“If it is like this, half of the year is summer… the northern hemisphere in 2100 is dangerous.”

If greenhouse gas reduction is not achieved, it is predicted that in the mid-latitude region of the northern hemisphere in 2100, half of the year will be summer and winter will be only one month.
As such, it is feared that if the beginning and length of the seasons vary greatly, it will have a great impact on human health as well as natural ecosystems.

Researchers from Lanzhou University in China and Beijing Academy of Sciences University in China recently published a paper in the international journal Geophysical Research Letters, saying, “If you follow a scenario that does not reduce GHG, the northern mid-latitude (30 North latitude) In the region of ~60 degrees), in 2100, summer can occupy almost half of the year,” he warned.

In the paper, the research team argued, “There have been cases where seasonal changes have been studied by region, but this is the first time that seasonal changes have been analyzed for the entire northern hemisphere.”

The research team first analyzed data on how long the seasons varied in the mid-latitude region of the northern hemisphere between 1952 and 2011.

To this end, the research team calculated the average temperature, which averaged the highest and lowest temperatures of each day, and regarded the days when the average temperature exceeded the 75th percentile as summer and the days within the 25th percentile as winter.
The rest of winter and summer were defined as spring and between summer and winter as autumn.

As a result of analysis based on these criteria, the length of summer in the mid-latitude region of the northern hemisphere increased by 17 days from 78 days in 1952 to 95 days in 2011.
Instead, it was found that spring was shortened from 124 days to 115 days, autumn from 87 to 82 days, and winter from 76 to 73 days.

Every 10 years, the summer was lengthened by 4.2 days, and the winter was reduced by 2.1 days.
In addition, the number of days decreased by 1 day every 10 years in spring and 1.1 days in autumn.

In addition, the start of spring and summer was advanced by 1.6 and 2.5 days, respectively, every 10 years.
Conversely, the start of autumn and winter was delayed by 1.7 and 0.5 days every 10 years, respectively.

Based on these seasonal changes, the research team predicted the future situation with a multiple ensemble model using CMIP5 (Coupled Model Intercomparison Projecr 5) and CMIP6.
In particular, the RCP 8.5 scenario, where there is no effort to reduce greenhouse gas emissions, was applied as business as usual.

As a result, it is predicted that by 2100, spring will start 3.3 days every 10 years and summer will start 4.6 days every 10 years earlier.
On the other hand, it is expected to be delayed by 3.8 days every 10 years in autumn and 1.4 days in winter.

Accordingly, it is expected that spring, autumn, and winter will decrease by 1.3, 2.4, and 4.7 days every 10 years, while summer is expected to increase by 8.5 days every 10 years.

According to this prediction, in 2100, summer begins around May 6 and ends around October 19, and winter begins around December 18 and ends around January 18, about a month later.
It means that summer will be 166 days and winter will stop on the 31st.

“Since all species cannot cope with seasonal changes in the same direction, seasonal changes can have a greater and greater impact on natural ecosystems,” the research team pointed out. “It can increase the burden of climate change on humans as well.”

Birds start breeding early with the onset of spring, but with the onset of summer sooner, the time to feed the chicks is shorter.
It can be difficult to reproduce.

In addition, as the plant growth period increases, the production of pollen that causes allergies increases, and the period when people suffer from pollen allergy also increases.
The virus-carrying mosquito’s habitat expands to the north, and the longer, hotter summers increase the likelihood of an explosive spread of the epidemic.

The longer the summer, the more heat waves occur, and as the atmosphere dries up, the risk of forest fires increases.
Frequent exposure to high temperatures can be harmful to your body as well as your mental health.

On the contrary, as winter shortens, crops cannot meet the’cooling amount’ (low temperature requirement) required for flowering, resulting in sluggish growth.
The yield decreases and the quality decreases.

The research team stressed, “As the length of the four seasons is expected to continue to change due to climate change, policies related to agricultural management, health management, and disaster prevention are needed.”

Staff Reporter Kang Chansu [email protected]