Ask an expert: Water on earth increasing?

By AG STAFF 7 November 2013
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A reader wants to know whether fossil fuel burning has increased the planet’s water stores.

QUESTION: With the increase in CO2 in our atmosphere from burning fossil fuels, is there more water on the planet than there was hundreds of years ago? My understanding is that burning hydrocarbons produces water vapour in addition to carbon dioxide.
Peter Campbell, Corlette, NSW

Professor Barry Brook, environmental scientist at the University of Adelaide, says:

Yes, the burning of fossil fuels has generated more water, but the amount is negligible compared with the amount of water on the planet.

Up to the year 2000 humans had burnt about 110 billion tonnes of oil, 50 billion tonnes of gas and 250 billion tonnes of coal. Water generated from combustion from these fuels is about 340 billion tonnes, or

This might sound like a lot, but to put that in perspective, the volume of Sydney Harbour is about So we’re only talking about filling Sydney Harbour six times over – that’s about 0.000025 per cent of the water in all the world’s oceans, meaning this really is a ‘drop in the ocean’!

There is more water vapour in our atmosphere today than in the past, but this is due to the increased evaporation of water from warmer oceans.

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