What is the harm of greenhouse effect?

The greenhouse effect caused by the increase of carbon dioxide content in the atmosphere is a hot topic in recent years. Scientists believe that in the next 50 years, the global temperature will rise by 2℃ ~ 8℃! This is the highest rate of global warming in ten thousand years. What is the impact of global warming on human beings? Although opinions vary, most scientists believe that it will bring disastrous consequences to mankind.

Changes in living environment

Global warming will make mankind helpless to the deterioration of its living environment. Because the polar ice will melt in large quantities, the sea level will rise significantly. If the greenhouse effect is not controlled, by 2050, the world sea level will rise by 40 cm ~ 140 cm, and it is not impossible to rise by 3 m ~ 4 m What does this mean? Undoubtedly, it was an unimaginable scene: several major deltas such as Ganges, Nile and Mississippi will be submerged in the vast ocean; Island countries in the Pacific Ocean and the Indian Ocean will cease to exist; Sea water will also overflow 30% of Tokyo, Japan; Skyscrapers in new york, USA, and coastal areas such as China and Hongkong are also doomed. In Bangladesh, 10000 ~ 2000000 people lost their homes; Holland near the North Sea will disappear from the earth. ...

The above situation is neither alarmist with ulterior motives nor fickle fiction by poets and writers, but a warning issued by more than 300 scientists from more than 20 countries at international conferences a few years ago.

1987, a large piece of ice (25×99 miles) fell off the Antarctic ice area and washed into the Ross Sea, so the outline of the Antarctic coastline was changed and the beautiful whale bay disappeared, leaving only the memory of the cartographer. As we all know,13 of the world's population and most cities are located in coastal areas and river estuaries, and 20 of the 35 largest cities in the world are located in coastal areas. Large-scale population migration is undoubtedly a disaster. At that time, people from southern China may move to Siberia in droves, and nationals of many other countries will also move to Canada, and the population of Canada will increase from 20 million to 200 million ... What is even more worrying is that the "flood" caused by sea level rise may be sudden and unpredictable. American experts have warned that new york will disappear from the earth within 20 years, and the waves that flooded new york may come without warning, flooding new york and its adjacent coast, causing millions of people to die at the bottom of the sea and incalculable loss of life and property. They also said that this speculation is based on the collected data, because the sea level in the Atlantic Ocean is rising at an alarming rate.

Changes in economic life

Although global warming is beneficial to agriculture in some high-latitude rich countries (such as Nordic countries and the former Soviet Union), most parts of Asia and Africa will be extremely hot and dry, which will bring great disasters to world agriculture. According to a three-year survey by British and American scientists, by 2060, global warming will reduce the world grain output by 1% ~ 7%, and the biggest reduction will be in developing countries near the equator. Due to the decrease of food and the increase of food prices, 1 100 million people will go hungry.

Climate warming will also aggravate the massive consumption of energy. Especially in cool summer, the impact on energy consumption is the most prominent. According to statistics, in industrialized countries, about 30% of energy in North America and 50% of energy in Europe are used to compensate for the effects of climate warming or cooling. During the period of 1984, due to the unusually hot weather in Southern California, the electricity consumption of refrigeration in September exceeded 85% of the normal electricity consumption, setting a 54-year electricity consumption record.

Climate warming also has adverse effects on trees, traffic, transportation and food. Due to heat and drought, forest fires will be more frequent and serious, and wood will be more scarce. More cars need to be equipped with air conditioners, which makes the average price of cars rise, and the dust generated by hot weather enters the engine in large quantities, resulting in vehicle damage and frequent maintenance; In addition, more roads need to be paved with asphalt, which will be more damaged in summer and need more money to maintain; Expressway will become more crowded because people will try to escape from the heat of the city more frequently.

According to scientists' prediction, 50 years later, the gradual warming of the earth will increase the destructive power of typhoons by 40% ~ 50%, which means that more houses, bridges and transmission lines will be doomed. Due to the above-mentioned chain disasters, food supply in many areas will be extremely short. The sharp rise in food prices will cause unemployment, depression and poverty, and the government budget and social welfare, scientific research and education funds will be greatly reduced.

Changes in human health

Due to the warming climate, summer will become very hot, which will lead to an increase in disease and mortality, especially for the elderly. According to research, the increase of ultraviolet B radiation caused by global warming and stratospheric ozone depletion will increase the number of patients with skin cancer, leprosy, cataracts, respiratory diseases, cardiovascular diseases and night blindness, among which Caucasians with fair skin in high latitudes may have the highest rate of skin cancer. Newborns may also experience negative growth, and the premature birth rate and perinatal mortality rate will increase. In addition, due to global warming, mosquitoes and other parasites will multiply in large numbers, and the diseases infected by them will be the epidemic situation in the world; Also, after the temperature rises, the number of skin diseases caused by mold will increase and the symptoms will become serious; Pests are rampant and pesticide pollution is aggravated. More than half of the world's population will be threatened by "climate diseases".

Changes of ecological species

According to historical records, there was a great temperature change 6,543,800 years ago, which led to the disaster of species: many temperate species fled to the north to settle in Canada due to a temperature rise of 5℃, and many animals and plants became extinct. The seriousness of the problem is that the extinction of these species at that time was caused by a long-term temperature rise of 5℃. Today, however, experts predict that it will only take 6 1 year for the temperature to rise by 5℃.

At present, cold-tolerant plants are the first to be threatened by global warming. According to the information provided by the Nature Conservation Foundation, global warming has put daffodils and other cold-resistant flowers at risk. 19 the rare and protected species "hang oxygen", and many plants are on the verge of extinction. Minor climate change is a disaster for plants. In the past 150 years, due to global warming, 96% of lowland swamps in the United States disappeared, 50% of old forest areas disappeared, and 9 1% of traditional lowland grasslands disappeared.

Recently, a report published by the World Wildlife Fund also said that coral reefs and Korean pine have been damaged due to the rising temperature of the earth, which will affect thousands of other plants and animals. With their death, the species that feed on them will not be able to migrate quickly to save themselves, and more than 22,000 species of plants and animals have been found to be endangered. Some migratory birds, butterflies and mammals are also threatened by global warming, and the ecological balance is seriously affected.

Ozone depletion

1985 In May, a British expedition first discovered an ozone hole in the atmosphere over Antarctica, which immediately attracted serious attention all over the world. Two years later, 1 10 more than one country in the world sent representatives to the international conference to save the ozone layer, and signed the famous Montreal Protocol on Substances that Deplete the Ozone Layer on June 1987. Protecting the ozone layer has quickly become a major international issue.

However,1at the beginning of April, 1992, more than 300 scientists from the United States, Russia, Britain, Canada and other countries 17 released a very bad news to the world: the ozone over the Arctic has been reduced to the lowest level on record, with a decrease of 20% only in the first two months of that year; The chlorine content in the Arctic stratosphere is 70 times higher than the normal level. This was discovered by scientists who participated in the "European Arctic Stratospheric Ozone Experiment" after five months of large-scale observation. As soon as this news was released, it immediately aroused the concern and panic all over the world, and protecting the ozone layer became the hottest topic for a time.

Almost three years later, at the same time, scientists announced a shocking new discovery: a hole appeared in the ozone layer over the Arctic, which was not as big as the ozone hole over the Antarctic, but the situation was similar.

Now, scientists agree that the ozone layer is destroyed by a man-made chemical commonly known as freon. Freon was invented in the 1930s. Their performance is extremely stable and generally does not burn. People always think that they are non-toxic and will not cause harm to the human body. Because of their high stability, they have a long life span and can be brought to the stratosphere of the upper atmosphere. There, under the action of ultraviolet rays, chlorine atoms are released, and the activity of chlorine atoms is very high, which quickly takes away an oxygen atom of ozone to form chlorine monoxide, which combines with another oxygen atom to form a new oxygen molecule and a chlorine atom, and the original ozone becomes an ordinary oxygen molecule and is retained. But oxygen molecules can't block ultraviolet rays. In this reaction, because chlorine atoms are not destroyed, the reaction of ozone depletion can be repeated. Therefore, the chlorine atom is like a "killer", destroying thousands of ozone molecules.

In fact, the distribution of freon over the earth is generally uniform, so why does the ozone layer only thin or even disappear over the north and south poles in winter? Scientists explain that this is because ice crystals in the stratosphere can accelerate the chain reaction between chlorine atoms and ozone molecules.

The destruction of the ozone layer has done great harm to life on earth. 199 1 At the end of the year, due to the appearance of the Antarctic ozone hole, sheep were temporarily blind, local pupils were allergic to skin, and unusual sun burns occurred in southern Chile. Scientists predict that if the ozone layer continues to decrease and thin at the current rate, by the year 2000, the global proportion of skin cancer will increase by 20%, reaching 300,000 people. If ozone decreases by 2 1 century 10%, the number of people suffering from cataracts in the world may reach 1.60 ~ 1.75 million every year.

Studies on some crops show that the increase of ultraviolet rays will affect the photosynthetic efficiency of plants. If ozone is reduced by 25%, soybean yield will be reduced by 6% ~ 25%, and protein content and oil content will also be reduced.

With the increase of ultraviolet rays, the harm to marine life is also significant. Scientists estimate that if ozone is reduced by 25%, the primary productivity of the upper ocean will be reduced by 10%, and the primary productivity near the water surface will be reduced by 35%.

Worryingly, chemicals that destroy the ozone layer, such as freon, are widely used in industrial products and daily necessities. Freon has penetrated into all aspects of human life since Dupont Company of the United States began to sell Freon refrigerants in the market 60 years ago. Freon is used in about/kloc-0.00 billion refrigerators and hundreds of millions of air conditioners all over the world. Freon is also contained in detergents used to clean electronic equipment, various sprays and foaming agents. It is estimated that the annual output of this kind of products is 750,000 tons, and the service life of freon is 50 ~ 100 years. Even if the production is stopped now, the concentration of chlorine in the stratosphere will continue to rise for some time, reaching its peak in 10 years 2 1 century ago. It will take at least a century to return to the natural level.

Human activities are the reason why freon enters the atmosphere. Now most countries realize that political decision-making is crucial to change this development process. Countries all over the world are joining hands to take effective measures to prevent the ozone layer from being further destroyed.