A rare heat wave is raging in the northern hemisphere. At 6 o’clock on August 22, the Central Meteorological Observatory issued the highest level warning of high temperature in China-high temperature red warning for the 11th consecutive day. Not only in China, but also in Spain, Portugal, France, Britain and other places, heat waves with high temperature exceeding 40℃ have broken through historical extremes in many places, threatening human health, power supply, agricultural production and water resources.
Why is the heat wave coming? Will extreme weather become the norm in the future? According to the meteorologists interviewed, it is very rare to see the intensity and frequency of extreme weather this year. In addition to short-term direct meteorological factors, there has been a lot of evidence that this is closely related to long-term climate change. Climate change has once again sounded the alarm for the whole world.
High temperature and heat waves generally hit the northern hemisphere, and temperatures in many countries broke historical records.
The whole world is as cool and hot as this-at this moment, people in the whole northern hemisphere feel it particularly vividly.
"China has experienced the strongest high temperature process since there was a complete meteorological observation record in 1961. This process has the characteristics of long duration, wide range, high intensity and strong extremes." According to Zhou Bing, chief expert of climate service of the National Climate Center, as of August 21st, the duration of high-temperature events in China this summer (70 days), the coverage of high-temperature areas above 40℃ (1.5 million square kilometers), the maximum temperature intensity of a single station (45℃) and the number of stations with historical extremes broken or flat by the National Meteorological Station (330 stations) all set new records.
Looking around the world, the crimson and orange on the temperature map symbolize the high temperature weather above 35℃, which are widely distributed in Europe, North Africa, North America, East Asia and other places. In just one month, Europe experienced two rounds of heat waves. According to the World Meteorological Organization, the current heat wave sweeping Europe will continue, and the negative effects of climate change such as high temperature will last at least until the 1960s.
The decrease of river water level, the increase of forest and grassland fire risk, the drought of crops, the shortage of power and water resources … The heat wave brings not only somatosensory heat, but also a series of secondary disasters.
The unusually high temperature and rainfall are significantly less than in previous years, and the drought in many places in Europe is serious. "From the dry and cracked reservoirs in Spain to the drop in water levels of major rivers such as Danube, Rhine and Po, an unprecedented drought is sweeping across nearly half of Europe." The Associated Press reported that there was no obvious precipitation in most parts of continental Europe in the past two months, and some experts called it "the worst drought in 500 years".
The high temperature and drought caused the river water level to drop seriously, and the riverbed was exposed, making it difficult for ships to sail. The Rhine River is an important inland waterway in Europe, which flows through Germany, France, the Netherlands, Switzerland and other countries and is known as the "golden waterway". German federal and local waterway and shipping management agencies have warned many times recently that the waterway water level near many cities along the lower reaches of the Rhine River has set a new record, which has led to a sharp decrease in shipping volume and the actual load of ships is less than half of the normal situation.
Long-term high temperature combined with protracted drought has sharply increased the threat of forest fires. According to the data of the European Forest Fire Information System, more than 50,000 hectares of forests in France have been burned by fires this year, which is more than three times the average level in the past decade. Large-scale forest fires have also occurred in California, USA.
In the Po River region of Italy, severe drought caused rice fields to dry up and lack water. Local farmers estimate that this year’s rice harvest may be "halved". The German Farmers’ Association recently warned that in the case of continuous drought, we should be alert to crop failures and price increases. If it doesn’t keep raining as soon as possible, the harvest may be reduced by 30% or 40%.
Extreme high temperature also poses a threat to human health. "Heat will cause disease, and heat stress and high concentration of ground ozone will have a serious impact on health." Klaus reinhart, president of the German Medical Association, said about the impact of this wave of heat waves in Europe. The French health department warned that during the heat wave, the number of people seeking medical treatment increased significantly due to overheating and dehydration.
Climate warming intensifies the instability of the climate system and is more likely to lead to extreme weather and climate events.
Why is the high temperature event "long standby"? Meteorological observations can provide direct and short-term explanations. High temperatures are often caused by specific weather systems, the most common of which is subtropical high. The area under its control is prevalent in downward flow. On the one hand, air subsidence will compress and warm up; on the other hand, the upward movement is weak, and there is little rain in partly cloudy.
"The extreme high temperature in the northern hemisphere is caused by multiple factors, and the continuous abnormal atmospheric circulation is a direct cause." Zhou Bing told reporters that the western Pacific subtropical high belt, the Atlantic high belt and the Iranian high pressure have all been strengthened in stages, thus forming a large-scale warm and high pressure belt around the northern hemisphere, which makes the hot air stay near the ground and cannot be dispersed, and then there is a high-temperature heat wave event.
La Nina climate events have contributed to the atmospheric circulation anomalies. La Nina refers to the phenomenon that the seawater in the equatorial, Middle East and Pacific Ocean is unusually cold, which can cause changes in atmospheric circulation and then affect the climate. "Since this spring, the La Nina event in the equatorial eastern Pacific has intensified, and the SST anomaly in the Indian Ocean has pushed the subtropical high to continue to increase." Zhou Bing said.
Considering from a longer climate scale, global warming is the background of high temperature heat wave in the northern hemisphere. The long-term climate change caused by human activities is the deep-seated reason for the increase in the frequency and intensity of extreme weather.
"Climate warming will change the global ocean and atmospheric circulation situation, and further affect the local climate through the interaction between ocean and atmosphere, land and atmosphere. Climate warming intensifies the instability of the climate system and is more likely to lead to extreme weather and climate events. " Chao Qingchen, director and researcher of the National Climate Center, told the reporter that the overall feature of climate change is to aggravate the instability of the global climate, and the impact and risks on natural ecosystems and economic and social systems are becoming increasingly serious.
According to the sixth assessment report of the United Nations Intergovernmental Panel on Climate Change (IPCC), global warming is occurring at an unprecedented rate since 2000 in the last 50 years. The report released by the World Meteorological Organization shows that in the past 50 years, due to the impact of climate change, the number of disasters has increased fivefold and the disaster losses have increased more than sevenfold.
"Climate change has led to a trend of frequent, extensive, strong and concurrent extreme weather and climate events." Zhou Bing mentioned that the compound disasters caused by extreme weather are increasing. High temperature, heat wave and drought may occur more frequently, accompanied by the risk of wildfire; In some places, the possibility of compound flood has increased, and this possibility will continue to increase due to rising sea level and increasing precipitation intensity.
According to Zhou Bing’s observation, compared with several high-temperature events since the beginning of this century, this year’s heat wave has an obvious trend of advancing and strengthening in both the starting time and the extreme degree.
In the future, will the "hottest" become the norm?
According to the World Meteorological Organization, due to the influence of climate change, it is expected that extreme high temperatures will appear more frequently and more strongly in the future. Nalis, a spokesman for the organization, said that if greenhouse gas emissions continue to rise, global warming will be even greater, and what we are experiencing now is only a "harbinger of the future".
"Due to the intensification of global warming, the frequency of events such as extreme high temperature and extreme heavy precipitation has accelerated and the cycle has been shortened. The original once in 50 years has become once in 20 years or even 10 years. Every 1℃ increase in global temperature leads to an increase of 7% in extreme precipitation intensity. Every 0.5 C warming in the future will significantly change the frequency of extreme temperature events. " Zhou Bing said that the extreme high temperature staged in the world may herald the coming of the "40 C era in the northern hemisphere", but this needs further observation and scientific confirmation.
Rare extreme weather has sounded the alarm for the whole world, and it is urgent to deal with climate change.
The heat wave even rushed to the polar regions. "The temperature in Greenland is close to 60 degrees Fahrenheit (about 15.5 degrees Celsius), and warm weather like today is enough to wear short sleeves." On July 19th, in Greenland, an extremely cold place, a reporter appeared in the news screen wearing a thin T-shirt.
Greenland is the largest island in the world, most of which is located in the Arctic Circle, and about 80% of the island’s land is covered by ice sheets. This summer, the temperature in the Arctic Circle soared to 32.5℃, and the ice sheet in Greenland is melting at an alarming rate. According to data from the National Snow Data Research Center, from July 15th to 17th, the Greenland ice sheet lost about 6 billion tons of ice every day, enough to fill 7.2 million Olympic swimming pools. If the negative effects of climate change such as high temperature continue, the Greenland ice sheet will melt completely and the global sea level will rise by 7.5 meters.
In mid-March this year, the temperature in some parts of the Arctic was about 30℃ higher than the average level in the same period of last year. Many research stations in Antarctica have measured record high temperatures. The temperature at Concordia Antarctic research station is about 40℃ higher than the average level in the same period of last year, and the temperature at Kunlun Station in Antarctica in China has increased by 38.1℃ within 4 days. "The seasons in the north and south poles are opposite, but it is rare to see extreme hot weather at the same time. This is absolutely unusual." Zhou Bing said.
All kinds of unusual things have sounded the alarm for the whole world.
The research of Nobel Prize winners in physics, Shuro Kuniko and Klaus Hasselman, intuitively pointed out the relationship between greenhouse gas emissions and global warming: if the atmospheric carbon dioxide concentration doubles, the global average temperature will rise by more than 2℃. Accordingly, the Paris Agreement puts forward the goal of "keeping the global average temperature rise within 2℃ relative to the pre-industrial level by the end of this century and making efforts to control the global average temperature rise within 1.5℃".
Significantly reducing greenhouse gas emissions is related to the future and destiny of mankind. In 2021, the global average temperature was 1.11℃ higher than the pre-industrial level. In April this year, the IPCC said through the report of Working Group III in the Sixth Assessment Report that the world is at a crossroads where it is now or never. "If you want to control global warming within 1.5℃, you should either act now or never (fail to meet the standards), so all departments need to carry out deep emission reduction." Jim Ski, co-chairman of Working Group III, said.
"China has actively participated in global climate governance, implemented a national strategy to deal with climate change, promoted industrial restructuring and energy structure optimization, and accelerated the construction of a’ double carbon’ policy system, and achieved remarkable results in carbon emission reduction." According to Zhou Bing, in the past decade, China’s energy consumption intensity has been reduced by 26.2%, which is equivalent to using about 1.4 billion tons of standard coal less and emitting about 2.94 billion tons of carbon dioxide less. In 2020, China’s carbon emission intensity will decrease by 18.8% compared with 2015 and 48.4% compared with 2005, exceeding the target of 40%-45% promised to the international community.
The unbearable heat has also made people have a more real experience of global warming. "In terms of emission reduction, we often say that there are five levels: international social experience and mutual cooperation, national or regional independent contributions and policy-level attention, industry and enterprise carbon emission constraints and efforts, active participation of communities and the public, and scientific dissemination of green and low-carbon concepts of associations." Zhou Bing said that the public is not detached from the issue of climate change, and energy conservation and emission reduction require the joint efforts of all walks of life in the whole society.
Pay equal attention to mitigation and adaptation, enhance climate resilience and build a climate-adaptive society.
Reducing emissions is not the only action to deal with climate change. Mitigation and adaptation are two major strategies to deal with climate change, which complement each other and are indispensable.
"Mitigation refers to reducing greenhouse gas emissions through long-term adjustment of economic systems and natural ecosystems such as energy and industry. Adaptation refers to the climate change that has occurred and is expected to occur, through the adjustment of natural systems and human systems, to reduce the adverse effects of climate change on social and economic development and ecosystems, and to make full use of favorable factors. " Nest clearing dust said.
Slow down is the fundamental solution, but adaptation is also essential to solve the immediate problems. In the view of Chao Qingchen, the necessity can be understood from two aspects: first, climate change has already occurred, and its negative impact cannot be minimized if it is not adjusted and changed through adaptive means. Secondly, it takes time for mitigation measures to have an effect. Greenhouse gases have a long "life span". Even if emissions are reduced, past and present emissions will continue to affect the climate system, and the consequences will be manifested for a long time, such as sea level rising in the next few hundred years. Therefore, for the risks that have occurred and are about to occur, we must rely on adaptive measures to reduce the adverse effects.
China has always been adhering to the concept of paying equal attention to mitigation and adaptation, and taking active adaptation to climate change as an important part of implementing the national strategy of actively responding to climate change. Not long ago, the National Climate Change Adaptation Strategy 2035 was released, and it was proposed that by 2035, "a climate-adapted society will be basically completed".
Huang Gang, a second-level researcher in lasg, said in an interview with this reporter that according to the Action Plan for Urban Adaptation to Climate Change, the goal of building a climate-adapted city is to "significantly enhance the city’s ability to cope with waterlogging, drought and water shortage, high-temperature heat waves, strong winds and freezing disasters, and comprehensively improve its ability to adapt to climate change". "Similarly, a climate-adaptive society is a society with strong adaptability under changing climate conditions."
Try your best to prevent, focus on reducing, enhance climate resilience, and improve disaster prevention and mitigation capabilities. "Strengthening the early warning of extreme weather and climate events is the first line of defense for disaster prevention and mitigation." Chao Qingchen said that in the future, it is necessary to strengthen the comprehensive on-the-spot monitoring of extreme weather and climate and the understanding of the fine characteristics of disastrous weather and climate. Zhou Bing believes that global warming has brought new challenges to meteorological disaster prevention and mitigation, and it is necessary to continuously strengthen the disaster risk management ability of the whole society and the public’s awareness of disaster prevention and mitigation to minimize the impact of disasters.
Many interviewed experts said that in the face of increasingly frequent and intense extreme weather, we should not only focus on the present and solve the immediate problems, but also focus on the long-term and make a comprehensive response. For example, extreme weather affects agricultural production and energy supply, so we should take precautions and prepare adequate countermeasures. For another example, urban planning should take extreme precipitation and extreme high temperature into consideration, build infrastructure such as flood control and drainage systems that can withstand extreme weather, provide more shade places, and use more environmentally friendly and heat-insulating building materials.
The heat wave will eventually ebb, but the climate problem will not disappear, and extreme weather will not disappear. The challenges brought by climate change to mankind are realistic, severe and long-term, and each of us has the responsibility to "cool down" the earth.
(Author: Chai Yaxin Editor: Xu Nenyu)
