According to the monthly climate report released by the National Oceanic and Atmospheric Administration on September 14th, according to the data so far this year, there is a 93.42% probability that 2023 will become the hottest year on record.
For many people, this summer seems to be particularly long and unbearable. In the past few months, rare high temperatures above 40℃ have continued to appear in many places in China, followed by heavy rainfall and floods; Globally, many countries in South Asia and Southeast Asia ushered in extreme heat waves early in April-May; Mountain fires raged in Canada and Hawaii in the United States, and the casualties were the highest on record; The abnormal warming of seawater around Britain and Ireland threatens the survival of fish … …
However, this summer’s extreme weather may be just a preview of the future. In fact, the summer in the northern hemisphere is indeed extending. A study published in Geophysical Research Letters shows that if no measures are taken to curb global warming, by 2100, the northern hemisphere will spend more than half of its time in summer every year. The extended summer will not only bring longer high temperature, but also witness more extreme weather events such as rainstorm and mountain fire, which will also bring severe tests to phenology and agriculture.
"If the trend of global warming is not contained, the climate model forecast shows that there is the possibility that winter will disappear at some time in the future." Guan Yuping, a professor at south china sea institute of oceanology, told The Paper, "It’s hard to imagine what the earth will be like then!"
"Arrive early and leave late" in summer
Guan Yuping and his collaborators did this research by accident and curiosity, but the "unexpected" discovery attracted the attention of the whole world.
In this study, they analyzed the climate data of the northern hemisphere from 1952 to 2011 and found that the average length of summer has increased from 78 days to 95 days under the influence of global warming. If no measures are taken under the current greenhouse gas emission, by 2100, the summer in the northern hemisphere will be as long as six months, and the length of the other three seasons will be shortened.
And this summer’s high temperature "early arrival and late departure" is confirming this trend.
As early as the beginning of April, record extreme high temperatures appeared in Southeast Asia and South Asia. At the end of April, the temperature in southwest Europe and North Africa was 20℃ higher than the normal level in the same period of last year, reaching the high temperature level that is usually only available in July and August. Subsequently, new records of high temperature emerged one after another, and many authoritative organizations announced that July this year has become the hottest month on record on earth.
Until the end of August, 28 provinces in France still issued orange heat wave warnings, the temperature in some parts of the Middle East exceeded 50℃, and the high temperature record in central America was still being refreshed … …
In addition to the high temperature, this summer’s unusual extreme weather events such as hurricanes, mountain fires and droughts have also brought unprecedented damage.
This summer, after the continuous extreme high temperature in North China, the Haihe River Basin experienced the heaviest rainfall and the biggest flood in 60 years. The rapid transformation of drought and flood has not only broken people’s conventional understanding of the weather, but also made disaster prevention and emergency prevention more complicated.
In May, the first residents in Canada were forced to evacuate due to mountain fires. As of August 19th, there were still more than 1,000 mountain fires burning continuously, and they suffered the "worst" forest fire season in history. In the middle and late July, more than a thousand wildfires occurred in many places in Greece, causing air pollution equivalent to consuming 2.3 million barrels of oil; On August 15th, a mountain fire swept through Maui, Hawaii, USA. The worst mountain fire in the United States for more than a century caused 114 deaths and thousands of people lost contact, and the historic town of Lahaina was reduced to ashes … …
Premature continuous high temperature may be disastrous for human beings, animals and plants. The latest assessment of the United Nations Intergovernmental Panel on Climate Change (IPCC) shows that compared with before the industrial revolution, global warming of 1.5℃ will bring irreversible impacts on human beings and natural systems. As the global average temperature continues to rise, summer will start earlier and last longer, and the frequency of extreme weather events will also increase.
Phenology: biological rhythm that is no longer punctual
Abnormal seasonal changes and temperature changes also have a direct impact on biological rhythm. Flowering, Reproduction and Migration … … Everything in nature operates in an orderly way according to phenology, and climate change is disrupting this biological clock that has been calibrated in the past centuries of biological evolution.
The United Nations Environment Programme’s Frontier Report 2022: Noise, Fire and Phenology Mismatch points out that under climate change, not all species can evolve in the same direction and at the same rate. It is this mismatch that has a profound impact on the survival of species, and many species will become extinct.
A study published in the Proceedings of the National Academy of Sciences shows that global warming is making the spring in North America start earlier and earlier. Birds can’t keep up with this change, and if they deviate from the best breeding time, they will miss the most abundant opportunity in their habitat, resulting in fewer young birds.
In America and the Middle East, record warm winters disrupt the hibernation cycle of bears. Walking in the forest in winter, they not only face food shortage, but also pose a threat to the safety of surrounding residents and forestry workers.
The extension of summer caused by global warming has also contributed to the spread of infectious diseases. Studies have shown that when the water temperature rises, the time from egg to adult can be shortened from two weeks to one week; When the temperature reaches 26℃ to 31℃, the replication of Japanese encephalitis virus and dengue virus in mosquitoes increases compared with 20℃, and their infectivity is enhanced.
In fact, this effect is already happening. So far this year, more than 3 million cases of dengue fever have been reported in America alone. Dengue fever is spreading to areas where Aedes aegypti would not have entered. In 2015, Mexico City at an altitude of 2,240 meters recorded the invasion of Aedes aegypti for the first time.
The damage of sewage system and the interruption of drinking water caused by extreme weather events such as hurricanes, rainstorms and floods will also increase the risk of various pathogens. At present, driven by the unusually warm ocean, the hurricane season in the Atlantic Ocean has just begun to "wake up". On August 20th, California, usually unaffected by hurricanes, issued its first hurricane warning in 84 years.
Agriculture: Race against Climate Change
"Many farmers have reported that it is getting hotter and hotter now, or it is very hot early in the morning." Feng Qihua, a researcher on the impact of climate change on ecological small farmers, told The Paper, "For example, farmers in Pinggu, Beijing, had to cover themselves with quilts in the mountains at the beginning of June last year, but it was already too hot in June this year."
In order to investigate the impact of climate change and the accompanying abnormal weather, Feng Qihua and his colleagues visited 18 farms in Beijing, Tianjin and Hebei and South China from May 2022, and interviewed 28 ecological small farmers.
During her visit, she learned that due to the extreme high temperature in summer, many farmers had to change their working hours and go to work in the fields before 8 am and after 5 or 6 pm.
"(We) are racing against the speed of climate change now." She described it.
In addition, some farmers found that when winter is too warm or short, the base of overwintering pests increases, and abnormal temperature or precipitation changes break the population balance of pests and beneficial insects in the soil, so crops will be more susceptible to pests and diseases in spring.
However, in Feng Qihua’s view, the greatest impact on agricultural production is not the high temperature and summer extension itself, but the high uncertainty of seasonal change and extreme weather events. "The biggest problem with climate change is that the speed of warming is beyond the range that some systems can bear."
This not only means that it is difficult for farmers to arrange production according to the original traditional solar terms and phenological signals, but also means that crops are more likely to reduce production or commodity.
"If it is a natural climate change, time will usually happen slowly in hundreds of thousands of years, and animals and plants can often adapt to the environment or move to places suitable for survival, but now the speed of climate change caused by human beings is more than 100 years, which makes them far away ‘ Can’t keep up with the pace ’ 。” She said.
