C1bL16 Atmospheric Change

Key Words

Carbon sink - rocks that trap carbon dioxide.

Carbonic acid - a weak acid formed by the chemical reaction of carbon dioxide and water.

Climate change - average temperatures and weather patterns changing.

Global warming - average temperature across the whole world's surface increasing.

Photosynthesis - making sugars from carbon dioxide and water using energy from light.

Reforestation - planting lots of trees.

Test Yourself

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Grade E

In the past one hundred years, the average temperature across the world has risen by 1 oC.  While it doesn't sound a lot, there have been changes in weather patterns, which lead scientists to believe in climate change.  They say that carbon dioxide released form burning fossil fuels is leading to global warming.  This may have the following consequences:

  • Ice sheets will melt, leading to increases in sea levels.  Some low lying areas will be flooded.
  • The world's weather may change, becoming more extreme.
  • Some places will get hotter and drier, while others get colder.

 Not everyone accepts that carbon dioxide is causing global warming.  The Earth has periods where the climate is warmer, and periods where it is colder.

Grade C

Carbon dioxide is being captured from the atmosphere in different ways:

  • It reacts with rainwater to form carbonic acid (H2CO3);

  • Carbonic acid reacts with calcium minerals to form calcium carbonate, which is insoluble.  It drops to the bottom of the sea.

  • Calcium carbonate rocks (chalk and limestone) act as carbon sinks, because they trap the carbon dioxide.

  • Plants capture carbon dioxide in photosynthesis.  Coal is a sedimentary rock made from plants that captured carbon dioxide millions of years ago.  It, too, is a carbon sink.

  • Reforestation schemes help to capture carbon dioxide.

Greenhouse gases should not be got rid of completely (they can't be anyway).  Both carbon dioxide and water vapour are greenhouse gases.  Without them, the Earth would actually be very cold.

Grade A

 Scientists have to show evidence that global warming is taking place:

  • They have found that average temperatures have increased world-wide since 1910.  That does not mean that every place has got warmer; some places have got colder.

  • Carbon dioxide levels have increased from 280 parts per million to 320 parts per million in the thousand years between 1000 and 2000.  Most of that rise has been since 1900.

It is not a simple relationship, and there are many arguments over the whole issue.  Many politicians have seen votes in "green" agenda.