On August 7, the beginning of autumn, the Central Meteorological Observatory continued to issue a high temperature yellow warning - this is the 25th consecutive day that the station has issued a high temperature warning since the beginning of summer this year. At the same time, the temperature in most parts of the world is higher than the same period of the previous year, especially in the northern hemisphere Asia, Europe, North America and other places with frequent extreme high temperature events. In the face of the heat wave, everyone can't help but ask: Why is this year so hot?
Every summer, the high temperature will always swipe the screen in various postures. Last year, the topic of "stove city" became a topic of discussion after dinner. This year, it spreads with the overseas summer resorts of Northern Europe and the domestic summer resorts of Northeast China breaking high temperature records. Recently, it was reported that a rare high temperature occurred in the Arctic Circle, reaching 32°C at one point, causing the glaciers to melt rapidly.
Why is the high temperature this summer so "strong"? What is the reason for the "high fever" in many places around the world? Economic Daily reporters interviewed experts from the China Meteorological Administration.
Heatwave sweeps northern hemisphere
Since July, extreme high temperature events have occurred in many places in my country; at the same time, the temperature in most parts of the world is also higher than the same period of the year, especially in Asia, Europe, North America and other places.
Meteorologically, the daily maximum temperature greater than or equal to 35°C is defined as a "high temperature day". According to statistics, since the beginning of this year, the number of high-temperature days in parts of Jiangnan and South China has exceeded 20 days. Among them, the number of high-temperature days in western Huanghuai, central Chongqing, eastern Hunan, southern Jiangxi, southern Fujian, and eastern Guangdong has increased by more than 10 days compared with the same period of the previous year.
On August 2, Li Mingmei, deputy director of the Emergency Disaster Mitigation and Public Service Department of the China Meteorological Administration, revealed at a regular press conference that in the past July, the national average temperature was 22.9°C, 1°C higher than the same period of the previous year. Extreme high temperature events occurred at 94 meteorological stations across the country, including 24 meteorological stations in Benxi County, Liaoning Province (39.2°C) and Ji'an City (38.4°C), and the daily maximum temperature broke through historical extremes.
In fact, my country's high temperature weather phenomenon is not "outstanding". Since July, temperatures in most parts of the world have been warmer than normal. Among them, northern Europe, western and northeastern Asia, and northwestern and central North America are 2°C to 4°C higher; especially in the northern hemisphere, extreme high temperature events occur frequently in Asia, Europe, and North America.
"Denmark is scorched" - the European Space Agency released a set of satellite images on July 25 under the title. The picture shows that a farmland on the Danish island of Zealand was still green in July 2017, but in July this year, the local vegetation has been "scorched", and brown has become the main color of the picture.
Data released by the World Meteorological Organization shows that the Nordic region is experiencing continuous high temperatures, with temperatures in the Arctic Circle exceeding 30°C, and high temperatures of 33.5°C and 33.4°C in Norway and Finland, respectively. Sweden has reported about 50 forest fires in mid-July due to unusually dry weather; parts of the UK have been hot and dry this summer, setting records for the driest summer in half a century, causing lawns to yellow and reservoir water levels to drop rapidly.
Due to the high temperature and strong winds in recent days, Greece, which is located in southern Europe, has also experienced frequent forest fires recently. On July 23, Athens, the capital of Greece, was hit by a high temperature of 40°C. A forest fire near the city has injured hundreds of people.
Heavy rainfall and heat waves also hit Japan one after another. In early July, persistent torrential rains in western Japan killed many people. Since then, continued high temperatures have appeared in most parts of Japan, with the highest temperature exceeding 40°C in some areas. According to statistics from the Fire Department of Japan's Ministry of Internal Affairs and Communications, in the week from July 16 to July 22, more than 22,000 people were sent to the hospital for heatstroke. In addition, many places in South Korea have also issued high temperature warnings.
And the high temperature weather in many North African countries is even more hot - in early July, Morocco experienced a high temperature of 43.4 °C, and the highest temperature in the Sahara Desert in Algeria even reached 51.3 °C. According to the World Meteorological Organization, this should be the highest recorded in reliable temperature records for Algeria.
North America was not spared from the heatwave either. The weather station in Death Valley National Park, California, USA, measured a high temperature of 52 °C on July 8; the continuous high temperature and humidity in Quebec, Canada has caused many deaths.
Global warming is the main cause
Experts said that global warming has increased the risk of high temperature, which is the background of this year's abnormal high temperature and heat wave. But under the general trend of global warming, the rate of warming in each region is not the same
Experts from the World Meteorological Organization believe that although it is difficult to simply attribute the recent extreme weather to climate change caused by human activities, from the perspective of long-term impact, the trend of global extreme high temperature and increased precipitation is undoubtedly caused by climate change. result.
"From the perspective of climate background, global warming has led to increased risk of high temperature, which is the background of this year's abnormal high temperature and heat wave." But Ai Wanxiu, chief of the climate service room of the National Climate Center, believes that the trend of global warming does not mean that every All regions are warming at the same rate.
She said that the rate of global temperature rise is asymmetric, as shown in the following: First, the rate of warming in the north is higher than that in the south, and the extremes of high temperature in the Arctic this summer are higher than those in the low latitudes; second, the rate of increase in the minimum temperature is higher than The rate of rise of the maximum temperature. Although the number of high temperature days in my country this year is the third since 1961, the minimum temperature is the highest since 1961. A high minimum temperature means nighttime temperatures don't get cooler, adding to the heat.