It is a well-known fact that water is the key to life on Earth. But it is less well known that only about 1% of all water on the planet is fresh water available to humans, plants or land-based animals.
The rest is in the oceans, or locked up in polar ice sheets and rocks. In a climate changing world, the global distribution of that 1% takes on a whole new significance.
A new study published in Science has shown that the southern hemisphere has been drying out more than the northern hemisphere over the past two decades (2001–2020). The authors suggest the principle cause is the weather phenomenon known as El Niño, which occurs every few years when ocean water in the eastern Pacific is warmer than usual.
The findings are based on data from satellites and measurements of river and stream flows, which enabled the authors to model and calculate changes in water availability. Water availability is the net difference between the amount of water supplied to the landscape, in the form of rainfall on land, and the water removed to the atmosphere by general evaporation or by plants through their leaves.
Even though the southern hemisphere has only a quarter of the global land area (excluding Antarctica), it appears to have a substantially greater effect on global water availability than the northern hemisphere.
2023-11-03 11:41:03
Original from phys.org
