An aquifer is an underground layer of water-bearing permeable rock. Unconfined aquifers are covered by permeable rock and can receive water from the surface whereas confined aquifers lie between two layers of less permeable rocks and are filled with water. There are three different types of aquifers:

  • Porous aquifers of granular or solid rock, whose gaps (pores) water can flow through
  • Fissured rock aquifer of solid rock, which contain fissures and crevasses that provide effective porosity,
  • Cavern or karst aquifer of karstified carbonate rock with areas of karstification which allow water to flow through (i.e. rock corrosion).

The nature of an aquifer is relevant in particular for the production of potable water, the decontamination of polluted groundwater and the influence of mining on groundwater.

Climate index

A climate index is a measurement of the state of and changes in climate change. There are different climate indices, which are based on various calculation models. For example, they simulate global warming, the rise in sea levels or also the frequency of droughts and floods. Indices have the advantage of pooling data for various regions of the world and presenting these in comparisons which leads to, among other things, stimuli for policy development. The Climate Change Performance Index, developed by Germanwatch, for example, compares and analyzes the climate protection performance of 58 states, which together are responsible for more than 90 per cent of global CO2 emissions.

Climate adaptation

Due to global climate change, the living conditions of people and animals are changing, too. Climate adaptation aims to react to the occurrence of changes to the climate by reducing the economic and societal costs of these changes, and even to use climate changes as an opportunity for some regions systematically. Development concepts adapted to the climate that contain urban and spatial planning approaches that are adapted for rising sea levels and weather extremes are one example for this.

Climate change

With industrialization and the accompanying increase in greenhouse gas emissions like CO2 due to the combustion of fossil fuels, all people influence the natural greenhouse effect of our planet. The increased concentrations of greenhouse gases in the atmosphere mean that solar radiation reflected from the earth can be radiated back into space to a lesser extent. This leads to global warming for which humans are responsible. The rising average temperature allows us to observe the melting of the polar icecaps and glaciers, which in turn results in higher sea levels, extreme weather and progressive desertification.

To fight the harmful effects of climate change, two models have emerged: On the one hand, a mitigation strategy, which concentrates on fighting global warming itself, on the other an adaptation strategy, which designs spatial planning approaches appropriate for climate change.

Climate conferences

Researchers in the 1970s already recognized the threat brought by climate change, which led to the first climate conference being held in Geneva in 1979. The first international climate protection agreement, the Framework Convention on Climate Change was adopted in Rio de Janeiro in 1992. Since 1994, annual UN climate conferences have taken place. The Kyoto Protocol agreed in 1997, represents an important step for the international climate conferences, as it set out binding obligations on the signatory countries to reduce their greenhouse gas emissions.

Climate conflicts / climate wars

The theory of climate wars describes the danger of future violent conflicts which arise as a result of climate change leading to ever scarcer resources and foodstuffs production. It is assumed that climate change will lead to additional environmental stress and societal crises, for example in the Sahel, which is characterized by weak states, civil wars and large flows of refugees. The concept of climate wars is, however, controversial, as it provides little empirical evidence for the links between scarcity and the occurrence of conflicts. Former UN Secretary-General, Ban-Ki Moon identified the Darfur conflict in Sudan as the first example of a conflict for ecological reasons.


The term climate-induced refers to the change of certain conditions due to changes in climate. Examples of this are the naturalization and spread of non-domestic organisms such as increasingly widespread mosquito species in more northern areas, or also the more frequent occurrence of extreme weather conditions such as tornadoes and hurricanes.

Climate mitigation

Climate mitigation aims to minimize the extent of climate changes using strategic measures and in so doing, to mitigate the loss of glaciers, rising sea levels, increase of extreme weather and other presumed effects due to global warming. Climate mitigation includes measures to reduce greenhouse gases such as CO2 certificate trading or supporting climate-friendly technologies.

Climate scenarios

So-called climate scenarios are the basis for the development of strategies that deal with climate change. These are scientific models that are based on different calculations and that simulate the expected climate changes (such as changes to temperature, precipitation, wind, sea levels). In contrast to a weather forecast, climate projections do not aim to predict the state of the weather in a particular place at a particular time. Instead, they calculate statistical averages across larger areas and periods of time, such as the development of the global average temperature.

CO2 certificate trading

The Kyoto Protocol, which came into effect in 2005, marked the first time that the international community agreed to be bound by specific targets aimed at reducing greenhouse gases harmful to the climate, first and foremost carbon dioxide (CO2). By 2020, the European Union would like to reduce its greenhouse gas emissions by 20 per cent in comparison to the base year of 1990. In this respect, the EU introduced the emissions trading system (EU ETS), which ties the production of CO2 to certificates. It functions on the principle of “cap and trade”. An upper limit (“cap”) is set by the EU to determine what quantity of greenhouse gases a company is allowed to emit in a specific period of time. The state issues a certificate to companies, free of charge, for exactly this amount per tonne of CO2. If a company wants to produce more CO2 than the certificates it has received, it must buy-in further rights at auction or on the market. That means that vice versa, companies that have not used their certificates can trade these.


A dam is a structure to hold back (dam) rivers into a suitable valley. Due to their reputation as a sustainable and environmentally friendly power-generating model, their number has increased significantly in the last few decades. However, the very issue of environmental protection is highly controversial. Besides the massive intervention in the natural landscape and the effects on native species, research has called the environmentally friendly power generation of dams in particular into question. It is estimated that around four to seven per cent of methane emissions worldwide can be traced back to water reservoirs.

Environmental conflicts

The term environmental conflict is often used synonymously with climate conflict. Environmental conflict can, however, be conceptually separated from climate conflict as it explicitly involves conflicts that arise for environmental reasons while the causes for conflict in a climate conflict arise due to problems caused by climate changes. For example, an environmental conflict can occur due to conflicting interests about the use of environmental resources such as a lake, which can escalate into a violent conflict. While climate conflicts currently constitute a contentious hypothetical concept, environmental conflicts are already real, existing, observable disputes about diverging environmental interests.

Environmental refugee

Environmental refugees are people who leave their homelands because of environmental destruction or scarce resources. The term is attributed to a UN Environment Programme report in 1985, in which environmental refugees were defined as people who are forced to temporarily or permanently leave their traditional habitats due to heavy damage to the environment which threatens their existence and/or severely compromises their quality of life.

At the moment, there are no reliable figures or studies on environmental migration. As a result of the effects of climate change, but also due to the rapid growth of the global population and the accompanying regional shortages of resources, it is assumed that there will be an increased number of environmental refugees in the future.

Integrated water resources management

The concept of integrated water resources management (IWRM) was already adopted as an international guiding principle at the International Conference on Water and the Environment (ICWE) in Dublin in 1992 and in the United Nations’ Agenda 21.

The aim is a sustainable management of bodies of water and aquifers to promote social and economic development and at the same time ensure the functionality of ecosystems. This incorporates ecological, economic and social challenges in the collaboration between state, societal and private industry actors.


The Intergovernmental Panel on Climate Change (IPCC) was founded in 1988 by the United Nations Environmental Programme (UNEP) and the World Meteorological Organisation (WMO) as the international body to collect and analyze scientific research on climate changes for political decision-makers and interested parties. In this respect, the IPCC does not itself carry out any scientific research. Results are summarized in the so-called assessment reports and form the basis for the global debate on climate policies. In the most recent Fifth Assessment Report current research findings on the causes, effects and future projections of global warming are presented and summarized for political decision-makers.

Land grabbing

The term land grabbing refers to the acquisition of large areas of agricultural land in developing countries by international agricultural companies, private investors and state actors from industrial and emerging countries by means of long-term lease or purchase contracts. The land is mainly used to grow food or energy crops for export to the investing countries for food and energy security. Other motives of foreign investors are securing sources of freshwater and natural resources.

The negative tone of the term land grabbing can be traced back to its negative effects, such as the destruction of small farmers’ livelihoods, a lack of food production for local populations, low wages for local workers or large-scale environmental degradation, for example by monocultures with intensive use of pesticides and mineral fertilisers.

Rising temperature

According to current data, 2015 will be the first year in which the global average temperature will be one degree higher than in pre-industrial times. The long-term level and the effects of the rise in temperature are not yet foreseeable and are strongly linked to global climate protection efforts. The effects of rising temperatures are more frequent extreme weather events such as heatwaves or violent storms, rising sea levels, which result in the flooding of coastal regions or also mass extinctions of fauna and flora. Limiting the rise in temperature to two degrees Celsius by means of sustainable climate policies is an international target. Climate change impacts up to this threshold are considered to be controllable.

Rise in sea levels

Global sea levels have only been measured exactly since satellite measurements allowed it in the early 1990s; the first level measurements on coastlines had already been recorded since the 18th century. The evaluation of the measures showed that sea levels have risen significantly. Due to climate change, a significant increase in sea levels is expected. Estimates of the exact height of this rise, however, differ. Just under two-thirds of the rise are to be traced back to the thermal expansion of water, the rest of it to the influx of melting waters from the mainland. A rise in just one metre can already have an enormous impact on ecological systems and the inhabitants of coastal areas. Among the consequences are coastal erosion, salinization of coastal waters and flooding as well as the potential increase of devastating natural disasters such as for example, tropical storms.

Soil degradation

Soil degradation (also land degradation) is understood to mean a deterioration or even the loss of soil. Worldwide, an estimated 5 to 10 million hectares of fertile soil are lost annually, for example, due to erosion and salinization. Against the background of 90 per cent of global food production being directly dependent on fertile soil, and increasing demand for foodstuffs from an ever-growing global population, it is imperative that this resource be handled sustainably. Significant processes that lead to soil degradation are, among others, erosion by wind and water, the use of impervious surfaces, compaction as well as salinization and acidification.

Transboundary water resources management

As a scarce resource, water requires cooperation mechanisms, especially in the case of transboundary bodies of water, to agree on rights of disposal, acceptable regulatory mechanisms and joint means of decision-making between riparian states. In this respect, mutual dependencies on the transboundary water resources must be respected to prevent environmental issues and resource conflicts in the future.

Examples of supra-regional water resources management are interstate collaborations in relation to the Aral Sea or the Nile Basin Initiative as a platform for dialogue on the use of the waters of the Nile.

Virtual water

Virtual water describes the quantity of water used to produce a product or service. This encompasses the water consumption throughout the complete production chain: From the cultivation and harvesting of natural resources via the subsequent processing to the final manufacturing of a product. In this respect, the quantity of water can be very dependent on the region. While the cultivation of certain field crops and types of grain in tropical and subtropical countries requires a lot of water due to the hot temperatures and intense sunlight, the same crops would require less water in European countries due to the temperate climate. Sustainable and efficient production, therefore, aims to use the smallest possible amount of virtual water.

Water availability

The availability of water depends on water resources and water extraction. The United Nations refers to water availability as the available freshwater resources, that is the quantity of freshwater that one person has available per year.

The climate and climate change have different effects on water availability depending on the region. There is a tendency for dry (arid and semi-arid) regions to become drier in the future and damp (humid) areas to become even wetter. It is assumed that therefore more people will suffer from water shortages in the future (see water stress).

Water resources

More than 97 per cent of the total supply of water on earth is salt water. A mere 2.5 per cent of water resources are freshwater, of which, however, about two per cent is ice at the polar caps and in glaciers. Also, the freshwater supply is unevenly distributed around the world and without special treatment, the largest share of water resources, salt water, cannot be used. While, for example, in Kuwait 10m3 are available per person per year, in Germany it is 2,000m3 and in Austria 10,000m3.

Water scarcity

In numbers, water scarcity means that a country has less than 1,700m³ of water available per year for one person. Water shortage occurs at under 1,000m³.

As well as the quantity of available water, water scarcity also includes the quality of the water and sanitation. The occurrence and increase of water scarcity can be a consequence of climate change in some regions. It is assumed that in particular developing countries that are already dealing with scarce water resources and rising populations will be affected. Resulting from this is a direct link between climate change, water shortages, and conflicts relating to the scarce resources. Different concepts to counter the irreversible reduction of water resources and a sustainable, cooperative way to deal with these, such as integrated or transboundary water resource management, are being developed (see above).

Water stress

If water extraction exceeds a certain percentage, we call it water stress. Extreme water stress, therefore, occurs if more than 40 per cent of resources are extracted. Due to the globally unequal distribution of water resources, about 2.3 billion people currently live under extreme water stress. Due to climate change and the rapid growth of the population, particularly in the developing world where there is already little water availability or quality, it is assumed that in the future more than twice as many people will live under extreme water stress. Presently, the regions of Sub-Saharan Africa, south-west Asia and the Mediterranean are suffering the most from water stress. To mitigate the effects of this development, more water-efficient production methods and treatment technologies are being developed.

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