Munich Riesling, vintage 2030? - Positive versus negative effects of climate change

Dialogue forum „Munich 2030“ on 15 April 2008

Floods on the Isar in which people in Munich got wet feet have been very much the exception in the past. However, in future, the incidence of flooding is likely to rise in the city, according to Joachim Lorenz, Director of the Department of Health and Environment. He and Prof. Manfred Stock of the Potsdam Institute for Climate Impact Research discussed the effects of climate change at the final dialogue forum in the “Munich 2030” series, on 15 April.

Whilst the future looks bright for wine growers, Stock began by qualifying media reports: “Newspaper headlines predicting vineyards in Alaska are probably exaggerated, although this is very much on the cards for many parts of Canada.” Even now, vines could flourish in cities like Berlin or Hamburg, although the quality might not be of the finest. Turning to the theme of the evening’s discussion, Stock asked: “Why shouldn’t it work in Munich, too?”. During a warm period in the Middle Ages, Germany produced around three times more wine than at present. Stock noted that “temperatures are higher now than they were then”.

According to forecasts by the UN’s Intergovernmental Panel on Climate Change, the average rise in temperature in the period up to 2030 will be equivalent to the increase throughout the whole of the 20th century. After that, the scientists’ projections diverge considerably, since they depend on the level of future CO2 emissions. Even if, as the Council of the European Union assumes, we manage to limit the increase to 2°C in the period up to 2100, this will have drastic consequences for wine growing. Stock forecast “the current Bordeaux region is likely to produce the sort of wines we now associate with Spain and Greece, whilst Bordeaux itself will probably come from Brittany”. Germany stands to gain, as much of the country will enjoy ideal wine-growing conditions. “However, the fate of the current Riesling areas hangs in the balance because temperatures will not fall sufficiently at night to ensure the requisite acidity”, Stock feared.

For Joachim Lorenz, Munich’s Director of Health and Environment, the situation is clear-cut: “Given what lies ahead, we should explore the feasibility of using Munich’s farmland to produce wine in the future”. He anticipates three main problem areas in Munich as a result of climate change: flood control, the sewerage system and urban heat islands. Munich has chosen to pursue a climate-protection strategy, such as a scheme launched in 1987 to subsidise energy-saving measures. Some of the measures implemented have proved in retrospect to be a particularly astute move. For instance, the decision to build such large stormwater retention basins into the sewerage system will pay off if, as expected, torrential downpours become more frequent in the future. Lorenz pointed out that “restoring the River Isar was also originally designed to improve leisure and recreation facilities, but if the work had not been carried out the Thalkirchen area would have been seriously affected by the heavy floods in summer 2005.”

The environmental expert is particularly concerned about two more minor watercourses, the River Würm and the Hachinger Bach since, in both cases, land very close to the banks has been developed. The state authorities are already demanding that the city take action but this is difficult because a number of neighbouring local authorities will have to give their approval, and property owners are resisting moves to publish details of the flood plains.

The city planned to deal with the problem of heat islands by desealing impervious surfaces. Lorenz advised: “This has proved effective at Messestadt Riem, previously the site of the city’s airport, and at many former military installations which are now residential areas or industrial estates.” He referred to the thermal discharge problem, which had prevented power stations from running at full capacity in the record summer of 2003. Caused by lack of cooling water, the solution, he believes, is increased use of renewable energy. Lorenz explained: “The plan is to increase renewable energy’s share to 20% by 2020, either by using our own power plants or by participating in projects outside the city.” 

But what happens if average temperatures in Munich are 2°C higher than at present? Stock noted: “We are not able to make accurate and reliable predictions about extreme precipitation, windstorms and hailstorms”. All the models are subject to a great many unknowns and only show trends, giving no clear indication as to the precise implications for waste-water disposal and flood control.

Furthermore, the effects of climate change are not in linear relation to temperature increases. The climate expert warned: “Once global warming reaches a certain point, it’s a bit like throwing a switch, and the world will face a different situation entirely. Things already look “touch and go” beyond the 2°C mark, and if the most dire predictions are correct and temperatures go up 4°C by 2100, we really will be in trouble.”

Lorenz also appreciates that the position is far from clear. “It’s true that the statistics indicate a rise in flood events because late-spring precipitation, which coincides with snowmelt in the Alps, will increase. But whether or not the systems will also cope with future floods is hard to say.” More precise information will be needed before action can be taken, because huge investments are at stake. Addressing the scientific community, he noted: “We need a detailed forecast for the different areas in Greater Munich.”

According to Stock, four regional models are used in Germany, each of which produces a different result. Comparing the results could provide input for potential changes. To run through the effects of extreme events, experts from the fields of hydrology, geoinformation technology and climate research would have to sit down together. Despite the many uncertainties, the professor has formulated a number of proposals to help the city cope with the effects of climate change. More greening of rooftops, using public parks as auxiliary stormwater retention areas and improving flood controls. 

Lorenz also advocated using geothermal sources. “They have a great future in Munich.” The city has commissioned seismic surveys at suitable locations. Geothermal sources are used in Riem and in the newly developed Freiham district. At Sauerlach, south of Munich, hot water drawn from deep underground can even be used for power generation.

Stock was not optimistic on the subject of climate change and migration. He predicted: “Environmental refugees will be a major problem due to rising sea levels.” As well as Bangladesh, other low-lying coastal regions will be threatened from 2050 onwards, triggering mass exodus scenarios of “biblical proportions”. Moreover, drought will result in a significant deterioration in living conditions, firstly in Africa and then in Asia. Lorenz was concerned that “Munich will doubtless be a major pole of attraction for climate refugees.” However, not much thought has been devoted to this issue as yet, attention so far having largely been focused on the fate of war refugees.

On the other hand, the healthcare system seems well prepared to deal with an increase in infectious diseases resulting from climate change. Lorenz admits however that “the barrage of heat-stress enquiries from the public in the record summer of 2003 severely taxed the city’s resources. New jobs in the environmental medicine department should ease the situation."

Globally, prospects are very gloomy. The World Health Organization believes that most climate-change fatalities will be caused by infectious diseases. Stock, on the other hand, comments: “I'm not sure this estimate is accurate, because there will be a substantial increase in the number of natural catastrophes”. Furthermore, the number of heat-stress deaths should not be underestimated. The exceptional summer of 2003 claimed around 50,000 victims in Europe. Stock believes that “temperatures similar those of 2003 will be the summer norm in the 2040s, and indeed on the cool side in the 2060s.” Will the prospect of a glass of Isar Riesling still seem as inviting?

15 April 2008