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Water resources and climate change

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Water is the primary medium through which climate change influences the earth’s ecosystem. The combined data for average global land and ocean surface temperature shows a warming of 0.85 (0.65 to 1.06) °C, over the period 1880–2012 . Continued temperature variations are projected to affect the availability and distribution of rainfall, snow melt, river flows and groundwater, and further deteriorate water quality. UNESCO states that major threats arising from climate variability and change include droughts, floods, storms, rising sea levels and greater uncertainty in agriculture .

The state of water resources is one of constant change. Rising temperatures are reducing the reliability and quality of water supplies. In Africa, Malawi for example is more susceptible to droughts and prolonged dry spells, Sudan is most at risk of food deficit and is located in a region described of the most vulnerable in the world to droughts. In Asia, Bangladesh heads the list of countries most at risk from flooding, and Vietnam is threatened by rising sea levels. The 2012 World Water Development Report highlights that “under present climate variability there will be greater uncertainty over the boundaries of variation with the possible appearance of new factors, and the presence of thresholds, irreversibility and tipping points”.

Water resources are already stretched for agricultural activity, rural livelihoods and to meet urban demand. On the one hand, 1.6 billion people currently live in countries and regions with absolute water scarcity and the number is expected to rise to 2.8 billion people by 2025 (World Bank, 2013). On the other, the OECD Environmental Outlook to 2050, highlights the baseline scenario projecting a 55 per cent increase in global water demand, from 3500 km3 in 2000 to 5500 km3 in 2050, most of this increase comes from manufacturing, electricity and domestic use. These tensions between existing levels of water scarcity and projections for higher demand confirm the growing water stress accompanied by growing uncertainties due to climate variability and change.

The IPCC Fifth Assessment Report (AR5) confirms that water is an essential crosscutting theme when addressing climate change. The IPCC report (2014) provides new scientific evidence and a major advance about the likelihood of “a detectable human influence on the global water cycle since 1960”. Climate change is happening and will continue over decades and centuries to come, the report states, finding that it is at least “95 per cent certain” that humans are the dominant cause .

The different sections of this Key Issues Guide provide a brief snapshot of three key issues relevant to the state of uncertainties around climate change and water resources: Complex Science, Development Impacts and Water-Energy-Food Security. Climate change adds to the existing drivers of water stress, and challenges our understanding of water security, given the demographic and climatic pressures amongst others. It is also important to take into consideration the different trade-offs that emerge due to the interdependencies between water, energy and food. Accordingly, policy implications for the pressing Water-Energy-Food nexus also deserve attention to address the uncertainties of water security and climate change.
Key resource: Climate change and water: IPCC technical paper VI
Water from tap
M. Ostergaard / Panos Pictures
This report underlines the important roles that water plays in all social, economic and environmental decisions, highlighting policy implications across various sectors, from local and municipal to regional and international levels. It provides an overview of status trends and challenges, moving from raw data to informed decisions, and regional challenges. It also addresses issues around working under uncertainty and managing risk, the problem of undervaluing water, transforming management institutions to deal with change, investment and financing for a sustainable future, and responses to risks and uncertainties, including through mitigation and adaptation to climate change.

Complex Science

abstract water drop smallScientific evidence and complex science represent the foundation and the starting point to identify the interdependencies between climate change and the hydrological cycle. According to NASA, the average temperature in 2013 was 14.6 °C (58.3 °F), which is 0.6 °C (1.1 °F) warmer than the mid-20th century baseline. More...

Development Impacts

Man collecting water smallClimate change and development are inextricably linked, both in terms of impacts and necessary and possible responses. Climate change adds a burden to the question of water stress. Complex science and the IPCC emissions scenarios project higher temperatures to affect all aspects of the hydrological cycle. More...

The Water-Energy-Food Nexus

Agric and water smallWater, energy and food are inextricably linked. Pressures on freshwater are rising – from the expanding needs of agriculture, food production and energy consumption to pollution and the weaknesses of water management. More...

Image credits: MaRS Discovery District | Flickr / Pacific Northwest National Laboratory | Flickr / Timothy Mwaura for CCAFS | Flickr / V.Atakos for CCAFS | Flickr

Latest Documents

The interlinked nature of water security challenges requires comprehensive solutions coordinated among diverse stakeholders
D. Waughray (ed) / World Economic Forum 2011
Water security links together food, energy, climate, economic growth and human security threats. This publication sets out the challenge the world faces if nothing is done to improve water management in the next two decades. In nine c...
Highlighting areas of progress in climate modelling since the IPCC Third Assessment Report
Intergovernmental Panel on Climate Change 2007
Climate models are based on well-established physical principles and have been demonstrated to reproduce observed features of recent climate and past climate changes. There is considerable confidence that Atmosphere-Ocean General Circ...
Extensive summary of climate change impacts illustrating the urgent need to mainstream adaptation into new and existing development programmes
UNFCCC National Adaptation Programme of Action 2007
The result of regional workshops held in Africa, Latin America and Asia, as well as one expert meeting held in small island developing states, this United Nations Convention on Climate Change text outlines the impact from climate chan...
Key messages to COP15 advising on the central issue of water and climate change
Global Public Policy Network on Water Management 2009
With not a single mention of water in the outcome documents of COP13 or COP14, it is of vital importance that water issues be addressed in a manner that befits its importance. This is the reasoning behind the Global Public Policy Netw...
Overview of water-related climate change risks, examining water supply and demand adaptive strategies
A. Nicol; N. Kaur / Overseas Development Institute 2009
This background note, published by the Overseas Development Institute, provides an overview of the potential risks and vulnerabilities that face the water sector due to climate change. It also summarises of some of the adaptive strate...
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Ramy Hanna
This guide has been written by Ramy Lotfy Hanna. Ramy is a PhD student at the Institute of Development Studies (IDS). His doctoral research addresses water security and the political economy of land and water investments in the Nile basin.