Rights: The University of Waikato Published 15 April 2009 Download

On a global scale, the burning of fossil fuels is affecting the global climate. Scientists are detecting an increase in temperature in the atmosphere, and as the temperature increases, its ability to hold water also increases.

An increase of fossil fuel emissions, particularly carbon dioxide or CO2, has been linked with an increase of carbon dioxide that is being absorbed by the oceans, making the oceans more acidic. Scientists are concerned that increased acidity will endanger shellfish, corals and crustaceans.

Points of interest
How much carbon dioxide from fossil fuels is believed to have ended up in the oceans? What is the main problem for shellfish, corals and crustaceans if the ocean’s acidity rises?


Some human activity affects the climate on earth, for example, it is believed that the burning of fossil fuels contributes to the greenhouse effect, which is thought to be raising the earth's temperature.

Many scientists believe that changing the temperature of the atmosphere and the evaporation rate is very much determined by energy supply and temperature, and the amount of water vapour that the air can hold is pretty much a function of air temperature. So as the temperature of the atmosphere rises, then the atmosphere will be able to hold more water. The converse of that is perhaps we will get more clouds, and clouds can then reflect more solar radiation.

The greenhouse effect affects the temperature in the atmosphere and in the ocean. It also increases the level of carbon dioxide in the sea, making it more acidic, which can be a problem to some animals that live in the sea.

It is quite clear from recent research that humans are having a measurable impact on the ocean system – we can measure the increase in temperature caused by warming. But perhaps one of the more subtle ones has been we have now been able to measure the excess carbon dioxide produced from fossil fuel burning that is being absorbed by the ocean. Between a third and a half of all the fossil fuel CO2 has actually ended up in the ocean. The ocean is a huge reservoir of CO2 – it’s 50 to 100 times larger than the atmosphere – so if you wait long enough, all the CO2 from fossil fuel burning will eventually end up in the ocean. But unfortunately it takes thousands of years for the ocean to mix itself up and so the CO2 builds up in the surface of the ocean and in the atmosphere because the ocean doesn't mix up fast enough. So one of the things that will happen and is happening is that CO2 builds up and the ocean gets slightly more acidic.

Mathew Allan, University of Waikato
NASA/courtesy of nasaimages.org
NASA/Goddard Space Flight Center Scientific Visualization Studio