Urban growth, climate change, and freshwater availability Robert I. McDonald, Pamela Green, Deborah Balk, Balazs M. Fekete, Carmen Revenga, Megan Todd, and Mark Montgomery

 There are currently about 1.2 billion people living in cities in developing countries  The number of people living in cities is expected to grow by 3 billion by the year 2050  74% of that growth is expected to occur in developing nations Just how many people live in cities, anyway?

 The article defines a water shortage as an area having less than 100 liters of freshwater per person per day.  Perennial vs. seasonal  Although freshwater provision is defined in three terms (water availability, water quality, and ease of delivery), this article focuses only on water availability, which is the physical amount of freshwater in an area. What exactly is a water shortage?

 As of the year 2000, there are 150 million people living in urban areas with perennial water shortage.  886 million people live in cities that experience seasonal water shortage.  In the year 2050, that number is expected to jump to 993 million with perennial shortage and 3.1 billion with seasonal shortages.  How will developing countries develop if they don’t have enough water? “Water, water every where, Nor any drop to drink”

 In order to calculate which urban areas will be in danger of water shortage, the scientists used data on population distribution from the Global Rural-Urban Mapping Project, aka GRUMP, to block out different urban areas.  They then looked at whether or not that area currently has enough water and if it will have enough water in the future.  If the area didn’t meet the minimum standard, it was then re-examined taking into account the water availability within a 100 km radius (called a buffer zone) How exactly do we know this?

 After zoning the areas using GRUMP, the researchers calculated the water balance using the Simulated Topological Network model, inputting current temperature and precipitation data for the areas to achieve the 2050 projections.  They then simulated the 2050 climate using four different greenhouse gas emission scenarios from the Millennium Ecosystem Assessment. The Procedure

 Remember the question: How will developing countries develop if they don’t have enough water?  The freshwater ecosystems of these areas are also affected  Ex: The fish species in the Western Ghats of India, 29% of which live nowhere else in the world  These are the projections for the next 40 years But why should I care if India and China aren’t going to have enough water?

 Because this research topic deals with projected numbers, it’s impossible to tell exactly what will happen in the future and what the consequences of a potential water shortage will be.  Options for the future? Some final thoughts