By Tania Georgiopoulou
This summer’s repeated heat waves are just a foretaste of what’s to come, according to experts. The average maximum temperature in July, now 33 degrees Celsius (91F), is expected to climb to 41C (106F) in the next decades, and average rainfall levels are forecast to drop by 20 percent or even 80 percent in summer months. Scientists believe that despite efforts by the European Union to limit the effects of climatic change to two degrees Celsius, the average increase will be at least 3.5 degrees over the next few years, with varied effects on different parts of the world. The Athens Observatory’s Group on Energy Planning, Climatic Change and Sustainable Development has studied the effects of climate change in Greece over two years to April 2007. The results show that there will soon be energy shortages, crops will be affected and large coastal areas flooded. Athens will face water shortages. Scientists call for measures not only to avert the phenomena but deal with their consequences.
Frequency of Heat Waves Shows Change
Climate change is no longer seen as a future scenario. In Greece, the first signs were seen last winter and then again in the summer. How these phenomena develop is largely up to us, and depends on the models of growth we choose, which will determine the future increase of greenhouse gas emissions. It is not the heat waves that show the climate has changed, but the frequency at which they occur.
Between 1961 and 1990, Athens had a total of 28 days of temperatures over 40 degrees Celsius. According to scientists’ estimates, between 2071 and 2100, these will total 580-1,078 days, depending on the increase in emissions. The world increase in greenhouse gas emissions (mainly carbon dioxide, which is produced in all combustion processes) by 2100 is expected to be of the order of 62-520 percent depending on what measures are taken to reduce emissions. In practice, this means concentrations of 850-950 parts per million of CO2 in the atmosphere, compared to 380 ppm today. This is a realistic scenario according to the researchers. These emissions will result in an increase of at least 3.5 degrees Celsius in the average temperature and a rise in sea levels of 0.35 to 0.45 meters. These figures refer to climatic change over the planet as a whole, according to figures from the Intergovernmental Panel on Climatic Change (IPCC). The group’s estimates for Greece show a considerable increase in the average maximum temperature throughout the region, but above all in the Balkans, where the average maximum temperature for July is expected to increase by up to 11 degrees Celsius. In Greece, that increase will be from 6.1 to 8.9 degrees Celsius in the southern areas, and from 6.5 to 10.7 in central and northern parts. Lower increases are expected for the months of June and September, to range from rises of 3.9 to 8.9 in the south and 3.4 and 9.9 in central and northern Greece. In Athens, the average maximum temperature in July is estimated to rise from the 33 degrees it is today to 41 degrees Celsius.
Drastic reductions in the amount of rainfall are also expected – about 20 percent, which will be as much as 80 percent in summer months.
In December, the month with the highest amount of rainfall, there will be a considerable reduction, particularly in the Eastern Mediterranean but also in Western Greece, where the average rainfall figures for 2071-2100 are expected to be 60-70 percent lower than at present. In northeastern Greece, however, the islands of the eastern Aegean and Crete, the difference will not be as marked.
There will be even less rain during summer months, particularly in northern Greece and the Balkans, where rainfall is expected to be 20-30 percent lower than today.
“Particularly in parts of the former Yugoslavia, Bulgaria and Romania, the reduction in rainfall during summer months is causing great concern as the rain there feeds the major river systems that flow into Greece,” said Elena Georgopoulou, a researcher in the observatory group.
The average rainfall per month will decrease considerably, particularly in July and August (by 64-77 percent) with the greatest reduction in Athens and the lowest in Thessaloniki. So the future is likely to be much hotter and definitely drier.
“This summer we got a taste of what is to come,” said Georgopoulou. “Imagine July with temperatures over 40 degrees, and occasionally temperatures of around 50 degrees,” added Dimitris Lalas of Athens University’s Department of Physics, who explained that urban populations will want to move to cooler regions. “There will be greater demand for homes on Mt Parnitha, for example, which is 1,000 meters above sea level, and therefore has temperatures that are 6-7 degrees lower.
Effects on Human Activities and Settlements
1. Energy
Energy demands are expected to increase by 5 percent in Greece throughout the year, in addition to what will be needed for growth.
This could rise to 13-23 percent in summer months. Also expected to have a major effect is the reduced capability on the part of hydroelectric stations due to up to 50 percent less rainfall.
At present, the Public Power Corporation operates 15 major hydroelectric projects with a total capacity of 3,017.8 megawatts and plans seven more over the next few years of a total 622 MW. In 2005, the country’s total hydroelectric power output was 5.6GMh, amounting to 10 percent of total power production.
“Productivity at the hydroelectric plants on the Acheloos and Aliakmonas rivers is expected to drop by 30-50 percent,” said Sevastianos Mirasgentis of the National Observatory.
In other places, this percentage is likely to be as high as 70 percent due to reduced rainfall in particular regions. Around places such as Lake Plastiras, however, there is likely to be less of a decrease.
The researchers emphasized that increased demands for power in summer will have to be met, but on the other hand, demand in winter is likely to be lower.
2. Farming
Corn, wheat, cotton and vines comprise 43 percent of farmland in Greece (in Thrace, Macedonia, Thessaly, Epirus and the Peloponnese).
Corn production is likely to be reduced by up to 55 percent between 2071 and 2100 depending on the varieties being cultivated.
As for wheat, there will be a greater range of differences (67 percent reduction to 15 percent increase) as wheat fields often are not irrigated and are affected by drought. Regarding cotton crops, production is likely to vary between a drop of 29 percent to 21 percent.
“It is relatively easy to make changes to farming, such as changing the sowing dates and using different varieties that are better adapted to hotter climates,” said researcher Mary Vitaliotou.
3. Water resources
According to another of the researchers, Ilias Tarnaras, current scenarios regarding temperature rises of 3.5 degrees, will mean Athens will have 50 percent less water than it needs to supply its inhabitants. An examination of the expected changes to the availability of water resources for the Mornos, Evinos and Viotiko Kifissou catchment areas found that annual requirements for Athens are now 400 million cubic meters of water a year under current conditions. The researchers found that the total volume of water will be about 125.4 million cubic meters; and, according to the best case scenarios, could be 202.6 cubic meters. If infrastructure projects are undertaken to allow the use of the water sources in the three catchment areas, the total volume of water available will not be more than 321.5 million cubic meters, that is far less than will be required.
4. Coastal areas
Sea levels are expected to rise by about 60 centimeters according to the most optimistic forecasts, yet scientists emphasize that an increase of one or two meters is not unrealistic. Overall, Greece will lose between 31,000 and 56,000 hectares of its land to flooding. Although a comparatively small area, at local level the negative effects are expected to be considerable. The estimated sea level rises naturally apply worldwide; the effects in each region will depend on local conditions.
In Greece, the deltas of the Evros and Nestos rivers are most likely to be affected, as well as the Thermaic Gulf, the islands of the Pagasitic Gulf, the Amvrakikos Gulf, the Aitolikos and Mesolongi lagoons, the Kyllini Gulf and the islands of Crete, Rhodes, Corfu and Lemnos.
The main effects on the coasts, apart from flooding, are erosion, the increased salinity of river deltas and a deterioration of water quality. Worst-case scenarios that include the melting of the Greenland icecap mean that the sea level could rise by about 7 meters.
(Kathimerini)