La Nina phenomenon has been formed. Isn't it global warming? Why is it cold winter again?

The temperature dropped a little fast this year, and the Mid-Autumn Festival ushered in a big cooling. Many people witnessed the first snow in the winter of 2020 in tourist attractions, but the sudden cooling made many people unprepared and had to put on clothes in a hurry. This cooling caused many people to have doubts, and some people in the industry thought it was La Nina phenomenon, but soon the official denied that the cooling was not caused by La Nina, and the coldest in 60 years was just a rumor.

However, the report issued by the World Meteorological Organization pointed out that La Nina phenomenon has been formed, and it is expected that it will be moderate to strong this year and will last until 202 1, which will affect many parts of the world.

But La Nina? Winter!

1. What will La Nina do?

It refers to the decrease of the surface temperature of the Pacific Ocean and the eastern ocean, accompanied by the change of atmospheric circulation, which is contrary to the effect of El Ni? o phenomenon. Generally, when the temperature of a sea area is lower than 0.5℃ for three consecutive months, it can be designated as La Nina event. Once it breaks out, the rainfall in Southeast Asia and Pacific islands will be higher than in previous years, while in East Africa, it will be drier, which will easily lead to locust crisis, thus affecting food production.

Of course, La Nina's influence is different from year to year, and its influence on different regions is also different. Usually, it will make the global temperature drop, and it will also bring about problems such as rainstorm, drought and flood. But it is more harmful in the tropics, which may lead to a decrease in rainfall in Africa and North America, which is lower than in previous years. On the contrary, there will be more rainfall in Southeast Asia, South Asia and Australia.

Generally speaking, after the arrival of El Ni? o, La Nina usually appears once every 2-7 years, but its intensity has become weaker and weaker in recent years. It is understood that from August to September this year, the SST in the equatorial Middle East Pacific was lower than that in the same period last year, and the temperature also decreased with the change of time. The temperature monitored in September is 0.5℃ lower than that in previous years, which indicates that the formation of La Nina is expected to last until the first quarter of 20021year with an 85% probability.

Generally speaking, the duration of La Nina is 3 months, but in July of 1998, La Nina lasted for 24 months. Compared with previous years, the sea surface temperature is 65438 0-2℃ lower. Generally speaking, La Nina can cool down, but its cooling cannot change the warming caused by climate.

Second, the greenhouse effect seems to be more serious than La Nina.

The trend of global warming is becoming more and more obvious, and El Nino phenomenon is becoming more and more frequent. The arctic ice sea melts faster, and the snow on the plateau is also melting into spring water, so there is more probability of extreme climate. From 265438 to now, La Nina incident has been launched five times, and the strongest one should be in 2007-2008. There is a large-scale cooling and freezing phenomenon in the south, which has a great impact on China.

20 10-20 1 1, the average temperature in south China is 1.3℃ lower than that in previous years, which is also the lowest since 1986, causing the phenomenon that the southern region also suffers from freezing injury. In everyone's eyes, La Nina seems to have something to do with? Winter? The weather is linked, and once it appears, it will inevitably cool down. Actually, it is not. If there is a weak La Nina phenomenon, the winter temperature in South China will not decrease.

It is found that different types of La Nina have different effects on weather and atmospheric circulation. If there is a weak La Nina, it will still be hot in other places except the three northeastern provinces and Inner Mongolia. Judging from the temperature from June to September in 5438 this year, the world has reached a new high. According to the data of the European Meteorological Center, September ushered in the hottest 1 month in the world. In fact, La Nina appeared in August, but the temperature did not drop, which indicates that 2020 will remain one of the warmest years.

In fact, in the past five years, the temperature of the earth has increased year by year, mainly due to the greenhouse effect, more frequent natural disasters and more fragile ecosystems.

The sudden cooling in June 5438+10 and the snowfall in many places in Henan and Sichuan also made people shout that this year will be the coldest day in 60 years. Some people think that this year will be equivalent to the winter of 2008, but it is not. It is normal that the temperature drops in June 5438+ 10. After all, in June of 10, snowfall gathered in the northern or plateau areas, not every La Nina year.

This year's La Nina may cause the temperature in China to drop, but it is not enough to resist the temperature rise caused by the greenhouse effect, so it may continue to heat up this year. As for the exact weather, no one can say for sure, but only by forecasting.

Talas, Secretary General of the World Meteorological Organization, pointed out that La Nina usually has a cooling effect on global temperature, but the heat retained by greenhouse gases in the atmosphere is enough to offset this effect. Therefore, 2020 will remain one of the warmest years on record, and it is predicted that 20 16 to 2020 will be the warmest five years on record. The current La Nina year is even warmer than the previous years with strong El Ni? o phenomenon.

Third, the impact on agriculture.

La Nina has a great influence on agriculture. What is its performance in China? Leng Xia is hot in winter? Will it also be brought? Drought in the south and waterlogging in the north? Natural phenomena, accompanied by cooling and windy weather, low temperature, rainy weather and heavy snow will appear in some areas. According to the relevant information of the United Nations, this La Nina has a great influence on China, which may last for 4 months and the intensity is medium to high.

1, the influence of different regions

In the main grain producing areas in the east, there may be drought in the northeast next spring, and the precipitation is not too much. Farmers need drinking water for irrigation, and the drought in North China and Inner Mongolia may be more serious. In the western region, Yunnan and Guangxi are most affected by La Nina, and there may be a second flood. Therefore, farmers should pay special attention to planting crops and take preventive measures in advance.

There may be high temperature and little rain in the north, so we should pay attention to forest fire prevention. Affected by La Nina in the south, the weather may be warm and dry, and some areas may need to water crops in time.

2. Impact on agriculture

In the year when La Nina occurred, although the intensity and destructive power it brought were not high, it was necessary to pay attention to the growth of crops because of its long duration. In autumn and winter, crops such as wheat may not grow well due to lack of water and drought, and the growth cost of vegetables is high.

It is understood that in La Nina year, the price fluctuation of wheat was the most obvious, with a range of 56%. After all, La Nina will make the northern region suffer from persistent drought, and now is the growing season of wheat. Therefore, we should also pay attention to the prevention and control of winter wheat, avoid freezing wheat production at extremely cold temperatures, and also avoid it? Warm winter? A futile question.

Internationally, La Nina event will also have an impact on soybean production. Generally speaking, the climate is dry during the harvest period, and the yield per mu may decrease, which has a great impact on corn. There is a 50% probability that the yield of corn will decline, which will also reduce the yield per mu of sugarcane and increase the international raw sugar price.