Water. Similar to oxygen, the other key resource that is essential for life to exist on the planet. While everyone assumes that the planet has enough water this is both misleading and are under threat. One key fact is that 97% of all water is salt water, only 3% of all available water is fresh water with 67% frozen in glaciers and the polar ice caps. It is fresh water that is the key component for survival for terrestrial wildlife, birds and humans.
While fresh water is a renewable resource there are however many threats that could have drastic effects on planet life. Threats such are climate change, water pollution and water scarcity are having a negative effect on this renewable resource. Excluding glaciers and the polar ice caps, today the only other available resource is groundwater which have over a period of years been decreasing with depletion now evident prominently in Asia along with North and South America.
While there are artificial sources for useable water such as wastewater filtration / reuse and desalination water (converting saline water into drinking water, both of these alternatives require extensive technological expertise which is not available to poorer countries and also require high energy consumption to convert saline water to fresh water.
Other links:
https://www.youtube.com/watch?v=odngssDFMrU
https://scholar.google.com/scholar?q=water+resource+management&hl=en&as_sdt=0&as_vis=1&oi=scholart
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014WR016869
https://waterfdn.org/sustainable-water-management-swm-profile/
