There has been a dramatic increase in the number of natural disasters over the past few years,and it is assumed that global warming and climate change could cause even more disasters in the future.Some of the world's leading cities are facing disasters like floods and heat waves.     prefix = st1 /London     London's flood defenses are getting older.Since 1 982,the Thames Barrier has protected the city from the threat of flooding,but it was only designed to last until 2030 and close once every two or three years.About 26 years later the barrier now closes five or six times a year and according to Environment Agency predictions,by 2050 the barrier will be closed on almost every tide if the problem is not addressed.     There are 26 underground stations,400 schools,1 6 hospitals,an airport and 80 billion worth of property in London's flood risk area, so large scale flooding would be disastrous.     Paris     Over a six week period in July and August 2003,more than 1 1,400---mainly elderly people--died in France from dehydration and extremely high body temperature in a deadly heat wave.Heat waves of similar intensity are expected every seven years by 2050,so what can be done to make sure such a disaster does not happen again?     One solution is to have air-conditioners installed in elderly care homes.But this is considered a short-term solution,as the increase in demand for electricity also increases carbon emissions .     InParisthe local authorities are encouraging architects to design new types of buildings  such as the building"Flower Tower,"which uses a covering.of bamboo to act as a natural  air-conditioner.     Shanghai     Shanghai is the fastest growing city on Earth.It has a population of 1 8 million and is only 4 meters above sea level.Sea levels are predicted to rise by 20 cm within the next century. An estimated 250,000 people move to Shanghai every year in search of work, placing extra demands on energy consumption.China relies heavily on coal--fired power stations,but these emissions increase temperatures and,in turn,warmer seas increase the risk of typhoons. What problem should be settled now in London?
How to protect the city's property. Where to build its flood defences. How to use the Thames Barrier to protect the city. How to improve the function of the old flood defences.