The World in 2050: Four Forces Shaping Civilization's Northern Future (41 page)

223
J. I. Uitto, A. T. Wolf, “Water Wars? Geographical Perspectives: Introduction,”
The Geographical Journal
168, no. 4 (2002): 289-292; T. Jarvis et al., “International Borders, Ground Water Flow, and Hydroschizophrenia,”
Ground Water
43, no. 5 (2005): 764-770.

224
W. Barnaby, “Do Nations Go to War over Water?”
Nature
458 (2009): 282-283.

225
Water “withdrawal” refers to the gross amount of water extracted from any source in the natural environment for human purposes. Water “consumption” refers to that part of water withdrawn that is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment. Global “blue water” withdrawals from rivers, reservoirs, lakes, and aquifers are estimated at 3,830 cubic kilometers, of which 2,664 cubic kilometers are used for agriculture. Pp. 67-69,
Water for Food, Water for Life: A Comprehensive Assessment of Water Management in Agriculture
(London: Earthscan, and Colombo: International Water Management Institute, 2007), 665 pp.

226
The term
virtual water
was coined by J. A. Allan in the early 1990s, e.g., “Policy Responses to the Closure of Water Resources,” in
Water Policy: Allocation and Management in Practice
, P. Howsam, R. Carter, eds. (London: Chapman and Hall, 1996).

227
The global transfer of virtual water embedded within commodities is estimated at 1,625 billion cubic meters per year, about 40% of total human water consumption. A. K. Chapagain, A. Y. Hoekstra, “The Global Component of Freshwater Demand and Supply: An Assessment of Virtual Water Flows between Nations as a Result of Trade in Agricultural and Industrial Products,”
Water International
33, no. 1 (2008): 19-32. See also pp. 35 and 98, UN World Water Assessment Programme,
The United Nations World Water Development Report 3: Water in a Changing World
(Paris: UNESCO, and London: Earthscan, 2009), 318 pp.

228
R. G. Glennon,
Water Follies: Groundwater Pumping and the Fate of America’s Fresh Waters
(Washington, D.C.: Island Press, 2002), 314 pp. Windmills and other early technology could lift water from a maximum depth of only seventy to eighty feet, but the centrifugal pump, powered by diesel, natural gas, or electricity, could lift water from depths as great as three thousand feet.

229
Figure 7.6, UN World Water Assessment Programme
, The United Nations World Water Development Report 3: Water in a Changing World
(Paris: UNESCO, and London: Earthscan, 2009), 318 pp.

230
U.S. Geological Survey, “Estimated Use of Water in the United States in 2000,” USGS Circular 1268, February 2005.

231
Other materials can also make good aquifers, for example gravel or highly fractured bedrock.

232
See M. Rodell, I. Velicogna and J. S. Famiglietti, “Satellite-based Estimates of Groundwater Depletion in India,”
Nature
460 (2009): 999-1002, DOI:10.1038/nature08238; and V. M. Tiwari, J. Wahr, and S. Swenson, “Dwindling Groundwater Resources in Northern India, from Satellite Gravity Observations,”
Geophysical Research Letters
36 (2009), L18401, DOI:10.1029/2009GL039401.

233
Also known as the High Plains Aquifer, the Ogallala underlies parts of Kansas, Nebraska, Texas, Oklahoma, Colorado, New Mexico, Wyoming, and South Dakota. Other material in this section drawn from V. L. McGuire, “Changes in Water Levels and Storage in the High Plains Aquifer, Predevelopment to 2005,” U.S. Geological Society Fact Sheet 2007-3029, May 2007.

234
Human drawdown averages around one foot per year, but natural replenishment is less than an inch per year. Telephone interview with Kevin Mulligan, April 21, 2009.

235
“Useful lifetime” is projected time left until the saturated aquifer thickness falls to just thirty feet. When the aquifer is thinner than thirty feet, conventional wells start sucking air, owing to a thirty-foot cone of depression that forms in the water table around the borehole. The described GIS data and useful lifetime maps for the Ogallala are found at
http://www.gis.ttu.edu/OgallalaAquiferMaps/
.

236
LEPA drip irrigation systems create a smaller cone of depression, allowing water to be sucked from the last thirty feet of remaining aquifer saturated thickness. Therefore a switch to LEPA can prolong the usable aquifer lifetime another ten to twenty years, but cannot stop the outcome.

237
Notably the Netherlands, France, Germany, and Austria. P. H. Gleick, “Water and Energy,”
Annual Review of Energy and the Environment
19 (1994): 267-299. This is not to say all of the water used is irrevocably lost; most power plants return most of the heated water back to the originating river or lake. See note 225 for withdrawal vs. consumption.

238
This is the legal maximum in the European Union, but recommended “guideline” temperatures are lower, around 12-15 degrees Celsius in the EU and Canada. Ibid
.

239
See also his book on wind power. M. Pasqualetti, P. Gipe, R. Righter,
Wind Power in View: Energy Landscapes in a Crowded World
(San Diego: Academic Press, 2002), 248 pp.

240
The reason for this is the very large water losses that evaporate from the open reservoirs behind hydroelectric dams.

241
For example, see P. W. Gerbens-Leenes, A. Y. Hoekstra, T. H. van der Meer, “The Water Footprint of Energy from Biomass: A Quantitative Assessment and Consequences of an Increasing Share of Bio-energy in Energy Supply,”
Ecological Economics
68 (2009): 1052-1060.

242
Telephone interview with M. Pasqualetti, April 14, 2009.

243
T. R. Curlee, M. J. Sale, “Water and Energy Security,”
Proceedings,
Universities Council on Water Resources, 2003.

244
For climate model simulations of Hadley Cell expansion, see J. Lu, G. A. Vecchi, T. Reichler, “Expansion of the Hadley Cell under Global Warming,”
Geophysical Research Letters
34 (2007): L06085; for direct observations from satellites, see Q. Fu, C. M. Johanson, J. M. Wallace, T. Reichler, “Enhanced Mid-latitude Tropospheric Warming in Satellite Measurements,”
Science
312, no. 5777 (2006): 1179.

245
P. C. D. Milly, K. A. Dunne, A. V. Vecchia, “Global Pattern of Trends in Streamflow and Water Availability in a Changing Climate,”
Nature
438 (2005): 347-350.

246
G. M. MacDonald et al., “Southern California and the Perfect Drought: Simultaneous Prolonged Drought in Southern California and the Sacramento and Colorado River Systems,”
Quaternary International
188 (2008): 11-23.

247
The medieval warming was triggered by increased solar output combined with low levels of volcanic sulfur dioxide in the stratosphere, whereas today the driver is greenhouse gas forcing. The comparison between the medieval warm period and today is imperfect because the former saw temperatures rise most in summer, whereas greenhouse gas forcing causes maximum warming in winter and spring. Still, the medieval warm period is the best “real world” climate analog scientists have for examining possible biophysical responses to projected greenhouse warming. For more, see G. M. MacDonald et al., “Climate Warming and Twenty-first Century Drought in Southwestern North America,”
EOS, Transactions, AGU
89 no. 2 (2008). For more on the Pacific Decadal Oscillation, see G. M. MacDonald and R. A. Case, “Variations in the Pacific Decadal Oscillation over the Past Millennium,”
Geophysical Research Letters
32, article no. L08703 (2005), DOI:10.1029/2005GL022478.

248
R. Seager et al., “Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America,”
Science
316 (2007): 1181-1184.

249
P. C. D. Milly, J. Betancourt, M. Falkenmark, R. M. Hirsch, Z. W. Kundzewicz, D. P. Lettenmaier, R. J. Stouffer, “Stationarity Is Dead: Whither Water Management?”
Science
319 (2008): 573-574.

250
The confusion arises from the fact that the “hundred-year flood,” “five-hundred-year flood,” etc., are simply statistical probabilities expressed as a flood height. This leads the common misperception that a hundred-year flood happens only once every hundred years, a five-hundred-year flood happens only once every five hundred years, and so on. In fact, the probability is 1/100 and 1/500 in any given year. The likelihood of enjoying a hundred consecutive years without suffering at least one hundred-year flood is just (99/100)
¹⁰⁰
= 37%.

251
For example, it now appears likely that climate change will increase risk uncertainty with crop yields. B. A. McCarl, X. Villavicencio, X. Wu, “Climate Change and Future Analysis: Is Stationarity Dying?”
American Journal of Agricultural Economics
90, no. 5 (2008): 1241-1247.

252
P. C. D. Milly, J. Betancourt, M. Falkenmark, R. M. Hirsch, Z. W. Kundzewicz, D. P. Lettenmaier, R. J. Stouffer, “Stationarity Is Dead: Whither Water Management?”
Science
319 (2008): 573-574.

253
D. P. Lettenmaier, “Have We Dropped the Ball on Water Resources Research?”
Journal of Water Resources Planning and Management
134, no. 6 (2008): 491-492.

254
The company, State Farm Florida, sent cancellation notices to nearly a fifth of its 714,000 customers after failing to win a 47.1% rate hike from state regulators. In the same year Florida’s Office of Insurance Regulation projected that 102 of the 200 largest Florida insurance carriers were running net underwriting losses. “State Farm Cancels Thousands in Florida,” February 23, 2010,
http://www.msnbc.msn.com/id/35220269/ns/business-personal_finance/
.

255
P. W. Mote et al.,
Bulletin of the American Meteorological Society
86, no. 1 (2005): 39-49.

256
T. P. Barnett et al., “Human-Induced Changes in the Hydrology of the Western United States,”
Science
319 (2008): 1080-1083.

257
J. Watts, “China Plans 59 Reservoirs to Collect Meltwater from Its Shrinking Glaciers,”
The Guardian,
March 2, 2009; “Secretary Salazar, Joined by Gov. Schwarzenegger, to Announce Economic Recovery Investments in Nation’s Water Infrastructure,” U.S. Bureau of Reclamation Press Release, April 14, 2009; “California to Get $260 Million in U.S. Funds for Water,” Reuters, April 15, 2009.

258
Melting glacier ice and the thermal expansion of ocean water as it warms are the two most important contributors to sea-level rise. Thermal expansion of ocean water is a relatively sluggish process that is still responding to warming of past decades and will continue in response to more warming in the pipeline. To date, roughly 80% of the heat from climate warming has been absorbed by oceans. A very recent post-IPCC study estimates that over the period 1900-2008 thermal expansion caused 0.4 ± 0.2 mm/yr of sea-level rise, small glaciers and ice caps 0.96 ± 0.44 mm/yr, the Greenland Ice Sheet 0.3 ± 0.33 mm/ yr, the Antarctic Ice Sheet 0.14 ± 0.26 mm/yr, and terrestrial runoff 0.17 ± 0.1 mm/yr. C. Shum, C. Kuo, “Observation and Geophysical Causes of Present-day Sea Level Rise,” in
Climate Change and Food Security in South Asia
, ed., R. Lal, M. Sivakumar, S. M. A. Faiz, A. H. M. Mustafizur Rahman, K. R. Islam (Springer Verlaag, Holland: in press). Construction of twentieth-century impoundments may have trapped back ~30 mm sea level equivalent in total, an average of -0.55 mm/yr. B. F. Chao, Y. H. Wu, and Y. S. Li, “Impact of artificial reservoir water impoundment on global sea level,”
Science
320 (2008): 212-214. However, the trapping effect of human impoundments has since slowed or even reversed. D. P. Lettenmaier, P. C. D. Milly, “Land Waters and Sea Level,”
Nature Geoscience
2 (2009): 452-454, DOI:10.1038/ngeo567.

259
S. Rahmstorf et al., Response to Comments on “A Semi-Empirical Approach to Projecting Future Sea-Level Rise,”
Science
317, 1866d (2007). (See erratum for updated sea-level rise rates.)

260
M. Heberger, H. Cooley, P. Herrera, P. H. Gleick, E. Moore, “The Impacts of Sea-Level Rise on the California Coast,” Final Paper, California Climate Change Center, CEC-500-2009-024-F (2009), 115 pp., available at
http://pacinst.org/reports/sea_level_rise/report.pdf
.

261
The 2007
IPCC AR4
“consensus estimate” of 0.18 to 0.6 meters by 2100 may be too low. Other estimates suggest a possible range of 0.8-2.0 meters (W. T. Pfeffer et al., “Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise,”
Science
321, no. 5894 2008: 1340-1343) and 0.5-1.4 meters (S. Rahmstorf, “A Semi-Empirical Approach to Projecting Future Sea-Level Rise,”
Science
315, no. 5810 [2007]: 368-370, DOI:10.1126/science.1135456.)