Original title: Global warming aggravates the instability of the climate system and the water cycle in the future?
Guangzhou Daily (by Yekas, an all-media reporter) This year, my country’s climate seems to be a bit turbulent. The formerly dry north was hit by heavy rains, while the rainy and humid Guangdong continued to experience little rain. Does this mean that the climate pattern of “northern drought and south flood” has changed? Climate experts are cautious about this. But what is certain is that changes in the frequency and intensity of extreme climate events will have a greater impact on the regional environment, economy and society.
Continuous rainfall caused successive floods in the Yellow River
In the eyes of people familiar with our country’s climate, this year’s climate is somewhat “southern but not north”. According to a report issued by the National Climate Center, since September, the northern region has had the highest precipitation in the same period in history. Under the influence of continuous rainfall, three consecutive floods of the Yellow River occurred within 9 days, all outside the traditional main flood season; at the same time, the southern region However, they suffered continuous high-temperature scorching. The number of high-temperature days in central and southern Jiangnan and central and northern South China exceeded 20 days, and the temperature in more than 10 provinces reached a record high.
From July 17th to 22nd, there was an extreme rainstorm in Henan Province, which lasted for 6 days. The maximum process cumulative rainfall observed in Zhengzhou is 993.1 mm; the maximum daily rainfall at the Zhengzhou National Observatory is 624.1 mm, which is close to the station’s annual average rainfall of 641 mm, which means that it is equivalent to nearly a year of rain in one day. The maximum cumulative rainfall observed in Hebi City reached 1122.6 mm, and the maximum daily rainfall reached 777.5 mm. During this extreme rainstorm, the daily rainfall of 19 national weather stations including Zhengzhou, Hebi, Anyang, Xinxiang, Luoyang, etc. exceeded the historical extreme value since the station was established.
In October, the rain belt “floated” to Shanxi again. From 20 o’clock on October 2 to 20 o’clock on October 6, the cumulative rainfall in southern Xinzhou, Luliang, Taiyuan, Yangquan, Jinzhong, Linfen, and Changzhi exceeded 100 mm, of which the northern Linfen and the southwestern part of Shanxi exceeded 200 mm. Most areas of Taiyuan, Yangquan, Linfen, Changzhi, Luliang, and Jinzhong have set a record of accumulated rainfall in the first ten days of October.
Guangdong launches emergency response to drought and water conservancy
In Guangdong, where the usual rainfall is plentiful, the rainfall this year has been on the low side. According to data from the Guangdong Climate Center, since this year (January 1st-November 11th), the average precipitation in Guangdong province has been 1308.0 mm, which is 24% less than the normal period in the same period and the fourth lowest in the same period in history. The accumulated precipitation in various places ranges from 653.1 mm (South Australia) to 2552.7 mm (Doumen), among which 7 counties (cities) including Longchuan, Boluo and Dapu broke the lowest record in the same period in history. The average temperature of the province is 24.0℃, which is 1.2℃ higher than normal in the same period, and is the highest in the same period in history.
Just a few days ago, Guangdong launched a Grade IV emergency response to drought and water conservancy. This is the second time that the Guangdong Water Resources Department has launched an emergency response to drought after the Pearl River Defense Directorate launched the emergency response to drought level IV on October 16. On the one hand, the Guangdong Provincial Department of Water Resources sets a reservoir water storage target to maximize water storage and preservation. On the other hand, the dynamic control of the operating water level of the reservoir during the flood season and the joint regulation of the river and reservoir are adopted to strictly control the outflow of the reservoir. The Department of Meteorology and Hydrology predicts that rainfall in the Pearl River Basin during the dry season of this winter and next spring may continue to be low, and the incoming water may continue to be low, especially the Dongjiang and Hanjiang rivers may experience extremely dry years, and the drought in some areas of the basin may gradually increase and the scope will be further expanded.
The shadow behind the anomaly of atmospheric circulation
Wu Hongyu, chief expert of the Guangdong Provincial Climate Center, told reporters that the reason for the lack of precipitation in Guangdong this year is that the subtropical high is generally stronger and the ridge line is significantly northerly. Guangdong is controlled by the subtropical high, and the cold air affecting Guangdong has been weak this year, resulting in the temperature deviation in Guangdong. High and obviously less precipitation.
From August 2020 to March this year, a moderate-intensity La Niña event occurred in the equatorial Central and Eastern Pacific. After the La Niña incident ended, the SST in the equatorial Central and Eastern Pacific began to develop into a colder state again in July this year, and entered the La Niña state in October. It is expected that a weak to moderate La Niña event will form again this winter. Under the background of La Niña, it is also conducive to the lack of precipitation in Guangdong.
Regarding the reasons for the rain in the north and the high temperature in the south this year, Zheng Zhihai, the chief expert of the Climate Prediction Office of the National Climate Center, said that this is mainly due to the combined effects of more active cold air activity and strong northerly water vapor transport. The strong and continuous warm and humid air from the south and the active cold air from the north frequently converge in the northern region, resulting in significantly more precipitation in the Yellow River Basin and Haihe River Basin; while the middle and lower reaches of the Yangtze River, Jiangnan and South China are under the control of subtropical high pressure, with high temperature and low rainfall. , The cumulative precipitation was significantly less than that of the same period in normal years, and some areas even experienced moderate to severe meteorological droughts.
Behind the strong northerly atmospheric circulation anomaly, it is the “La Nina” pushing hand.
Need to further enhance the awareness of disaster prevention and mitigation in all sectors of society
Wu Hongyu pointed out that since 1951, the annual average temperature in Guangdong Province has shown an obvious upward trend, and the annual precipitation has not changed significantly. Global warming makes the climate more unstable, and extreme weather and climate events occur frequently and increase in intensity.
Wu Hongyu said that global warming has caused droughts in the basin, rising sea levels in the South China Sea, increasing water use and destroying the ecological environment. Strong typhoons and storm surges have increased, threatening the safety of coastal areas, islands and reefs, and the ecological environment. Climate change has triggered an increase in extreme weather and climate events such as high temperatures, heat waves and floods, leading to injuries, deaths and diseases. Regarding the current meteorological drought, Wu Hongyu believes that meteorological drought monitoring and forecasting should be done, analysis and judgment should be strengthened, and favorable opportunities should be seized to carry out artificial precipitation enhancement operations.
In response to climate change, Wu Hongyu believes that basic work and technological innovation should be strengthened, awareness of the laws and mechanisms of climate change should be improved, prediction and forecasting capabilities and early warning information release capabilities should be improved; , To further enhance the awareness of disaster prevention and mitigation in all sectors of society, and increase the public’s knowledge and skills in disaster prevention and mitigation.
Future “Southern Drought”?
Can’t say that yet
Does such a “translocation” of climate mean that my country’s main rain belt is moving north? Ye Dianxiu, chief expert of the Climate Service Office of the National Climate Center, said that the distribution pattern of summer precipitation in my country has significant interdecadal changes. From 1950 to 1970, there was only one main rain belt, mainly located in the area north of the Yellow River. Since 1980, summer precipitation appeared in both north and south. The two rain belts showed a synchronous change trend. Before 2010, the two rain belts showed a trend of southward movement. After 2010, the rain belt began to show obvious characteristics of northward expansion and northward expansion.
Zhou Bing, chief expert on climate services of the National Climate Center, emphasized that it is not possible to infer the future trend of climate change based on extreme climate events in one, two, or one or two years. A signal of the transition from warm and dry to warm and humid. However, Zhou Bing pointed out that global warming has aggravated the instability of the climate system and the water cycle, making the atmosphere more unstable, increasing the efficiency of precipitation, and making heavy precipitation more significant. Extreme weather events are more sensitive to global warming. In the future, under the background of the same global warming trend, changes in the frequency and intensity of extreme weather events will have a greater impact on the regional environment, economy and society.
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