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From The Newspaper (18) 　Environment (8)

January 19, 2023

Recently, he watched a TV program which focused on big disasters. One of the episodes that he watched was about 'high flood tide'. Recently, abnormally large typhoons and hurricanes bombarded seaside cities and have caused a lot of damage. Before watching the program, he had vaguely thought that floods happen because of heavy rain, which causes the overflowing of rivers, mainly. He also thought that 'high flood tides' are rare because typhoons and hurricanes don't bombard cities as much, or as often, as heavy rains. But, his understanding was too optimistic. A researcher explained that the rise of seawater happens for two reasons. One, if the temperature of the sea water goes up, the volume of the sea water will simply swell. Two, permafrost has been melting since 1900. So far, the rise of sea water has been about 20 cm since 1900. It is predicted that it will go up 110 cm by 2100 if the temperature goes up by 1.5℃ from 1900 (Now 1.15℃). The researcher emphasized that we shouldn't think that it was just 20 cm or will be 110 cm. The program went on to explain the reasons. Because of Global Warming, sea temperatures have gone up, meaning that the number of typhoons and hurricanes will increase and will become bigger. After typhoons and hurricanes are produced, they are pushed by regular winds, the Prevailing Westerlies, and sometimes they land on cities. Big cities tend to be located on the seaside. Almost all areas have rivers because of rain. Small rivers gather and make big rivers which go to the sea and make big alluvial fans before the sea as the river carries soil. Alluvial fans are ideal places for cities, because they are flat (There are only several meters altitude difference in the place even 100 km apart, the researcher explained.). The researcher explained that alluvial fans are originally easier to subside because of its structure. And some cities use their groundwater for their citizens and factories. (As alluvial fan lands used to be rivers, maybe they have rich groundwater, he guessed.) Because of those reasons, most big cities' lands in the world are subsiding. Tokyo has subsided about 4m so far, New Orleans 5m, Shanghai 3m, Jakarta　4m. He heard that Jakarta is planning to move its capital function to another city, so this subsiding might be one of the reasons. He checked on the internet and learned that traffic jams and air pollution are the other reasons for the future relocation. The program showed a shocking video. It was about the seaside town in Bangkok. There were electricity poles lining from the land to the sea. A person explained that the sea level went up 2m, and the seaside retreated 2km from the place where they started to live. A researcher explained that because of the Trade Wind, Eastern Asia has received the effects of rising sea level the most. After the Thai Flood in 2011, the damage was at the cost of 500 billion dollars. Pakistan's floods happened with the same weather system. He checked on the internet and learned that the reconstruction price tag was also 500 billion dollars. The program showed various cities which have been constructing dikes, and cities which gave up making dikes because they are expensive and/or they spoil the coastal views, and retreated their housing and buildings from the seaside. In any case, to protect cities from high tides will take a huge budget. And, poor countries might not be able to afford that. Probably reducing CO2 is the cheapest way, as a whole, for the world. People in the world vaguely know about this, but human beings don't move unless they feel it's their own problem. He learned that Global Warming makes the frequency of floods increase. So floods happen somewhere every year, but might not occur in one's own country. The frequency of floods in one's own location has changed, for example, from once per 100 years to once per 30 years. But, during this 30 year time period, people forget about the damage done in the previous flood, and lose the incentive to change the situation. It will need a big effort from everyone on the planet to make the necessary changes.

No. 505



*bombard :爆撃する、責め立てる
*permafrost :永久凍土
*the Prevailing Westerlies :偏西風
*alluvial fan :扇状地
*subside :沈下する、陥没する、建物が下がる
*retreat :後退する
*the Trade Wind :貿易風
*dike :堤防