

​

​

​

​

​

​

​

​​

​

​

​

​

​

​

​

 

 

​

​

​​​

​

​

​

​

 

 

 

 

Every day, we use chemicals for farming, industry, and household products, but we don’t always think about where they end up. Many of these substances don’t just disappear—they enter the environment, build up in living organisms, and move through food chains, sometimes reaching dangerous levels. This process is called bioaccumulation and biomagnification. Over time, toxins that start in tiny organisms can become much more concentrated as they move up the food chain, eventually affecting larger animals—even humans. Although we’ve learned a lot, we still don’t fully understand how the chemicals we create impact entire ecosystems, including ourselves.

​

Let's start by watching this introductory video and completing the first activity:

​

​

​

​

​

1) Define: Bioaccumulation and Biomagnification.

​

2) Describe the example of bioaccumulation

​

3) Describe the example of biomagnification.

​

4) Read the following article about mercury

in tuna in Colombia and answer the questions:

​

a) What is the maximum concentration of mercury per Kg accepted in food in Colombia?

b) Why is tuna contaminated with mercury, if Tuna is an ocean fish and mercury is present in the rivers? Is this bioaccumulation or biomagnification?

c) Why is there mercury in the rivers of Colombia?

​​

5) Visit the Fiveable website, under the title "in the past" read and explain the DDT pesticide problem and summarize it with your own words.

​

6) in the CIMI website, read the 5 paragraphs about the POP problem and draw the food chin it affects and explain it with your own words.

​

​

​

​

​

​

​

​

​

​

​

​

​

​