World water

Someone asked me what proportion of freshwater was stored in the cryosphere and I had no number for them, so I looked it up and found this great figure from the USGS along the way:

  • The largest sphere represents all of Earth’s water – a volume of 1,386,000,000 km– which is all the water in the oceans, ice caps, lakes, and rivers, as well as groundwater, atmospheric water, and in living organisms.
  • The middle sphere represents the world’s liquid fresh water (groundwater, lakes, swamp water, and rivers). The volume comes to about 10,633,450 km3, of which 99% is groundwater.
  • The smallest sphere represents fresh water in all the lakes and rivers on the planet, and most of the water people and life of earth need every day comes from these surface-water sources totalling 93,113 km3.

To answer the question: Estimates from scientific literature and websites of national agencies varied. Taking the UN to be an accepted standard source the UNEP says saltwater is 97.5% of all water on Earth, and the remaining 2.5% is freshwater. Of this freshwater, 70% is snow and ice, 30% is groundwater and 0.3% in rivers and lakes (obviously there is a degree of rounding of numbers in there). Note that the numbers given by the UN differ from those used in the graphic above.

About lindsey

Environmental scientist. I am glaciologist specialising in glacier-climate interactions to better understand the climate system. The point of this is to understand how glaciated envionments might change in the future - how the glaciers will respond and what the impact on associated water resources and hazard potential will be.
This entry was posted in resource efficiency. Bookmark the permalink.

Comments are closed.