Amid global warming, China has witnessed more intensified and frequent scorching heat, affecting a broader range in recent years, a meteorological expert said recently.

"With the intensification of global warming, high-temperature weather in China in recent years is characterized by earlier onset, heightened frequency, prolonged duration, a wider impact range and increased overall intensity," said Zheng Zhihai, chief forecaster at China's National Climate Center.

"The first occurrence of regional high-temperature weather events nationwide is happening earlier by 2.5 days per decade," Zheng said, adding that between 1981 and 1990, the average onset of high temperature was June 24, advancing by 17 days to June 7 between 2011 and 2020.

The intensity and impact ranges of regional high-premature processes are also on the rise, with an average of 33 occurrences affecting 258 national meteorological stations per year between 1981 and 1990. This number increased to 4.1 occurrences affecting 328 national meteorological stations per year between 2011 and 2020, he said.

"Since the mid-20th century, the extent of climate warming in our country has been significantly higher than the global average for the same period, with a potential of an increase in the frequency and intensity of extreme high-temperature events becoming a new norm," he said, adding that the lagging effect of the El Nino effect and the onset of La Nina condition may lead to abnormal atmospheric circulating, bringing about regional high temperatures this summer.

El Nino, which started May last year and showed signs of ending at the end of last month, is bringing warmer air over the Pacific Ocean. It is expected to enter the opposite La Nina conditions later this summer, causing extensive cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean.

The National Meteorological Center has issued high temperature alerts for eight consecutive days since Friday evening. From Sunday evening to Thursday evening, the center elevated the yellow alert to orange in the three-tier, color-coded warning system for high temperature. Red represents the most severe level, followed by orange and then yellow.

An orange alert indicates that at least four provincial-level regions have experienced temperatures exceeding 37 C in most areas in the past 48 hours, with at least two of them experiencing temperatures over 39 C. In addition, temperatures are expected to remain above 37 C.

This year's first orange high-temperature alert came earlier-than-usual. Last year, the first orange alert was issued on June 22 and that of 2022 was issued on June 17. Notably, the average national summer temperature in 2022 was 22.3 C, the highest since 1961, followed by 22 C of last year.

"This summer, temperatures in most parts of the country are higher than usual for the same period, with an increased number of hot days and more frequent occurrences of prolonged hot weather," Zheng said, adding that areas such as North China, East China, Central China, South China and Northwest China's Xinjiang Uygur autonomous region may experience periodic heatwaves, with certain areas possibly facing extreme high temperatures.

In contrast to 2022 when high temperatures mainly affected areas in the Yangtze River Basin, this year's summer temperatures exhibit distinct periodic variations, with intense heat hitting North China and Henan, Anhui, Shandong and Jiangsu provinces in June. The heat is expected to travel southward in July and August, striking areas in South China and provinces like Shanghai, Jiangsu, Zhejiang, Anhui and Jiangxi, he said.

The heat wave, coinciding with the critical stages of summer harvesting and sowing, has brought significant impacts on major grain-producing areas in northern China.

The Ministry of Agriculture and Rural Affairs launched a Level 4 emergency response to major natural disasters on Tuesday, warning of the impact that persistently high temperatures and drought may have on crops such as corn and soybean in provinces including Hebei, Shanxi, Jiangsu, Anhui, Shandong, Henan and Shaanxi.

Yinan county in Shandong's Linyi carried out artificial hail suppression and rain enhancement operations on Wednesday afternoon, according to local media Linyi Daily.

In Henan, where national meteorological stations observed 43.4 C on Thursday in Wenxian county, Henan's Jiaozuo, the provincial meteorological center said preparations for artificial precipitation are ready. However, since this operation is dependent on specific natural conditions like clouds, the center is currently awaiting the right moment to proceed.

In addition, secondary disasters such as forest fires are prominent. The Ministry of Emergency Management, the National Forestry and Grassland Administration and the China Meteorological Administration issued a yellow alert for forest fire on Thursday, cautioning that insufficient rainfall and prolonged hot weather poses potential risks in Shanxi, Shandong, Henan and Hubei from Friday to Monday.