3. El capitalismo y la configuración de espacios geográficos
3.1 La configuración de las relaciones desiguales del libre mercado en la era de la
The latest climate projections from 14 of the world’s leading climate modelling centres were used by Forster et al. (2012) to examine the potential risks to food production for wheat, maize and rice across Asia from climate change-driven drought in the 2020s. An analysis of adaptive capacity was also conducted, based on projections of seven key socio-economic drivers, to determine which crop- producing regions are most vulnerable to climate change-driven drought. Forster et al. (2012) showed that:
1. There is an increased risk of more severe droughts in the 2020s. Compared to the period 1990–2005, the 2020s will bring marked increases in drought severity across much of Asia, with larger deficits in soil moisture over longer periods of time. Immediate actions are needed so as to adapt. Water resource management can mitigate impacts of all but the most severe and prolonged droughts. This would include sustainable use and safeguarding of groundwater supplies as well as improved harvesting of rainfall.
2. The increased risk of drought severity presents a global-scale challenge to food security. The 2020s will bring significant increases in drought severity for northern parts of China and India, Afghanistan, Mongolia and Pakistan. This presents a global risk to food security, as China and India are the world’s largest food producers. China is currently one of the best placed to adapt effectively, but other countries may suffer without effective adaptation strategies. India is forecast to get slightly wetter, but is predicted to have low adaptive capacity, putting its large harvests of wheat and maize under continued, but not increasing, threat.
3. Projected adaptive capacity is driven by local and regional characteristics. The ability to adapt to droughts in the very near future depends on local contexts. Regions with the greatest reductions in adaptive capacity from 1990–2005 to the 2020s are those with authoritarian regimes and/or arid ecosystems. Adaptive capacity is projected to be relatively strong in China and relatively weak in India, Afghanistan and Western Russia. Additional fertiliser use in tropical and arid countries may buffer wheat yields from drought, while high rural populations in temperate climates may help to buffer maize yields against drought through labour-intensive adaption strategies. Forster et al. (2012) found no adaptive capacity relationship for rice. They suggest that this is possibly because much of the world’s rice is irrigated, uses improved varieties and benefits from fertiliser inputs, and is therefore not as affected by changes in soil moisture as are wheat or maize.
BOX 1.3 CONTEMPORARY CHALLENGES
REFLECTIVE QUESTION
Why do some people state that there is a global water crisis?
F SUMMARY
Water is a unique substance having important physical and chemical properties, brought about by its covalent bonds and its polar hydrogen bonds, which enable it to act as an excellent solvent, to weather and erode the landscape and to regulate climate. Water is necessary for photo - synthesis and for the survival of all forms of life. Water has been pivotal to the development of civilisations through its use in developing societal power relations formed by the onset of agriculture and developed over the past 13,000 years. Control of water resources enabled agriculture, which allowed non-farmers to specialise in other activ - ities, some of which could be traded for food. In modern society, as in ancient civilisations, water has economic, religious and symbolic significance. Today the main use of water by humans world - wide, by volume, is in agriculture and the pro -
cessing of agricultural products. Hence a focus on agricultural water efficiency is crucial for the future as the world’s population grows and places enormous pressure on global water resources. There are already 45 countries that have less than 1000 m3of renewable water resource avail -
able per person per year. This water is needed for agri culture, industry and domestic use. It is anticipated that many more countries will reach this water ‘stress’ threshold in the coming years as the water crisis hits hard. These include large, populous countries in Asia such as India and China. Around 44 countries rely on other coun - tries to provide more than half of their water supply. Thus water security for individual nations is of great importance and typically requires a balance of technological, socio-economic and pol - it ical solutions. Interdisciplinary water research is therefore necessary to enable us to reduce the impacts of the global water crisis.
FURTHER READING
Hassan, F.A. 2012. Water management and early
civilizations: from cooperation to conflict. Report
prepared for the UNESCO–Green Cross Inter - national project From Potential Conflict to Co- operation Potential (PCCP): Water for Peace [online]. Available from: http://tinyurl.com/ 6tebpg5.
An interesting essay on the development of civilisations and water cooperation and water conflict.
Molden, D. (ed.). 2007. Water for food, water for life. Earthscan; London and International Water Management Institute; Colombo.
An excellent resource full of useful facts, theory and necessary adaptation strategies for the future. Shiklomanov, I. 1998. World water resources. UNESCO;
Milton Keynes.
Important text demonstrating water resource inequalities.
Waley, P. and Åberg, E.U. 2011. Finding space for flowing water in Japan’s densely populated landscapes.
Environment and Planning A 43: 2321–2336.
This is a useful article that illustrates some inter est- ing tensions between symbolic and cultural identity and pragmatic protection of people from water threats. It provides more information relevant to Box 1.1.
Classic papers On the properties of water:
Bernal, J.D. and Fowler, R.H. 1933. A theory of water and ionic solution, with particular reference to hydrogen and hydroxyl ions. Journal of Chemical Physics 1: 515–549.
Pople, J.A. 1951. Molecular association in liquids. II. A theory of the structure of water. Proceedings of the
Royal Society of London A 205: 163–178.
On global water resources:
Vörösmarty, C.J., Green, P., Salisbury, J. and Lammers, R.B. 2000. Global water resources: vulnerability from climate change and population growth, Science 289: 284–288.
n Look for reports and data on the Internet that report past or predict future water use for
different countries over time. Try to partition the relative roles of climate change, population growth and development on changing water use for some selected countries.
n Produce a list of agricultural measures to reduce water abstraction and consumption for
different environmental conditions or crops and evaluate what might be the most effective measures in different regions.
PROJECT IDEAS
Bernal, J.D. and Fowler, R.H. 1933. A theory of water and ionic solution, with particular reference to hydrogen and hydroxyl ions. Journal of Chemical Physics 1: 515–549.
Berner, E.K. and Berner, R.A. 1987. Global water cycle:
Geochemistry and environment. Prentice Hall;
Englewood Cliffs, NJ.
Blockley, S.P.E. and Pinhasi, R. 2011. A revised chronology for the adoption of agriculture in the Southern Levant and the role of Lateglacial climatic change. Quaternary Science Reviews 30: 98–108. Falkenmark, M. 1986. Fresh water – time for a modified
approach. Ambio 15: 192–200.
FAO. 2003. Review of world water resources by country. Food and Agriculture Organisation of the United Nations; Rome.
Forster, P., Jackson, L., Lorenz, S., Simelton, E., Fraser, E. and Bahadur, K. 2012. Near future drought and food
security in Asia. Centre for Low Carbon Futures;
York.
Garg, N.K. and Hassan, Q. 2007. Alarming scarcity of water in India. Current Science 93: 932–937.
Ghali, E. 2010. Corrosion resistance of aluminium and
magnesium alloys: Understanding, performance and testing. John Wiley and Sons; New York.
Hassan, F.A. 2012. Water management and early
civilizations: from cooperation to conflict. Report
prepared for the UNESCO–Green Cross Inter - national project From Potential Conflict to Co- operation Potential (PCCP): Water for Peace [online]. Available from: http://tinyurl.com/ 6tebpg5.
Hoekstra, A.Y. and Chapagain, A.K. 2008. Globalization
of water: sharing the planet’s freshwater resources.
Blackwell Publishing; Oxford.
IPCC. 2007. Climate Change 2007: Impacts, Adaptation and
Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Parry, M.L. et al. (eds),
Cambridge University Press; Cambridge. Lawson, I.T. 2012. The Holocene. In: Holden, J. (ed.), An
introduction to physical geography and the environment (3rd edition). Pearson Education;
Harlow, 670–699.
McClatchey, J. 2012. Regional and local climates. In: Holden, J. (ed.), An introduction to physical
geography and the environment (3rd edition).
Pearson Educa tion; Harlow, 157–182.
Molden, D. et al. 2007. Pathways for increasing agricultural water productivity. In: Molden, D. (ed.), Water for food, water for life: a comprehensive
assessment of water management in agriculture.
Earthscan; London and International Water Man - age ment Institute; Colombo, 279–310.
Narasimhan, T. 2008. A note on India’s water budget and evapotranspiration. Journal of Earth System Science 117: 237–240.
NCIWRD (National Commission for Integrated Water Resource Development). 1999. Integrated Water
Resource Development: A Plan for Action. Report of the National Commission for Integrated Water Resource Development, Volume I. Ministry of Water
Resources, Government of India; New Delhi. Palmer, M.A. and Bernhardt, E.S. 2006. Hydroecology and
river restoration: ripe for research and synthesis.
Water Resources Research 42: doi 10.1029/2005
WR004354.
Pople, J.A. 1951. Molecular association in liquids. II. A theory of the structure of water. Proceedings of the
Royal Society of London A 205: 163–178. REFERENCES
Richardson, M. 2010. The coming water crisis in Asia. Institute of Southeast Asian Studies; Singapore. Shiklomanov, I. 1998. World water resources. UNESCO;
Milton Keynes.
Shinmura, J. 1995. ‘Machi-zukuri, hito-zukuri to kasen’ (Community planning, people planning and rivers).
In: Ouchi, T., Takahashi, Y. and Shinmura, J. (eds), Ryu-iki no jidai: mori to kawa no fukken o mezashite (The era of river basins: aiming for a rehabilitation of forests and rivers). Gyo-sei; Tokyo.
UNESCO. 2003. Water for people, water for life. UNESCO; Paris.
UNESCO. 2009. World Water Development Report 3:
Water in a changing world. UNESCO; Paris.
Vörösmarty, C.J., Green, P., Salisbury, J. and Lammers, R.B. 2000. Global water resources: vulnerability from climate change and population growth. Science 289: 284–288.
Waley, P. 2000. Following the flow of Japan’s river culture. Japan Forum 12: 199–217.
Waley, P. and Åberg, E.U. 2011. Finding space for flowing water in Japan’s densely populated landscapes.
A INTRODUCTION
This chapter introduces the main components of the global water cycle, describes the main stores and fluxes, and residence times, and presents the underlying physical processes. A discussion on uncertainties in the contemporary water cycle is included. The impacts of climate variability and extremes on the water cycle will cover different time and spatial scales, drawing on evidence from the past as indicative for possible future changes. Specific examples will be provided for North America, the UK, and West Africa. The impact of human modification of the water cycle will be discussed, including a direct role through land
use, and indirectly through a modification of atmospheric composition and climate as a result of anthropogenic emissions of greenhouse gases and aerosols. Finally, this chapter outlines major challenges and unknowns in the global water cycle under the spectre of global environmental change.
B THE GLOBAL WATER CYCLE
The global water cycle is shown in Figure 2.1. Approximately 97% is saline water in sea and oceans (1,338,000 thousand km3), leaving only
3% as freshwater. Approximately half of the freshwater is stored in glaciers and snow (exclud - ing Antarctica, 24,064 thousand km3), and a CHAPTER TWO