Whilst I have been reading millions upon millions of articles on water scarcity, one statement has always come up : around 2/3 of the earths population could face water stress of freshwater by the mid century.
But what about this other 1/3 I have wondered to myself?
Well luckily I have found out. Depending on the scenario and climate model used Alcamo et al , 2007 between 19.7% and 29% of total river basin area has decreasing stress and the remaining area has small changes ( less than 5% increase or decrease).
What is the cause of this decreasing water stress: climate change or human factors?
Well the primary factor for most of the area (approximately 50-80%) is the higher annual precipitation related to climate change. Whereas the main factor over a smaller area (about 20–45%) is decreasing withdrawals. The decrease or stabilisation in withdrawals are projected to be most apparent and extensive at industrialised regions. This is because it is believed that there will be a saturation of per capita water use, stabilising population and continued technological improvements..... so we were right last week about industrialised countries bringing us hope!! As for the major cause go this decrease over most of this area (59.7%- 88%, depending on the scenario) is the agriculture sector. The two most influential factors determine the decrease in agricultural withdrawals are increasing precipitation ( which reduces the demand for irrigation over the growing season) and improving efficiency of irrigation use.
So conclusion today is that climate change rather than humans is the most influential factor for projected REDUCTION in water stress.
So to be tackled in the next blog, the important and finale question: what is the factor most responsible for the INCREASE in water stress???
Will it be climate change as in the case of today, or humans… to be revealed next time at www.watersecurityhc.blogspot.co.uk
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