Why is it happening?

Human activity is increasing the level of carbon dioxide at an unprecedented rate. Increases which would normally have occurred over centuries by normal natural processes have happened in less than a century because of human activity. This unnatural rapid increase places an added burden on any natural process which would remove carbon dioxide from the atmosphere to keep the atmosphere in equilibrium.

Where is it coming from?

 Carbon Dioxide Gas - Producing Processes

 Biomass Burning

Biomass burning sources include deforestation, grass fires in savannas to prepare range land for cattle, disposing of agricultural wastes, fuel wood for heating and cooking, production and use of charcoal, and natural wildfires.

Activity
  

 Industrial Emissions

Industrial emissions is a broad term covering any process which involves fossil fuel combustion. This includes industry, residential heating, transportation (cars, trucks, and aeroplanes), utilities, and commercial heating. Fossil fuels include coal, oil, and natural gas.

Activity

 

What processes remove carbon dioxide from the atmosphere?

Activity - Use the cut and paste facility on a computer program and an Internet connection to produce a poster about the 'Carbon Cycle' and any other ways that carbon dioxide can be removed from the atmosphere.

Are there other possible causes of climate change?

 Solar Output

  

The Earth's Orbit

Image of solar flares taken from the Yohkoh satellite

The sun has spots. Sunspots have 11 year cycles. Over the past centuries there have been periods with many sunspots and times when sunspots have been few. The data collect by satellite indicates that emits more energy during increased sunspot activity.

Could this be effecting global temperatures?

Try analysing this sunspot data. (Excel spreadsheet)

  • Look for years of high sunspot activity.
  • What was the average global temperatures for those years.
 

 Earth's orbit is not constant. Over a period of 90,000 to 100,000 years, Earth's orbit stretches into a longer ellipse and then returns to a more circular shape.

The tilt of Earth's axis is also not constant. It varies between 22.1° and 24.5° during a cycle, which takes 41,000 years. The smaller the tilt, the smaller the difference between winter and summer.

All three of these effects cause little change in the annual amount of solar energy reaching Earth. Their effect is to change the contrast between the seasons. Milutin Milankovitch, a Yugoslavian astronomer, plotted out these three changes to Earth's orbital geometry. He found that these changes were closely associated with changes in climate.

Could this be causing the warm up?

Do you think that it is a good idea to cut down on the amount of carbon dioxide gas we produce?

The next section will look at what you can do.

My Carbon Dioxide

Back to the evidence

Images courtesy of Environmental Defence http://www.edf.org/pubs/Brochures/GlobalWarming/ and Exploring the environment http://www.cotf.edu/ete/main.html