Chapter 2 Mounting Evidence, Emerging Responses

2.1 Changing Climate, Changing Waters

The evidence

Climate change is here, and will be with us for the long-term. For at least the next few decades the planet is set to experience an increase in temperature and change in rainfall patterns. There are no mitigation plans on the horizon that will have more than a slight delaying effect on the process of planetary transformation that has now begun. The empirical evidence for this is already mounting. To date, most attention has been given to the temperature dimension of climate change – which explains why the threat has become popularly known as global warming. While it is truethat the direct effect of the heat-trapping gases is on global temperature, however, the consequences of a warmer world will be greatly amplified in the response of the world's water. We are faced with nothing less than a great destabilization and reshuffling of the world's hydrological systems.

Although we know that large changes are afoot, we do not know precisely how great they will be. The magnitude and pace of change will depend in large part upon what happens to the global emissions of greenhouse gases. If atmospheric concentrations of greenhouse gases can be stabilized at 550 parts per million (ppm), projections indicate a global mean temperature rise of 1.9 to 5.1 degrees Celsius above the 1990 average by 2100. Stabilization at 750 ppm, however, will lead to an increase of 2.8 to 7.0 degrees Celsius. As a comparison, global mean temperatures increased over the last 100 years by 0.5 degrees Celsius and the current level of CO2 in the atmosphere is 350 ppm.1


The projections further indicate that warming will vary by region, and will be accompanied by both increases and decreases in precipitation, depending on region and locality. There will also be changes in the variability of the climate, including rainfall and snowfall, and an increase in the frequency of some extreme climate phenomena, such as floods and droughts. The amount of warming will be greater towards the poles and in the continental interiors, and less over the oceans. More heat in the atmosphere will cause more evaporation from water surfaces and transpiration from vegetation, resulting in greater amounts of moisture in the air.

This destabilization of the world's hydrological systems will be manifested in many different ways. A number of global or large area generalizations have been made recently by the Intergovernmental Panel on Climate Change (IPCC) – the leading international source of expertise. In its Third Assessment Report published in 2001, the Panel concluded that annual precipitation would increase in high and mid-latitudes and most equatorial regions, but would generally decrease in the subtropics. The Panel also projected alterations to the seasonal distribution of precipitation, with the likelihood of more rain, less snow, and higher evaporation as temperatures increase. Rainfall intensity and variability is expected to increase in many areas.


At the Regional Dialogue on Climate Change, Water and Wetlands in Southern Africa, held in November 2002, participants discussed the region's high sensitivity to current climate variability, particularly drought. Managing water scarcity is the predominant challenge. Long-term observations suggest that temperatures have increased 0.5°C over the past 100 years, that the seasonality of rainfall is changing, and that annual flows of some rivers such as the Zambezi are declining. Droughts appear to be increasing in frequency and severity.

At the same time, the region is starting to experience intense flooding, a phenomenon that is inconsistent with the long-term climate of the region. Between 1999 and 2002, the region was hit by a series of intense rainfall episodes including tropical cyclone Connie that produced the worst flood in 50 years. Two weeks later, tropical cyclone Elaine further inundated the region, causing extensive flooding in the Limpopo River Basin. Such an event is supposed to occur only once every thousand years. The overall conclusion is that Southern Africa is facing more and more climate variability.

These changes are consistent with the climate change projections of the Intergovernmental Panel on Climate Change. With a projected warming of 1.7°C over the next one hundred years, rainfall in the region is expected to decrease by 5 to 20% in all the major river basins. Increases in evapo-transpiration are expected to result in losses of run-off in all the major river basins of the region. The most severe impact are expected in the Ruvuma River Basin in Tanzania and Mozambique and the Zambezi River Basin, whose resources are shared by eight countries - Angola, Botswana, Malawi, Mozambique, Namibia, Tanzania, Zambia and Zimbabwe.

With demand for water in the region expected to increase more than 90% by 2020, meeting these needs will require a major investment in resource development and management. When the current and projected trends of climate change are added to the equation, the situation appears daunting.

The impacts

These changes are already having an effect. In many places mountain glaciers are shrinking, and mountain snow cover is decreasing. This is likely to decrease the volume of spring and summer flow in rivers fed by snow and ice melt, and increase the winter flows. River basins where this is happening include the Rhine and the Rhone in Europe.3 In tropical regions, such as the Andes and Mount Kilimanjaro, a dramatic melting of glaciers has already occurred over recent decades and is likely to affect downstream livelihoods sharply. Since water is more in demand during the growing season, the shift in seasonal flows can be expected to have an adverse impact on downstream water users. Irrigators will probably face shortages at critical periods. Hydropower operators will be affected by the changes in the quantities of water available, especially during periods of drought and high power demand.

Forecast of the IPCC on global temperature rise

In Arctic regions the warmer temperatures have already resulted in the thawing of permafrost and the unseasonably early break-up of ice on rivers and lakes.1 These changes impede road transportation that depends on a frozen surface, cause the destabilization of natural ecosystems and soils, and damage buildings and public infrastructure. Other consequences of climate change include the lengthening of high-latitude growing seasons and shifts in plant and animal ranges, including those of insects and disease vectors.1 Such changes have serious implications for water quality and seasonal water availability.

The uncertainty

The climate of the past can no longer be regarded as a reliable baseline from which to forecast climate variability and extremes in the future. Extrapolations from observed data are becoming increasingly unreliable. This suggests that the data and assumptions on which water use has been planned and managed in the past can no longer be regarded as valid for the future. Unfortunately, the general indications of climate change and its impacts are as yet insufficiently precise to be a reliable basis for changing current day-to-day water management decisions.

Drought in India

Devastation from extreme river flows, Southeastern USA

With higher temperatures and greater humidity destabilizing the global atmosphere and the hydrological cycle, weather patterns are set to become increasingly difficult to predict. There is considerable uncertainty about the rate and even the direction of change at the regional and local level. Global warming does not mean that the same degree of warming will be experienced everywhere. Some places may become cooler. The same applies to snowfall and rainfall, with some areas becoming drier, in spite of the global trend towards more precipitation.1


It is unlikely that more precise information about changes in water availability will become more accessible in the near future. Information on the frequency and magnitude of floods and droughts or on variations in stream flow or groundwater recharge are not derived from or coupled with current climate models. Unfortunately, neither the extrapolation of recent trends nor the downscaling of global models can produce the precise information that water planners, managers and users would like to have access to.

The difficulty in applying global models at a regional level lies in the scale mismatch between global climate models and catchment hydrological models. Climate models use a monthly time step at a spatial resolution of several tens of thousands of square kilometres. Catchment and water management models, on the other hand, require data on at least daily scales and at a resolution of perhaps a few square kilometres. Although different hydrological models can give different values of stream flow for a given input, the greatest uncertainties in the effects of climate on stream flow arise from the uncertainties in the climate change scenarios themselves.

The more we find out about climate change and the impacts on water resources, the more unknowns we will recognise. What to expect is a kind of uncertainty that increases with the growth in knowledge. The challenge facing the water management community is therefore less about adaptation to specific climate changes, and more about adaptation to the added uncertainties being created by climate change.

2.2 Adaptation to Climate Change

The perspectives

The United Nations Framework Convention on Climate Change (UNFCCC) has as its ultimate objective "the stabilization of greenhouse gas concentrations in the atmosphere at a level which is not dangerous to the climate system"- a goal often referred to as "mitigation."4 Since the reduction of greenhouse gas emissions is proving to be a difficult process, it is becoming ever more clear that mitigation alone will not be sufficient to protect societies from the effects of climate change. It is now recognised that adaptation has a major role to play in reducing the impacts of climate change on people, businesses and society at large.


The consensus of the Mediterranean Dialogue on Water, Wetlands and Climate Change, held in December 2002, was that climate variability will increase in the future. Current pressures on water regimes will intensify, leaving little room to manoeuvre, especially in drought situations.

Morocco and Tunisia are particularly susceptible to drought, and increasing climate variability is expected to exacerbate water scarcity, soil erosion and wetland degradation. In Cyprus, where rainfall has decreased 1 mm/year over the last century and mean temperatures have increased by 0.5°C, water availability has gone down by 40% from the estimates made in 1970. In the water scarce regions of Turkey, climate change threatens to accelerate desertification. In Tunisia, studies to develop water resources assume a stable climate. The key challenge, therefore, is to incorporate climate change assumptions into current water resources planning. In France, climate change models for the Rhone Basin project more severe floods in autumn and winter and more marked drought periods.

In the Mediterranean, the sector most likely to be affected by climate change is agriculture, since that sector utilizes a high proportion of the available water resources. At present there is a delicate balance between water supply and demand in relation to agriculture. Climate change threatens to destabilize this. Changes in water regimes are likely to go beyond the limits of recent experience in terms of quality, quantity, variability and extreme events. The changes that will occur are likely to vary greatly even over relatively short distances. A key challenge for the Mediterranean is to address this uncertainty in water resource planning and management.

Rising costs of loss in assets due climate related events

Adaptation in the context of climate change is defined by the Intergovernmental Panel on Climate Change as “the adjustment in natural or human systems in response to actual or expected climate stimuli or their effects, which moderates harm or exploits opportunities.”1

Adaptation may be categorized in a variety of ways, with a distinction often being made between planned and spontaneous adaptation. Planned adaptation is a process of public policy making and preparation that is based on an awareness of the existing conditions and vulnerabilities, the attributes that will change and the actions required to minimize loss or optimise benefits.5 Spontaneous or autonomous adaptation is often referred to in the context of businesses adapting to change, usually triggered by markets or welfare changes and societal preferences.5 Planned adaptation therefore refers primarily to governments working in a more pro-active manner, while spontaneous adaptation emphasises the role of the private sector, often taking a more reactive approach.

Those who favour deploying “concrete” adaptation measures, such as the creation of reservoirs or development of irrigation systems, have sometimes been reluctant to embrace “softer” adaptation methods such as education, extension services, regulations, penalties and other incentives. In fact, both approaches have their advantages. Given the pervasiveness of climate change, there is a role for adaptation at all levels of social organization, from national and local governments to the private sector, civil society and individuals and households.

Discussions on adaptation also differ from sector to sector. In the public health field, adaptation measures are generally referred to as “prevention”. Prevention can be “primary”, in which the disease vectors themselves are attacked or controlled, for example in the case of malaria eradication or vaccinations. It can also be “secondary” when referring to steps taken to reduce the risk of exposure to a particular illness or disease. Such “secondary” prevention might include the use of mosquito nets or measures to ensure safe sources of water supply.

In coastal zone management the three-fold approach to adaptation of “protect – accommodate–retreat” is widely used. Protection refers to the building of coastal defences such as sea-walls or dikes. Accommodation is focused on the harmonization of coastal land use with storm hazards and sea level risks, for example through land-use and building regulations or warning systems. Retreat is conducted when people abandon land in the coastal areas and leave it to the sea, for example when creating a coastal zone nature reserve6


One of the main findings from the recent Central American Dialogue on Water & Climate, held in November 2002, is that the impact of climate change on the region's water resources will threaten all sectors of society, especially the poorest and most vulnerable. The Central American region is particularly susceptible to natural disasters. Although it contains less than ten percent of the total population of Latin America, it has suffered more than half of the wider region's disaster-related casualties since 1960. From 1960 to 1999, the total number of people who died due to disasters in Central America totaled almost 60,000, with another 125,000 people injured, and over ten million made homeless or displaced. Nearly half of these people were the victims of climate-related disasters. During the same period, the accumulated economic cost of these events is estimated to have exceeded US$15billion. Water professionals need to initiate concerted efforts to reduce the vulnerability of the region to climate-related disaster and climate change.


The Mekong River Basin is utilized for a variety of economic activities, from fishing and subsistence farming to intensive rice cultivation. At the Regional Dialogue on Water, Wetlands and Climate Change in the Mekong River Basin held in December 2002, participants concluded that climate change is likely to trigger significant alterations in the pattern and distribution of rainfall over the entire basin. Seasons will shift, with the dry season lasting longer and experiencing even less precipitation (except in the Mekong delta), and the rainy season starting earlier. The upper Mekong in southern China is expected to receive 20% less rainfall, while the Korat Plateau in the middle Mekong may see a 10% increase. The Eastern Highlands and Lowlands are expected to receive the same overall amount of rainfall, but with significant changes in month-by-month precipitation levels. Temperatures are expected to increase from 1 to 3°C over the next century.

Reduction of rainfall in the upper Mekong in southern China will affect subsistence and commercial farming. Changes in rainfall patterns could alter flooding regimes, which may in turn affect ecosystems such as the flooded forests in Vietnam and elsewhere. Mangroves and brackish water fisheries in the Mekong delta are likely to be affected by changes in ambient salinity. Severe floods are expected to threaten the heavily urbanized lowland areas of the Mekong.

Rice cultivation, the main source of food in the region, will be strongly affected by changes in the hydrological cycle triggered by climate change. Seasonal shifts in rainfall may have a strong impact on crop yield and crop cycles. The generally shorter and more intense rainy season could make varieties of rice and other crops currently cultivated unsuitable. Some of the low-lying land may have to be abandoned if the level and duration of flooding affects crop survival or productivity.

When discussing adaptation to water management, a distinction is often drawn between supply-side options, such as increasing storage capacity or extending water delivery services, and demand-side approaches, which might include reducing water use and fixing leakages. Seven categories often used in the natural hazards field could also be applied when considering climate change adaptation in the water sector. These categories offer a checklist of potential adaptation options. The categories are:

Recent discussions on adaptation to climate change have mostly emphasized specific adaptation measures. In agriculture, proposed measures include providing more irrigation water, changing crop varieties to drought resistant or heat tolerant ones, and modifying cultivation practices. Other measures discussed include drip irrigation and the installation of water-saving devices to reduce the quantity of water used for domestic purposes. Yet other means include limiting flood plain development to areas higher than the 50 or 100 year flood frequency line or increasing public expenditure for the detection of leaks in water supply systems. These and other specific measures are the means whereby specific policies can be implemented.

So far little attention has been given to developing policies and determining the strategic directions for adaptation in the water sector. Adjusting existing policies and planning approaches in the various sectors is crucial, however, if adaptation to climate change is to take place.

A way forward

What are the advantages and deficiencies of the presented adaptation approaches when applied to water management? Much of the discussion on climate change mitigation and adaptation has focused on a top-down approach and relatively neglected local and regional perspectives and capacities. The planned adaptation approach will require a significant capacity for policy-making and management innovation. Unfortunately, many countries do not have the required expertise and resources. Particularly in the least developed countries, such capacities are only weakly developed. A top-down approach is thus unlikely to gain wide support.


Since the drought of 1877, Brazil has developed policies to address the impacts of climate variability, especially for its semi-arid regions. Over time these policies have evolved from short-term relief efforts to more complex approaches. Short-term relief has focused on maintaining the income levels of the rural unemployed population through public construction works. In addition, water distribution through trucks and the importation of food supplies have helped people to overcome the immediate impacts of drought. Longer-term measures have focused on building hundreds of dams to increase water storage capacities by several billion cubic metres. The creation of storage is an example of a classic approach to dealing with variability of rainfall and perennial water courses. The limitations of the approach are becoming apparent in already over-allocated systems and where environmental and social concerns over dams are high.7


At the Regional Dialogue on Water, Wetlands and Climate Change in West Africa, held in November 2002, participants concurred that the 1970s marked a turning point for the region in terms of water resources availability. Since that time, rainfall has decreased across the entire region, with the largest declines in the north. Several large river and lake systems, including the Sokoto River system in northwestern Nigeria, have suffered significant reductions in river flow as a result of lower rainfall and higher rates of evapo-transpiration.

According to the Intergovernmental Panel on Climate Change, West Africa is projected to experience about a 1°C warming over the next 50 years. Climate change may substantially affect irrigation withdrawals because of higher temperatures and greater evapo-transpirative demand greater evapo-transpiration. The success of rain-fed agriculture in the region depends much on the onset and cessation of monsoon rain. There is great deal of uncertainty about how climate change will affect monsoon dynamics. In a majority of West African countries, river run-off is expected to decrease, as is the amount of water available for activities downstream of dams. Many vector-borne diseases that are prevalent in West Africa, such as dengue and malaria, are expected to increase their geographic range.

Floods contaminate downtown Franklin, VA with oil

In recent decades, increasing awareness about the role of natural hazards, the risks they pose and their potential economic damage has led some countries to improve their planning. However, considerable time and resources are often needed to develop these plans. In France, a decade of risk zoning at the community level has resulted in 30% of at-risk communities now having an approved plan in place. Meanwhile, in Bangladesh, 15 years of flood and drought risk planning has not significantly reduced the actual risks to the most vulnerable. Even if an integrated planning process is established, it might take decades to develop such plans to a satisfactory level, and still longer to implement them. Technical and financial constraints often hinder more rapid progress and institutional and political obstacles can take years to overcome.

Progress with autonomous adaptation, driven largely by the private sector, has also been slow. As with public water managers, businesses have only started to look at climate change in a piecemeal way over the last five years. Thames Water in the UK has conducted some studies on the water availability in its concession areas, as many of its investments have a time horizon of several decades. Re-insurance companies like Swiss RE and Munich RE have also carried out extensive studies to better define future risks. However, the actions of these large companies contrast sharply with a lack of attention from other larger and smaller companies in the water sector. Though many options for adaptation exist, it is not yet apparent whether a widespread “autonomous adaptation” will simply emerge without some sort of external catalyst.


Experiences in other policy areas, such as health, education, and agriculture, demonstrate that success in adopting new ways of working does not lie exclusively with either the public or private sectors. Civil society also has an important role to play. While the private sector clearly forms a part of this group, the collective efforts of various stakeholders from civil society can often contribute significantly to establishing innovative practices. Recent extreme weather events illustrate some of the many ways in which civil society can contribute to adaptation. Participation in dike surveillance and protection squads, individual assistance to flood victims or the organization of food parcels during droughts demonstrate how civil society can play a critical role in adaptation to climate change. Strict top-down or bottom-up approaches are clearly not the answer.

What is needed is a new approach that would be characterized by flexibility and building adaptive capacity in the face of uncertainty. It would draw on existing approaches, techniques and expertise to create a new blend of strategies, styles and means to innovate and implement concrete adaptation measures. It would represent a middle way between planned and top-down technocratic management and the more laissez-faire reliance on spontaneous actions. Adaptation in this sense would be used to strengthen more progressive elements in the water sector. The new threat of climate change and its attendant uncertainties would thus help to propel innovation, and make the required changes more visible and salient. In this way it would support the changes that are occurring in the water sector at present and create opportunities for taking a more integrated and sustainable approach to water management.

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