Earth Day is the perfect time to think about water. Drought is one of the major outcomes associated with climate change. Deep in the heart of Texas, prolonged drought has helped spawn record wildfires, which have already burned over 1 million acres with no end in sight. Talking about the connection between climate change and drought is somewhat taboo in Texas for fear that the oil industry might get unfavorable attention. Perhaps that is why Governor Rick Perry has opted to pray for rain and hope the drought is just bad weather luck rather than a harbinger of hell on earth. (I pray that God smite stupid and dishonest politicians, but so far that has not happened.)
Much has changed since the first Earth Day celebration in 1970. I remember planting trees, picking up trash, and listening to a lecture on how a pesticide was bringing raptor populations to the brink of extinction. Those were simpler times before science zeroed in on the potential for climate change from our prodigious use of fossil fuels. By the 80th anniversary of Earth Day, many across Asia, Africa, and Central America are likely to suffering from severe water shortages due to climate change.
A recent study published in the Proceedings of the National Academy of Sciences looked at the connection between climate change, population growth, and water shortages in urban areas by 2050 ("Urban growth, climate change, and freshwater availability").
Modeled results show that currently 150 million people live in cities with perennial water shortage, defined as having less than 100 L per person per day of sustainable surface and groundwater flow within their urban extent. By 2050, demographic growth will increase this figure to almost 1 billion people. Climate change will cause water shortage for an additional 100 million urbanites. Freshwater ecosystems in river basins with large populations of urbanites with insufficient water will likely experience flows insufficient to maintain ecological process. Freshwater fish populations will likely be impacted, an issue of special importance in regions such as India's Western Ghats, where there is both rapid urbanization and high levels of fish endemism. Cities in certain regions will struggle to find enough water for the needs of their residents and will need significant investment if they are to secure adequate water supplies and safeguard functioning freshwater ecosystems for future generations.
Drought secondary to climate change is forecast to impact the human population in two ways. First, drought in rural areas will likely drastically reduce food production and limit our ability to feed 9 billion mouths by 2050. Second, with more humans concentrated in urban areas, drought will impact our ability to provide minimum water requirements by 2050. This is the issue that Robert McDonald and colleagues examined in the PNAS report.
What McDonald and his research team did was to combine data from population projections, hydrological data, and mid-range climate change models to estimate water shortages in urban areas expected by 2050. Population data were drawn from the Global Rural–Urban Mapping Project and forecasts for target cities. The "ecological factors" scenario adjusts population projections for specific biomes, which allows researchers to incorporate fertility and mortality trends associated with environmental constraints. The population data was combined with hydrological data from the Water Balance Model and mid-range climate change models developed for the 2007 Intergovernmental Panel on Climate Change.
The results of these models suggest that up to 3 billion people living in urban environments will face seasonal water shortages and up to 1 billion people will face perennial water shortages. In order to limit the impact, these urban populations will be forced to draw water from up to 100 km away, which will drastically increase cost. Here is how they crunch the numbers.
Urban population can be usefully divided into three categories reflecting their perennial water shortage status. A total of 162 million people will live in cities that will have perennial water shortage in 2050. The majority of people in this category will be in Asia (94 million), although Africa will have a greater percentage (7.7%) of total urban dwellers under perennial water shortage. A second category is people in cities that will not have perennial water shortage by 2050 at the 100-km buffer distance, but the buffer distance needed to avoid perennial water shortage will increase from 2000 to 2050. This potentially implies infrastructure investment to enable short-scale (<100 km) water transport to satisfy the needs of a projected 2050 population of 720 million. Again, the majority of people in this category will be in Asia (338 million), but Africa will have a greater percentage (36.3%) of total urban dwellers in this category. Finally, a third category is people in cities that do not seem likely to have problems with perennial water shortage, whose population will grow from 1.0 billion to 2.9 billion from 2000 to 2050. Many city dwellers who fall into this residual category will, however, face seasonal water shortage.
Here is a graphic representation of where those shortages are likely to be particularly severe.
The water shortages for the human population will also create severe pressures on aquatic life. The areas that are likely to have draw large quantities of water from rivers and lakes to meet human consumption needs are also some of the most productive aquatic environments. In fact, many of these aquatic environments currently supply fish to feed the region's human population. Meeting the demand for water will mean pushing many fish species to the brink of extinction.
The researchers suggest that population growth and climate change will create three major challenges for the water-stressed populations of Asia, Africa, and Central America. First, there will be engineering challenges to transport freshwater from regional sources, desalination for coastal areas, and wastewater reclamation and treatment. Second, water limitations will create strains on agricultural productivity. Finally, meeting the water needs for the human population is likely to be an extremely expensive proposition. Like every environmental issue, the people with the fewest resources will suffer the most from rising water costs.
One issue that the study does not discuss is the prodigious use and degradation of water resources for energy extraction and consumption. For example, hydraulic fracturing of a single shale gas well produces millions of gallons of toxic wastewater over the life of the well. Producing oil from tar sands and shale consumes and pollutes water on an absurd scale. The water impact is bad enough for tar sands and shale oil production in water rich environments like Alberta, but obscene and unconscionable in water scarce areas like Utah and Colorado. Mountaintop removal mining is deliberately destroying water resources throughout Appalachia. And then there is the indirect effect of greenhouse gas emissions on climate change and drought. Let me put this as nicely as I possibly can. So little water, so goddamn much stupidity.
Supplying the world's urban dwellers with adequate water in 2050 will pose a challenge. More than 1 billion people will live in cities without sufficient available water within their urban extent, and these cities will need to invest in other ways to get water. It is a solvable problem but one that will take money, time, political will, and effective governance. For countries with moderate to high per-capita income, domestic investments seem likely to be adequate to find solutions to water shortage if sufficient political will can be found. However, for countries with low per-capita income, domestic investment is likely to be inadequate, and new financing institutions and commitments by the international community will be needed. These kinds of commitments are crucial if the world is to ensure that all urban residents can enjoy their fundamental human right to adequate drinking water.
Color me pessimistic about the prospects for political will, effective governance, and above all else commitment to the greater good to ensure the fundamental human right to water.
In my corner of world, my goal is reduce my water footprint as much as possible through efficiency. Our outdoor water needs are now supplied by rain barrels. Last year, we were able to maintain water for the garden from the rain barrels. It is a bit more time and labor intensive to distribute the water where needed, but worth the effort. The short distance I have carry watering cans to reach every corner of my garden to dowse the thirsty plants is nothing compared to the effort required by people in Africa, traditionally women. I keep them in mind with every step I take during the growing season.
Well, maybe we should think about drinking more beer in the future. As this graphic shows, the beer of the future will likely be warm and crappy. Tough to grow grain and brew beer without water.
Celebrate Earth Day while we still can.