Extreme high temperatures in the north are still continuing. How can summer harvest and summer planting be promoted?

This year's high temperatures in northern my country seem to have come a little early and lasted a little longer. As of the 16th, the central and southern parts of North China, the Huanghuai region, the central and southern parts of Shaanxi, and the northern and eastern parts of Xinjiang have experienced continuous high temperatures above 35 degrees Celsius for 4 to 8 days, with parts of southern Hebei, northern and western Henan, southwestern Shanxi, and northern Shandong reaching 40 to 42 degrees Celsius.

How did the strong high temperature in the north come about? How much impact will it have on agricultural production? How can various regions fight drought and ensure summer planting? We interviewed experts from the China Meteorological Administration and explained in detail the relevant issues that everyone is concerned about.

01. What meteorological factors are causing the persistent high temperatures in the north?

This round of high temperature weather is the most extensive and intense high temperature process in northern China this year. High temperatures in Hebei, Henan, Shandong and other places have lasted for a long time and the maximum daily temperature has been extreme.

Image source: China National Meteorological Administration

According to statistics from the National Climate Center, the comprehensive intensity of this round of high temperature weather process is the fifth strongest among all the high temperature weather processes in the country in the past five years, affecting nine provinces and cities including Beijing, Tianjin, Hebei, Shandong, Henan, Anhui, Jiangsu, Shanxi and Shaanxi, with an area of ​​about 850,000 square kilometers and a population of about 380 million. The highest temperature at a single station occurred in Wen County, Henan Province (43.4℃ on June 13).

The high temperature weather process in the northern region is mainly caused by the development of the continental high-pressure ridge . The clear sky radiation and downward warming have jointly promoted the development of high temperature weather.

From a climate perspective, periodic atmospheric circulation anomalies are the direct cause of the regional high temperature weather process. The high temperature in eastern China is mainly affected by the subtropical high pressure in the western Pacific and the warm high pressure in the westerly belt. In the areas controlled by the warm high pressure, downward airflow prevails, the sky is clear and cloudless, and it is not easy for clouds to form and rain. At the same time, the solar radiation is strong and the near-ground heating is intense. Under the condition that the high pressure system is abnormally strong and stable, it is very easy to form persistent high temperature weather.

02. Does this round of “heat wave” in the north indicate that my country will experience extreme high temperatures this summer?

Global warming is the climate background for the occurrence of extreme high temperatures around the world. Against this background, the frequency of summer high temperature events in North China, Huanghuai, Jianghuai, Jiangnan, and South China has shown a clear increasing trend. From 1981 to 1990, the average number of high temperature events in the country was 3.3 times per year, and from 2011 to 2020, it increased to 4.1 times.

According to the forecast of the National Climate Center, the temperature in most parts of China this summer will be higher than the same period of previous years, and there will be more high-temperature days. Among them, North China, East China, Central China, South China, Xinjiang and other places may experience periodic high-temperature heat waves , and some areas may experience extreme high temperatures. However, it is expected that the possibility of continuous high temperature and drought weather in the Yangtze River Basin similar to the summer of 2022 is small this year. This event is an abnormal weather event caused by multiple factors.

03. A moderate El Niño event formed in 2023. Is this related to this year's extreme high temperatures?

The latest monitoring by the National Climate Center shows that the Eastern El Niño event that began in May 2023 lasted until April 2024 and was confirmed to have ended in May. The intensity of this El Niño event was moderate, the fifth strongest in history since 1950 .

This El Niño event has a significant amplifying effect on global warming and regional or global climate anomalies, making extreme weather more frequent, more intense and more far-reaching in impact.

Monthly evolution of the Niño 3.4 index and the three-month moving average index (unit: °C) Note: The moving average of the SST index is the average of the SST index values ​​of this month, the previous month and the next month.

Image source: National Climate Center

Although the El Nino event has ended, its lagged impact is still ongoing. According to statistics, extreme weather will usually occur more frequently in the year after El Nino is formed. Compared with 2023, 2024 may be hotter, with more extreme weather. In the summer of 2024, the middle and lower reaches of the Yangtze River, the northern part of the northwest region and the northeast region of China face a high risk of floods, and North China, the eastern part of the northwest region and the southwest region are more prone to periodic high temperature and drought events.

04. Will the continued high temperatures in the north during the busy summer season have an impact on food production and supply?

At present, winter wheat in central North China and Northwest China is in the mature harvest period, and summer corn and summer soybeans in southern North China, Huanghuai and other places are in the sowing stage (after the winter wheat harvest is completed); spring-sown crops such as spring corn, rice, soybeans, and cotton in Northeast China, Northwest China, northern North China, the middle and lower reaches of the Yangtze River, and South China have entered a vigorous growth stage.

At present, the northern winter wheat areas are mainly sunny to cloudy, which is conducive to the filling and milky maturity of wheat and the mechanical harvesting and drying of mature wheat; the temperature in southern North China and most of the Huanghuai area is relatively high, and the soil moisture conditions continue to deviate, which is not conducive to the sowing and emergence of summer corn and summer soybeans.

Meteorological conditions are closely related to the occurrence and development of pests and diseases . Generally speaking, high temperature and drought are conducive to the reproduction and development of drought-loving pests such as locusts and aphids. On the other hand, drought can limit the growth of crops, weaken their resistance to pathogens and pests, and make them more vulnerable to pests and diseases.

According to the latest forecast of the Central Meteorological Observatory, high temperature weather will continue in North China and Huanghuai in the next few days, with the highest temperature in some areas reaching 42°C. High temperature will accelerate soil moisture loss , and the corn and soybean sowing progress and seedling growth in southern Hebei, southern Shanxi, eastern Shaanxi Guanzhong, most of Henan, western and southern Shandong, and northern Anhui are at high risk of suffering from high temperature and drought disasters, which may easily lead to seedling shortage and broken ridges.

Copyright images in the gallery. Reprinting and using them may lead to copyright disputes.

05. What work has the meteorological department done to ensure smooth agricultural production?

In response to this high temperature process, the China Meteorological Administration launched a Level 4 emergency response to major meteorological disasters (high temperatures) at 19:00 on June 9. On the 11th, the Ministry of Agriculture and Rural Affairs and the China Meteorological Administration jointly issued an agricultural high temperature and drought risk warning.

The National Meteorological Center has carried out progressive services and predicted in advance on June 6 that high temperatures will continue to occur in North China, the Huanghuai area and other regions. As of the 15th, it has issued high temperature warnings for nine consecutive days; strengthened coordination between the country and the provinces, conducted weather consultations with meteorological stations in North China, the Huanghuai area and other regions, and released products such as the National Agricultural Meteorological Weekly, providing impact analysis and response suggestions for agricultural production.

Meteorological departments in various regions strengthen targeted services and follow up with refined service products simultaneously - Henan Provincial Meteorological Bureau organizes field surveys and dry soil layer observations, and dynamically monitors the progress of wheat maturity and changes in soil moisture based on intelligent grid forecast products and multi-source remote sensing data, and produces and releases forecast products for the suitable harvest period of wheat and the suitable sowing period of autumn crops. At the same time, it makes preparations for artificial rainfall operations, and produces and releases regional and time-segmented mechanized harvesting weather forecast products based on the needs of mechanized harvesting; in Anhui, Jiangsu and other places, meteorological departments monitor soil moisture conditions on a daily basis, and forecast and predict the development trend of agricultural meteorological drought; in Shandong, the Provincial Climate Center strengthens drought monitoring and impact assessment, and holds joint consultations with agricultural and rural departments.

Author: Cui Guohui, reporter of China Meteorological Administration Meteorological Publicity and Science Center (China Meteorological News Agency)

Reviewer: Zhou Bing, Researcher at the National Climate Center, Chief Climate Service Expert at the National Climate Center

Produced by: Science Popularization China

Produced by: China Science and Technology Press Co., Ltd., China Science and Technology Publishing House (Beijing) Digital Media Co., Ltd.

The cover image of this article comes from the copyright library. Reprinting and using it may cause copyright disputes