Water & Enviroment
Global temperature changes according to UN scenario A1B

Accepting Climate Change As a Challenge

For water suppliers, this means minimising the “human footprint“ with respect to raw water consumption, linking assets closer together and exploiting new resources where possible

Water will become a prominent topic of the 21st century. In his recent address at the Kuala Lumpur conference in mid-May, IWA President David Garman summarised the crucial challenges facing the water sector on a global scale: the persistent population growth in the developing countries, the dramatic increase in water consumption (especially in agriculture), the progressing deforestation of the tropical rain forests, the increase in nitrogen loads in coastal areas, the further growth of megacities and – last but not least – climate change.

Keeping climate change below the two-degree limit

Today, the climate change phenomenon is basically acknowledged by all relevant authorities and said to be largely resulting from the dramatic increase in greenhouse gas (mainly CO2) emissions into the atmosphere caused by human impact. The recently published 3rd Assessment Report of the Intergovernmental Panel on Climate Change (IPCC)1) also claims that (current) CO2 concentrations in the atmosphere are the highest in 650,000 years. The main culprits are said to be fossil fuels.

The high CO2 concentrations have reportedly caused the earth’s lower atmosphere to heat up by 0.74 °C over the past century, with the last thirty years alone accounting for 0.6 °C! Experts expect a further global temperature increase by 1.8 – 4 °C until the end of the century. Scenarios are based on different assumptions regarding economic development, emissions and population growth.

The United Nations also believe that a further temperature increase cannot be prevented (Fig. 1), but urge that measures be taken to stabilise this increase at least below + 2 °C by the year 2050. This target has also repeatedly been confirmed by the EU 2). “A twodegree limit, of course, doesn’t mean that staying slightly below + 2 °C is just fine and a rise by + 2.1 °C triggers the ultimate catastrophe,” explains Austrian meteorologist and climate researcher Helga Kromp-Kolb from the University of Natural Resources and Applied Life Sciences in Vienna (BOKU).

Most climate scenarios drawn up for a period of 100 years, in fact, suggest that a maximum 2 °C increase in temperature will prevent or at best delay such dramatic events as a Gulf Stream shutdown (resulting in an apparent cooling in Central Europe) or a polar ice melt causing sea levels to rise by as much as 7 metres. More details on how the climate change can be curbed are found under “KLI.EN” on page 10.

Dramatic temperature rise in Alpine region expected

Global models are still fairly wide-meshed and research especially at regional level is needed. But as experts at the “Time to Adapt” Climate Conference held in Berlin in February this year confirmed, there is enough know-how to launch adjustment strategies at European level. Temperatures are expected to increase all over the continent, staying at their lowest on the British Isles (+ 2 – 3 °C on average) and soaring to peak levels with significant seasonal variations (+ 3 – 7 °C in summer) in Central/Eastern Europe and particularly the Alpine region.

Kromp-Kolb gives three reasons why the Alps will be the hardest hit: “Firstly, this region is relatively far away from the oceans that stabilise the climate. Secondly, the temperature increase will cause the snow layer to shrink throughout the year, and this will lead to more sunlight being absorbed and a further rise in temperature. Besides, the area today covered by Austria was particularly affected by the last cold period around 1860 and has not recovered from the latter to same extent as other regions have.”

It was long assumed that in Austria with its highly diverse landscapes, regional variations would also appear within the country. Last June, a three-year research project run by Austrian Research Centers (ARC) finally delivered the hard facts. The results were drawn from the two internationally reputed models MM5 and ALADIN, which the working group chaired by ARC expert Wolfgang Loibl adapted for Austria.

Global data obtained from 100-km grid spacing served to assess the regional climate for the Alpine range using 10-km grid spacing. The period between 2040 and 2050 was investigated. Two of the findings suggest that the most dramatic rise in temperature on a seasonal scale will be in autumn and the number of hot days in the east of Austria will quadruple. For more information visit the website systems research.ac.at/projects/climate

A study on climate change and biodiversity (German title: Klimawandel & Artenvielfalt – Wie klimafit sind Österreichs Wälder, Flüsse und Alpenlandschaften?) presented in early July attempts a holistic forecast for the 21st century. The study carried out by BOKU on behalf of Österreichische Bundesforste AG and WWF reports that back in the 20th century average annual temperatures in Austria already rose by 1.8 °C (2–3 times more than in other areas of the Northern Hemisphere) affecting all altitudes.

Manfred J. Lexer and the co-authors of the study expect a further increase in average annual temperatures in the range of 2.5 °C to more than 5 °C until 2085. Temperatures are expected to increase most significantly in the mountain areas of Vorarlberg, Tyrol, Salzburg and Carinthia.

In the plains, the effect of warming will be 2.5 °C less due to inversion, but is still pronounced. Based on the UN climate scenario A1B, which the authors describe as “optimistic”, the risk of a temperature increase by up to 6.4 °C until the year 2100 cannot be excluded.

It is clear that consistent temperature changes will also influence weather conditions and especially precipitation. Experts expect that water will become even scarcer in the south of Europe and rainfalls will be shifted from summer into winter (resulting in more periods of drought) in nearly all parts of the continent.

During the last ÖVGW conference, water expert Karl Schwaiger from the Ministry of Environment said that even if the total amount of precipitation in Austria were to remain largely constant on an annual scale, there would still be implications on the water balance of rivers and on groundwater recharge.

A hot atmosphere also has a much greater physical ability to store water vapour. Therefore, heavy precipitation, flooding and landslides in large parts of Europe are to be expected.

The glaciers in the (Eastern) Alps, which are contributory to providing fresh drinking water during summer, have lost 52 % of their surface and more than 60 % of their mass as a result of temperatures rising over a period of 150 years (source: “Der Standard”, 7th – 9th April 2007). As this trend is expected to continue and the snowfall boundary is shifted upwards, even less water will be available in summer. Since all large European rivers draw their water from the mountains, flow regimes in many parts of the continent are expected to change.

While the retreat of glaciers is visually compelling to the people living in the Alpine region, the global implications of climate change – on the polar ice caps, the coral reefs protecting the coastal areas, the East African coastal forests and the Amazon rainforest, to name but a few – are much more gloomy. Some 1,700 animal and plant species have already started to migrate to cooler or more elevated regions.

In Austria, the BOKU study identifies more “stress” for pine trees and a decrease in cold water fish habitats by one quarter. The climate change is meanwhile also forcing the human troublemakers to leave their homes. According to United Nations figures, meanwhile 15 million people have become “climate refugees”; if sea levels continue to rise by another 3 to 5 metres, their number will further grow to 200 million!

Adjusting systems to the inevitable

As some of the impacts are already evident and the global climate moreover reacts quite sluggishly, consistent countermeasures to curb the rise in temperature will probably take effect only after decades. An adaptation of the related systems such as energy production by hydropower, inland navigation, flood control and, of course, urban water management is therefore steadily gaining importance.

As for global water supply and wastewater disposal, David Garman believes that taking action against the seasonal or absolute decrease in water supply is of utmost priority. The goal must be to minimise the “human footprint” related to raw water consumption. This can, for instance, be achieved by a cascading use of water, wastewater reconditioning, seawater desalination and rainwater utilisation.

Measures also need to be taken to control the water temperature rise in the supply system leading to microbiological changes, and to improve treatment efforts to eliminate suspended solids, heavy metals and medical residues from water more efficiently. But since water management schemes differ greatly, measures always need to be adjusted to regional conditions. Water suppliers are advised to increasingly pay attention to benchmarking, best practices und asset management.

Last but not least, Garman deplores the fact that water/ wastewater and energy, two closely related infrastructure sectors, continue to be treated in isolation and gives an illustrative example: On a global scale, water distribution devours as much energy as is consumed by Japan and Taiwan together!

ÖVGW President Harald Schneider’s recommendation for water supply managers in the east and southeast of Austria is to incorporate crisis management planning in their thinking and acting. He advises them to draw on support from ÖVGW. To ensure a safe water supply for the population at any time, Harald Schneider suggests the following measures be taken:

  • linking water suppliers and their resources closer together
  • adopting more efficient water use patterns and promoting reasonable water-saving measures
  • exploring new spring water and groundwater resources for a more diversified water supply
  • taking measures to preserve the quality of water even under altered conditions
  • establishing a water tariffs scheme that is attuned to the value of water.

At times when no water crisis is apparent, water pricing schemes are often difficult to comprehend for the public. The ÖGVW President therefore suggests to communicate consistently and openly with the public about the need to make future-oriented investments.
(Source: aqua press Int. 3/2007, Mag. Christof Hahn)

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