Century, the strongest, "La Niña" caused a severe drought swept across the northern hemisphere (Photos)

In northwestern France, a drought-induced water shortage is serious.
Some European countries, rivers have dried up.

Germany, France, Britain, United States, China ... ... the first half of 2011, a rare drought swept across the northern hemisphere countries and regions, people's lives and industrial and agricultural production have been severely affected. Drought in the past, some countries took place floods. 

This rare cause of climate catastrophe that? How should human beings deal with similar extreme weather disaster? 

Create a record drought 

8th of this month, according to Xinhua News Agency, the World Meteorological Organization in Geneva issued a statement that from January to May this year, suffered persistent drought in most parts of Europe. Especially February to May this 4-month total precipitation, the equivalent of half a century from 1951 to 2000 average of 40% over the same period to 80% in parts of Western and Central Europe and even less than 40%. 

The drought in many countries to create a record: in Switzerland in 2011 was the driest since 1864, the 10 one year; in France this year, January to April is the driest since 1975, the month; in Germany, this spring a century is the driest spring, most of the river water level dropped to the lowest point century; in southwest England, in March of this year was the driest since 1953 in March. 

Drought losses are heavy. In the central and western Europe, because the average temperature rise with reduced precipitation, increased evaporation, resulting in severe seasonal water balance. 

World Meteorological Organization said, the growth status of crops in Western Europe is far worse than normal year; Rhine reduce the water level has affected the shipping; Netherlands, Germany, Britain and other countries, the highest risk of forest fires; French 26 provinces announced restrictions on water use. 

The United States as severe drought. Since this spring, the U.S. central and western and southern states, most of the 9 region experienced 20 to 50 years for a return of the "extreme drought" in Texas and Louisiana suffered a small part of the region for 50 years to once in 100 years The most serious level of "exceptionally dry." The long duration of the drought not only agricultural production, also increased the risk of forest fires. 

Severe drought in Northeast Asia 

In Northeast Asia, drought is not an isolated phenomenon. In China, the Yangtze River suffered a hundred years in parts of the large area of ​​drought. 

In the Korean peninsula, KCNA said North Korea this year, continuing throughout the drought, precipitation is the lowest since 1977, have a negative impact on agricultural production. 

Exception is the main cause of climate drought 

What factors led to such a rare drought in the northern hemisphere? Experts generally believe that this rare behind the drought, global climate change occurred in the context of the "La Nina" and other anomalies. 

World Meteorological Organization in Geneva on May 23 issued the bulletin shows that in spring last year to this year's "La Niña" caused a disturbance of the climate in some parts of the world, droughts and abnormal. 

"La Nina" also known as the "anti-El Niño phenomenon", refers to the central and eastern Pacific, cold water anomaly, resulting in the humid air pressure over the Pacific Ocean is low. "El Nino" is that this part of the abnormal warming sea water. The "La Nina" began in mid-July last year, peaked in January this year, in February began to weaken in May before entering the regression phase. 

Scientists believe that, from the central and eastern Pacific sea temperature variation, the "La Nina" medium strength, but the sea level pressure, wind, cloud and other atmospheric conditions change, this is because the strongest in a century "La Nina the phenomenon of "one. 

Unusual strength of the "La Nina", often accompanied by global climate anomalies. Central and southwestern United States, for example, mainly for temperatures higher than in the past, rainfall decreased. For East Asia, mainly for the continent over the existence of a stable high pressure zone, the humid air over the Pacific Ocean bring rain can not flow to the mainland. Once the "La Nina" weakening, the Pacific sea temperature rises, the pressure over the moist air, and will bring abundant precipitation in the mainland, or even result in the so-called "Drought and rapid change." 

Drought for Europe, the World Meteorological Organization explained that over the western and central Europe this spring, there is also a rare stable high pressure zone, preventing moist air over the North Atlantic to the European continent rainfall. Currently, the European drought has not completely alleviated. 

In a broader context, the "La Nina" and "El Nino" occurs frequently in succession, hurricanes, droughts, floods and other disastrous weather, the frequency increases, increasing destructive power, is an important indicator of global warming. The United Nations Intergovernmental Panel on Climate Change has long been recognized since the mid-20th century, average global temperatures rise, caused by human activity is likely to increase in carbon dioxide emissions caused. (Xinhua News Agency) 

Irrigation facilities is the "drought hero" 

Reservoirs, dams and other water conservancy facilities, what role in the worst drought? Whether, as some people imagine, and promote the formation of a drought? In this regard, the experts give a clear answer: the drought is not an isolated phenomenon, and spread to Europe, Asia and North America countries. Drought irrigation facilities is not only the "culprit", on the contrary, mitigate droughts, floods and other extreme weather caused by disasters, "hero." Sri Lanka - Berkeley National Laboratory in Norman Miller and others, "Geophysical Research Letters," published an article that the Three Gorges reservoir, the reservoir area of ​​the sinking moist air to leave the "no net change." This means that precipitation in the lower reaches of the reservoir area will not be affected. 

Takes a similar view that the University of Tennessee, Associate Professor of Civil and Environmental Engineering, Faisal Hussein. He told Xinhua that the reservoir or the dam itself on the local climate, especially precipitation is extremely small. 

Ukraine Odessa Hydrometeorological Institute Natalia Liu Bardon in an interview with Xinhua, said that theoretically, the reservoir can only be slightly affected small-scale climate, will not cause much of the climate anomalies, so Yangtze River Three Gorges Reservoir is not the main reason for the drought. 

In fact, through the rational allocation of reservoir storage to regulate river flows, water conservancy facilities is not only a "drought hero" dramatic changes in drought and flood, flood damage, also has a flood control function. Liu Bardon said that, like the Three Gorges reservoir that not only does not cause an artificial drought, but can be released more water to increase the flow of rivers alleviate the drought hazard. 

Many countries have recognized that, through new construction, renovation of water conservancy facilities, and improve their operation, may slow in the foreseeable future extreme weather disasters. In the United States, U.S. Department of Interior report released in April this year that the Western response to future water shortages, they planned to transform the Hoover Dam.