Life on Exoplanets
Astrophysicist Didier Queloz on whether we can find life on Mars, Proxima Centauri, and the importance of oxyg...
Weirdly enough, we will never run out of fresh water. I think that surprises a lot of people because you think of fresh water as being this very precious commodity, but from work that’s been done over the last couple of years, we know that the amount of freshwater globally has actually increased compared to the amount that has been lost. So, in terms of quantity, we will not run out of fresh water.
We do have these concepts called ‘planetary boundaries’, which suggest a global use of freshwater, but that doesn’t really make sense because the problem with fresh water is that it’s so unevenly distributed around the world that some places are rich in the resource. They’ll never run out, whereas in other places, the resource is very limited, and that is where the problems can arise.
Instead of having a planetary boundary, what’s probably a better way to think about it is to have a regional boundary or to think about fresh water in terms of environmental water flows. So we should be looking at fresh waters in the unit of, say, the catchment: that is, the lake and all the rivers that flow into it. If we take out more water than flows through a river in a month, then that is going to pose problems for freshwater security. If you take out a lot of water that flows for many months from a river going into the lake, then that is clearly very problematic, and in that situation, we will see an example of when freshwater becomes limiting, and that’s when we have to take care.
There are some very good examples of that around the world, such as the Aral Sea in Uzbekistan and Kazakhstan, but also Lake Urmia in Iran, which is following a similar type of fate where 40 000 illegal wells are extracting water faster than it can flow into the lake.
Astrophysicist Didier Queloz on whether we can find life on Mars, Proxima Centauri, and the importance of oxyg...
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