(THIS ARTICLE IS MACHINE TRANSLATED by Google from Norwegian)
New Orleans is ravaged and submerged. Bergen is experiencing the rain shower of all time. In Romania, the road network has been washed away by the huge amounts of rain this summer and autumn. At the same time, firefighters are battling the blaze in overheated Portugal. In Japan, a typhoon sweeps across the country, while dozens of lives are lost in typhoons that hit Taiwan and China earlier in September. The reports of extreme weather are increasing – and they are coming from all parts of the world.
When researchers saw Katrina sweep across New Orleans, they could only see that the worst-case scenarios they had worked on came true. Katrina's devastation was in part worse than many thought was possible.
Norwegian scientists have agreed that the climate in Norway over the next hundred years will be warmer and wetter. The wind force will increase somewhat. Depending on the region, the annual rainfall will increase by between five and 20 percent and the temperature will rise between 2,5 and 3,5 degrees. The increase will be particularly inland and in the north.
We will get up to four more days with stronger winds than fifteen seconds. That's the equivalent
stiff to strong breeze.
The rain in Bergen last week is a warning of what's to come, especially along the coast. Western Norway seems to get around fifteen more days a year with over 20 with more rainfall. The increase is over 20 per cent, which is considerably more than the other parts of the country will experience.
Unfortunately, it is probably not the last time we will experience heavy rainfall in this country. New results from the research project RegClim funded by the Research Council of Norway are now available. The results point to the fact that in the next 100 years we will have milder winters in Norway
We will have warmer and drier summers with an increased risk of summer drought in southeastern parts of the country.
There is an increased risk of heavy rainfall everywhere. Along with a warmer climate, increased and more intense rainfall is expected in Western Norway. The wind increases most in the autumn, but the increase is modest. In addition, there is a significant risk that the ice cover in the Arctic may disappear in the summer.
Professor Sigbjørn Grønås at the Geophysical Institute at the University of Bergen is a researcher in this field. When asked whether we tend to exaggerate the terms when talking about extreme weather, we must assume that this is different from normal.
- One must define extreme weather. The Norwegian Meteorological Institute has routines for notifying it
defines as extreme weather. This is when there is a danger that the wind will exceed a certain strength and the precipitation will reach certain thresholds. I believe that their thresholds are trend-setting for extreme weather in our country. Then one can ask whether periods of extreme rainfall or drought are not also extreme weather. The summer of 2003 was extremely hot in Central and Southern Europe. The temperatures over the summer were much warmer than other summers for a period of 150 years with measurements. No matter how one defines extreme weather, it must be in relation to "normal" weather when thresholds are exceeded. But often you do not have good enough measurements or statistics for a long time, says Sigbjørn Grønås.
It is not uncommon for landslides to occur, although landslides are usually triggered by the weather. But this can be both of extreme rainfall and a lot of precipitation over time. There are also some types of landslides, such as large rock slides, which are not so dependent on rain or a lot of wind.
So far this year, 17 tropical storms have swept in from the Atlantic Ocean and across the Gulf of Mexico. Rita, which has now entered the southern United States, is the 17th storm this year, and the Americans expect at least four more this year.
In the last ten years, hurricane activity has increased significantly, and they have also increased in intensity and that precipitation is increasing. Scientists cannot determine that we humans are the cause of climate change, but several suggest that our consumption may be one of several reasons. It is the surface temperature of the ocean that provides energy for the hurricanes. Hurricanes form where the surface temperature of the ocean is above 26 ºC.
In the tropical part of the Atlantic Ocean, the surface temperature has increased steadily over the 130 years that the measurements have been carried out. Especially in the last ten years we have seen an increase. The increase in surface temperature is part of the ongoing global warming, climate scientists point out.
- When it comes to hurricanes in the Caribbean, one knows that the cyclone season started early this year. One has all come to Rita for those who get names. The big question, however, is whether they have been more intense this year and in recent years. This is what many people think. The Americans have good data for their areas since 1950. There are also several cyclones in the Pacific Ocean. One of the reasons for strong cyclones this year is very high sea temperatures. For the Caribbean seas, external meteorological conditions have also been present this year, says Sigbjørn Grønås.
He points out that scientists are afraid that global warming will result in stronger tropical cyclones through higher sea temperatures and more humidity in the atmosphere.
- We know that the sea temperature has already risen as a result of global warming and it will
increase more. Droughts in Portugal and floods elsewhere in Central and Southern Europe have nothing to do with it
tropical cyclones to do. But even such extreme weather can also be linked to global warming. Scenarios for the future for these areas say that there will be more heat waves at the same time as we get a lot of precipitation for a few years. It seems that the summer weather across Europe is becoming more varied. Many believe that the heat in 2003 and the drought and precipitation this year are signs of what will become more common in the future, says Sigbjørn Grønås.
Increase in sea temperature – which only increases slowly – gives more moisture in the atmosphere above sea level. Moisture represents latent heat that is released by condensation. More humidity in the atmosphere provides energy for more extreme weather related to precipitation and wind. I fear this is one of the consequences of global man-made warming.
Many danger signals
The many examples of extreme weather are just some of the climate challenges we face. Sudden storms are perceived as dramatic, while the long-term and slow changes are at least as dangerous.
In Africa, the snow on Kilimanjaro has begun to melt and may soon disappear. More dramatic are the consequences of the snow and ice melting in Antarctica and the melting of the Greenland ice sheet. Global warming will cause sea levels to rise. When the temperature in the sea increases, the water masses will expand so that the sea rises.
The United Nations Intergovernmental Panel on Climate Change (IPCC) concluded in its third main report from 2001 that it is overwhelmingly probable that man-made emissions of greenhouse gases have contributed significantly to the observed climate change over the last 30 to 50 years.