Water scarcity 'biggest concern' of climate change
Up to one-fifth of the global population could suffer severe water shortages if the planet warms by two degrees above present levels, according to new research.
Initial results from an assessment on the impact global warming could have on societies and natural resources showed that climate-driven changes will result in a 40% increase in the number of people experiencing 'absolute' water scarcity.
Published in Proceedings of the National Academy of Sciences, climate change is expected to significantly affect the evaporation, precipitation and run-off of water which could mean that the extra 40% will have to survive on less than 500 cubic metres of water per person per year.
Absolute water scarcity, which is defined as less than 500 cubic meters available per year per person, requires extremely efficient water use techniques and management in order to be sufficient.
In comparison, the global average water consumption per person per year is roughly 1200 cubic meters, and significantly more in many industrialised countries.
Lead-author Jacob Schewe of the Potsdam Institute for Climate Impact Research said: "The steepest increase of global water scarcity might happen between two and three degrees global warming above pre-industrial levels, and this is something to be experienced within the next few decades unless emissions get cut soon.
"It is well-known that water scarcity increases, but our study is the first to quantify the relative share that climate change has in that, compared to - and adding to - the increase that is simply due to population growth," he added.
International Institute for Applied Systems Analysis director, and co-author, Pavel Kabat said: "The human costs of climate change are often triggered by the biophysical impacts, but are not identical to the impacts themselves. For example, water shortages in some regions might contribute to human conflicts and drive large-scale migration.
"We already have enough certainty today about climate change impacts to recognise it is high time to act. But as scientists we will work hard to further integrate and strengthen the existing expertise to better see the elephant in the room - and just how dangerous the mighty beast really is," added Kabat.
According to the study, climate change is not uniform across the world, explaining that the regional differences of its impacts on water availability are "huge".
It suggests that the Mediterranean, Middle East, the southern US, and southern China will "very probably" see a pronounced decrease of available water, while Southern India, western China and parts of Eastern Africa might see substantial increases.