<< Chapter < Page Chapter >> Page >

Overpopulation is a major problem in reducing greenhouse gas emissions, and in slowing down global warming. As populations grow, their demands on resources (e.g. energy) increase, and so does their production of greenhouse gases.

Ice core drilling - taking a look at earth's past climate

Global warming is a very controversial issue. While many people are convinced that the increase in average global temperatures is directly related to the increase in atmospheric concentrations of carbon dioxide, others argue that the climatic changes we are seeing are part of a natural pattern. One way in which scientists are able to understand what is happening at present, is to understand the earth's past atmosphere, and the factors that affected its temperature.

So how, you may be asking, do we know what the earth's past climate was like? One method that is used is ice core drilling . Antarctica is the coldest continent on earth, and because of this there is very little melting that takes place. Over thousands of years, ice has accumulated in layers and has become more and more compacted as new ice is added. This is partly why Antarctica is also on average one of the highest continents! On average, the ice sheet that covers Antarctica is 2500 m thick, and at its deepest location, is 4700 m thick.

As the snow is deposited on top of the ice sheet each year, it traps different chemicals and impurities which are dissolved in the ice. The ice and impurities hold information about the Earth's environment and climate at the time that the ice was deposited. Drilling an ice core from the surface down, is like taking a journey back in time. The deeper into the ice you venture, the older the layer of ice. By analysing the gases and oxygen isotopes that are present (along with many other techniques) in the ice at various points in the earth's history, scientists can start to piece together a picture of what the earth's climate must have been like.

One of the most well known ice cores was the one drilled at a Russian station called Vostok in central Antarctica. So far, data has been gathered for dates as far back as 160 000 years!

Case study : looking at past climatic trends

Make sure that you have read the 'Information box' on ice core drilling before you try this activity.

The values in the table below were extrapolated from data obtained by scientists studying the Vostok ice core. 'Local temperature change' means by how much the temperature at that time was different from what it is today. For example, if the local temperature change 160 000 years ago was -9 C, this means that atmospheric temperatures at that time were 9 C lower than what they are today. 'ppm' means 'parts per million' and is a unit of measurement for gas concentrations.

-textbfYears before present (x 1000) Local temperature change ( C) Carbon dioxide (ppm)
160 -9 190
150 -10 205
140 -10 240
130 -3 280
120 +1 278
110 -4 240
100 -8 225
90 -5 230
80 -6 220
70 -8 250
60 -9 190
50 -7 220
40 -8 180
30 -7 225
20 -9 200
10 -2 260
0 (1850) -0.5 280
Present 371


  1. On the same set of axes, draw graphs to show how temperature and carbon dioxide concentrations have changed over the last 160 000 years. Hint: 'Years before present' will go on the x-axis, and should be given negative values.
  2. Compare the graphs that you have drawn. What do you notice?
  3. Is there a relationship between temperature and the atmospheric concentration of carbon dioxide?
  4. Do these graphs prove that temperature changes are determined by the concentration of gases such as carbon dioxide in the atmosphere? Explain your answer.
  5. What other factors might you need to consider when analysing climatic trends?

Questions & Answers

any one who can help me with chemistry
george Reply
Yeah Sure. I will help
OK first can you pls teach me how to to calculate on chemistry chapter
What is a derivative?
Hydrocarbon derivatives are compounds that are made primarily of carbon and hydrogen atoms with specific groups of atoms attached. These specific groups of atoms are called functional groups. Hydrocarbon derivatives contain at least one element that is electronegative.
How to find the integral of a specific function?
how do u calculate the mass of an object if u have been given the gradient of a graph?
Hlelelwe Reply
what is endothermic reaction
Mphumuzi Reply
what is the difference between intramolecular and intermolecular forces
Xiluva Reply
please help me here how do the molecular masses of the compounds change?
Khutso Reply
how to calculate atom mass
Mbali Reply
how do water molecules form
Mukonazwothe Reply
water molecules consist of two atoms of hydrogen linked by covalent bonding to the same atom of oxygen ...hydrogen bonds are formed easily when two water molecules come close together , but are easily broken when the water molecule moves apart again
similarity between vander waals forces and hydrogen bond
Angel Reply
type of intermolecular forces between 2 hydrogen and 2 oxygen
when an atom X of an element in Group 1 reacts to become X+
Rhulani Reply
You have O.5 dm^3 of a KNO3 solution of concentration 0.2 M .You need to dilute this solution to get a solution of concentration 0.18M. calculate how many cubic cm of H2O you need to achieve this
Thimna Reply
im really struggling with this question please help me
I don't know how to help i nee you help
what is a radium
Zieniengie Reply
when 3.22 moles ofAl react with 4.96 moles HBr, how many moles of H2 are formed?
Devina Reply
how can we calculate the displacement?
Etaya Reply
can u tell me how to understand newtons law
Mutandanyi Reply
well they are many way to understand newtons but my way of understand it is to look every object around and think of what type of law has been applied in that object but fist state the law so you can get use to it
what is matter
Mutandanyi Reply
matter is any thing that has mass and occupy space

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now

Source:  OpenStax, Siyavula textbooks: grade 11 physical science. OpenStax CNX. Jul 29, 2011 Download for free at http://cnx.org/content/col11241/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Siyavula textbooks: grade 11 physical science' conversation and receive update notifications?