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19th February 2020
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Blue planet

Posted 25/07/2012 by sevans

From space, Earth is usually described as the Blue Planet. With around 70% of its surface covered by water, our home planet looks as though it has more than enough water to go around. Although most of this is saltwater in the oceans, and notwithstanding concerns over a lack of sufficient potable water in some parts of the world, most people would think that the Earth has a relatively large quantity of water.

But despite appearances, Earth is a dry planet, with just 1% of its mass accounted for by water. Astronomers have been convinced that this percentage should be much higher – a proposition that is all down to the very formation of our solar system. 

According to the standard theory of the solar system’s formation from a proto-planetary disk, the so-called common-accretion-disk model, the Earth should be a wet world. The planet should have been formed from icy material in the specific orbital range around the sun in which the temperatures were sufficiently cold to condense out the ices.

But a new analysis by US researchers at the Space Telescope Science Institute in Baltimore, Maryland, suggests that in fact the Earth was formed from rocky materials in a drier and hotter region, closer to the sun and inside what is described as the ‘snow line’, which is currently found around the orbit of the solar system’s asteroid belt. Planets outside this snow line orbit have much higher percentages of water. 

While this new analysis does have an impact on how planets circling other stars might be evaluated, it does little for us here on Earth. The maps recently created by Aqueduct, under the auspices of the US-based World Resources Institute, in its Water risk atlas, show the distribution of this essential resource around the globe. They are available here. 

 and are powered by previous Coca-Cola data collected over a number of years at locations where  the beverage company had manufacturing sites. 

Visitors to the website can create high resolution maps by combining hydrological data with geographically specific details, with the aim of helping companies use water more responsibly while helping them manage their risk exposure, says Aqueduct. Critics are more forthright, saying that companies will be able to cash in on this knowledge, making more money without taking the needs of local people into account, particularly those people in areas where water resources are scarce or spread thinly.

With two-thirds of the world’s population expected to face water shortages by 2025, we need all the help we can get to ensure that what water there is on our ‘dry’ planet is used efficiently and effectively by all its inhabitants.

Neil Eisberg - Editor

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