In most parts of China, Leng Xia is hot, and there are four distinct seasons in winter. It is generally reported that the temperature in winter is getting higher and higher in recent years, and it seems that it is not as cold as before. In fact, not only in China, but also in the world. Not in recent years, the temperature has been rising continuously since the 1980s. Due to global warming, precipitation increases in winter, and abnormal high temperature and severe drought occur in summer. The number of rainstorms in some areas has increased, the global glaciers have decreased, the snow area in the northern hemisphere has shrunk, and the sea level has risen by an average of about 2.5 mm per year. 1995 In the summer, the United States experienced a once-in-a-century heat, not only many people were killed in the heat wave, but also two accidents caused by the thermal deformation of the railway tracks. There is also a cool summer in most parts of Europe, and the highest temperature in many places reaches 40℃.
Global temperature rise will have a direct destructive impact on human beings: sea level rise will flood many cities and lands, the destruction of ecological balance will lead to reduced agricultural production, and the migration of insects and other infectious animals will bring harm to human health.
Why is the climate getting warmer? Over the years, scientists have done a lot of observation and research. Many scientists believe that global warming is caused by human activities. A large number of gases such as carbon dioxide, methane and nitrogen oxides are emitted in human production activities, which makes the atmosphere absorb more heat like a greenhouse and raise the temperature. However, some scientists put forward different views. They pointed out that there have been many cold-time changes in the history of the earth, and the current warming is only a natural change in the temperature of the earth. It is still difficult to determine whether it is man-made influence or natural change.
The latest nature: paying attention to global temperature rise
In the latest issue of the British journal Nature, an international research team composed of multinational scientists published a research report, saying that global warming will lead to the extinction of terrestrial plants in the next 50 years. In other words, more than 1 10,000 species will disappear from the earth in half a century.
Scientists from eight countries studied 1 103 species in Europe, South Africa, Australia, Brazil, Mexico and Costa Rica. These include plants, mammals, birds, reptiles and insects. According to the estimation of the United Nations, the global temperature may rise by 0.5 to 3 degrees Celsius by 2050. They use computer models to calculate the impact of temperature rise on each species. This is by far the largest similar study.
Global warming has forced most land species to migrate to the polar regions and mountains, but many animals and plants can't do this. According to scientists' conservative estimation, by 2050, the species in these six areas will disappear by 65,438+05% to 37%, that is, on average, 26% species will be extinct because of rising temperature and the inability to find suitable habitats.
In addition, global warming will lead to the spread of various diseases and viruses, and ultimately affect people's health.
Global temperature rise will do more harm than good to mankind.
Global warming is an indisputable fact. How to deal with the challenge of global warming to human living environment is one of the themes of the international scientific seminar on climate change being held in Beijing. Professor Obasi, Secretary-General of the World Meteorological Organization, pointed out that climate change gives us another reason to take urgent action immediately.
At present, the most urgent thing is that we still lack a basic understanding of global warming, and what will change when the temperature rises. Ding, special adviser on climate change of China Meteorological Bureau, said that climate warming will bring some beneficial effects, such as: due to rising temperature, crop yield in some parts of mid-latitude may increase; Global timber supply may increase; For residents in some water-deficient areas, the available water may increase; Due to the cold winter, the mortality rate of residents in middle and high latitudes has decreased; Because of the warm winter, the energy needed for heating is reduced. But the impact on the national economy is mainly negative.
-Planting bears the brunt. Climate warming will increase evaporation, and if the precipitation does not increase obviously, the farming-pastoral ecotone in China will expand southward. The boundary between the farming-pastoral ecotone in Northeast China and Inner Mongolia will move south by about 70 kilometers, the boundary between the farming-pastoral ecotone in North China will move south by about 150 kilometers, and the boundary between the farming-pastoral ecotone in Northwest China will move south by about 20 kilometers, thus increasing the grassland area. However, the farming-pastoral ecotone is a potential desertification area, and desertification is a huge threat.
After climate warming, the microbial decomposition of soil organic matter will accelerate, which will lead to the decline of soil fertility and the need to apply more fertilizers; Climate warming is also beneficial to insects and weeds, which makes the application of pesticides and herbicides increase.
-the cost of agricultural production will be greatly increased. By 2030, affected by global warming, the crop yield in China may be reduced by about 5% ~ 10%, mainly wheat, rice and corn. When the annual average temperature increases by 1℃, the number of days with national accumulated temperature greater than 10℃ will be extended by 15 days on average. The northern boundary of safe planting of winter wheat will also be moved from the current Great Wall Line to Shenyang-Zhangjiakou-Baotou-Urumqi Line. By 2050, climate warming will move the northern boundary of triple cropping system 500 kilometers north, from the Yangtze River basin to the Yellow River basin; However, the double-cropping rice area will be moved northward to the middle of the current single-cropping area, and the area of single-cropping area will be reduced by 23. 1%.
Water will become less and less and dirtier. Global warming will affect the whole water cycle, which may increase evaporation, change regional precipitation and its distribution pattern, increase the occurrence of extreme precipitation events, increase the frequency and intensity of floods and droughts, and change surface runoff.
The natural annual runoff of seven major river basins in China shows a decreasing trend. Among them, the annual runoff of the Yangtze River and its south area changes little; The Huaihe River and its north area have the largest change, the Liaohe River basin has the largest increase, followed by the upper reaches of the Yellow River, and the Songhua River is the smallest. Global warming will also increase the annual average evaporation in various river basins in China, and the evaporation in the Yellow River and inland rivers will probably increase by about 15%.
In dry years, the water shortage caused by climate warming will greatly aggravate the water shortage situation in North China and Northwest China, and the impact on agricultural irrigation water is far greater than that on industrial water and domestic water, especially in areas where precipitation decreases and evaporation increases. It is estimated that the water shortage in the western region will be about 20 billion cubic meters from 20 10 to 2030, and it will be10 billion cubic meters in 2050. Global warming will make precipitation variability change with the increase of average precipitation, and evaporation will also increase with the increase of global average temperature, which may mean that the frequency of droughts and floods will increase in the future.
Due to the increase of evaporation, the river flow tends to decrease, and the original pollution degree of the river may increase, especially in the dry season. At the same time, the rise of river water temperature will also promote the deposition of pollutants in the river and the decomposition of waste, thus reducing water quality.
-personal quality of life will decline. The direct impact of climate warming on human health will be more obvious. High temperature makes viruses, bacteria, parasites and allergens more active, and it will also damage people's spirit, human immunity and disease resistance. The increase of high temperature and heat wave will increase heat-related diseases and deaths. The adverse effects of global warming on human health have the greatest impact on the population in poor areas.
Climate warming has an impact on human settlements. Floods and landslides are the most common and direct threats faced by residents living in riverside and coastal areas. At present, human habitation is facing environmental problems including water and energy shortage, garbage disposal and traffic, which are aggravated by high temperature and rainy weather. Cities in low-altitude coastal areas with high population density are often threatened by extreme coastal climate events. In China, most residents' income comes from the primary resource industry dominated by climate, and the adverse impact of climate warming on China will be more serious.
Scientists question
Existing methods to curb global warming
After studying the carbon emission and absorption of terrestrial ecosystems in the past 20 years, scientists believe that the so-called "carbon deposition" effect may be only temporary and cannot be relied on to curb global warming for a long time.
"Carbon deposition" means that vegetation absorbs more carbon dioxide than they release, which helps to reduce the concentration of atmospheric carbon dioxide and alleviate the trend of global warming.
Thirty scientists from Europe, the United States and other regions said in the upcoming issue of the British journal Nature on the 8th that the carbon deposition effect of the earth's vegetation was unstable, and the data of carbon dioxide and oxygen content in the atmosphere confirmed that the earth's biosphere absorbed and emitted almost the same amount of carbon dioxide in the 1980s, and there was no carbon deposition, but there was a certain deposition effect in the 1990s.
Data show that the carbon deposition effect in 1990s mainly appeared in non-tropical areas of the northern hemisphere, including North America, China and Europe. Scientists believe that the main reason for carbon deposition may be the conversion of farmland into forests in the above areas. In addition, the reduction of forest and grassland fires reduces the carbon released by vegetation, which also contributes to carbon deposition. Changes in photosynthesis, respiration, pests and other factors may lead to the reduction of carbon released by leaves, dead plants and soil microorganisms.
Scientists say that increasing the concentration of carbon dioxide in the atmosphere can increase the growth rate of plants, thus absorbing more carbon and temporarily enhancing the carbon deposition effect, but this effect will eventually reach saturation. There are many unstable factors affecting carbon deposition. In the long run, the global terrestrial biosphere may not continue to play a role in carbon deposition, especially in warm and dry years.
Forests cannot save global warming.
Global Times (version 16, June 8, 2006, 5438+0)
In summer, when people are worried that the temperature is getting higher every year, a group of scientists in the United States gave people another blow. Their latest research shows that in order to stop the rising trend of temperature year by year and solve the threat of greenhouse effect, human beings have to find another way instead of placing high hopes on forests as before. Because a large amount of carbon dioxide absorbed by forests will eventually return to the earth. The greenhouse effect is listed as one of the biggest threats facing mankind in the 2 1 century. It not only makes the weather hotter and hotter, but also brings a devastating blow to a large number of species in wetlands, coastal lowlands, coral reefs and temperate cold regions around the world. Tracing back to the source, the greenhouse effect is a weather phenomenon caused by excessive accumulation of carbon dioxide in the atmosphere. It has long been known that green plants absorb a lot of carbon dioxide through photosynthesis, so forests have always been regarded as a sharp weapon to solve the greenhouse effect. On May 24th, Nature published the new experimental reports of several botanists and ecologists from Duke University. Seven years ago, these scientists chose two forests near Duke University campus and started an experiment to evaluate the ability of trees to absorb carbon dioxide. It is estimated that by 2050, the amount of carbon dioxide discharged into the atmosphere will increase by 35%-50% compared with the present. Therefore, in the first group of forests, they constantly release gas with a carbon dioxide concentration of 560ppm(ppm is one in a million) to simulate the concentration level after 50 years; The second group of forests maintains the current normal carbon dioxide level, that is, the concentration is about 365ppm. In the first two years of the experiment, the growth of trees in the first group of forests was obviously accelerated under high concentration of carbon dioxide, and the growth rate was about 25% faster than that of trees in the second group of forests. But after two years, the growth rate decreased rapidly in a short time, and finally it was basically the same as that of the trees in the second group of forests. The main reason is that the nutrients in the soil, especially nitrogen nutrients, are exhausted with the rapid growth of trees. The experimental results show that trees need sunlight, moisture, nutrients and other factors, and forests can accelerate the absorption of carbon dioxide in the short term, but in the long run, forests can not be expected to digest 50% of carbon dioxide after 50 years. In addition, after tracking and observing the role of carbon dioxide in the growth of trees, scientists found that carbon dioxide absorbed by trees mainly plays a role in the growth of leaves, not in the trunk. The most fatal consequence of this is that the leaves will slowly rot after falling off, and almost all the carbon dioxide absorbed by them will return to the atmosphere within three years, instead of staying in the soil as people said before. David Esworth, a professor of biology at Duke University who presided over the experiment, commented on this result: "If this result is generally confirmed in global vegetation ecology, people will have to rethink environmental issues." At present, experiments show that the absorption capacity of tropical trees for carbon dioxide is lower than that of trees in other regions. The outside world has paid great attention to this report. A botanist at the University of Illinois in the United States said that the "potential importance" of this result will become more and more obvious, which completely subverts people's traditional ideas. Although forests play an irreplaceable role in water conservation, soil erosion prevention and climate regulation, people should not be too optimistic about their ability to digest a large amount of carbon dioxide. Ram Olin, another ecology professor who participated in this experiment, believes that this is the importance of the experimental results. He said that perhaps people can only solve the problem of greenhouse effect by reducing the emission of carbon dioxide gas, which will make the global environmental protection problem more complicated and the conflict of interests more acute. Reducing carbon dioxide emissions has always been an extremely sensitive issue in the world. Last year, the International Environmental Protection Conference in The Hague ended in discord, and the key issue in the dispute between the United States and Europe was the carbon dioxide emission standard. The United States insists that the emission limits of developed countries should take into account the absorption of carbon dioxide by forests. If this factor is taken into account, we need not be too pessimistic about the prospects after 50 years, and the requirements of developed countries for carbon dioxide emission standards need not be too harsh. Now, this latest experimental result can be said to have hit the key of the United States. If so, the United States will not be able to use forests as an excuse to evade its responsibilities, and the world can only further strictly limit carbon dioxide emissions, which will directly affect the economic development of all countries in the world.
Microorganisms can "eat" greenhouse gases, and global warming has something to eat.
Jiangnan Times (August 200212nd edition15th edition)
Comprehensive news of this newspaper Many scientists from Germany claimed that they found a life form that feeds on methane in the Black Sea, and said that this life form can be used to curb the further deterioration of global warming. These scientists say that the life they discovered this time is the oldest life on earth, with a history of 4 billion years. They found this microorganism in the depths of the Black Sea without light and oxygen, and found that these microorganisms feed on methane. Until now, scientists have always believed that methane can only be consumed by reacting with oxygen. These German scientists hope that these microbes can be used to "eat" greenhouse gases still stored below the earth's surface. A lot of methane is still frozen under the polar ice, but with the intensification of global warming, it is likely to be released, making the pollution problem more serious. Professor AntjeBoetius, one of the sponsors of this research activity, said: "These microorganisms found in the Black Sea may be the oldest inhabitants on the earth. We may rely on them to prevent climate disasters. "
New measures to slow down global warming
-Throw iron into the sea
China Environment News 200 1 1 13.
Scientists in New Zealand have recently proposed a new solution to global warming: increasing the iron content of seawater in the South Pacific. With the increase of iron content in seawater, plankton and phytoplankton will grow rapidly. The New Zealand Institute of Water and Atmospheric Research (NIWA) published the research results in the journal Nature.
A long time ago, scientists wanted to make aquatic plants in the South Pacific grow rapidly by increasing the iron content, just like forests and grasslands on land, which played an important role in reducing the carbon dioxide content in the atmosphere. As a result, scientists scattered 2 tons of decomposed iron in more than 50 square kilometers of the South Pacific, which increased the iron content in water by 10 times. Within two weeks, plankton increased by 10 times compared with that outside the sowing area. The South Pacific Ocean accounts for 15% of the world's ocean area and plays a vital role in the global climate, but its iron content is low. After NIWA scattered iron, the photos taken by NASA every six weeks show that the spread area of phytoplankton has reached 1 100 square kilometers. The sustained growth time of phytoplankton exceeded people's expectations. Scientists believe that this may be due to the ability of phytoplankton to release special substances into seawater in order to absorb iron. Satellite images vividly show the sensitivity of the South Pacific biosphere to a slight increase in iron content.