As global warming intensifies and precipitation increases in the north, will this cause more people to stay in the north?

★ It is not new that the temperature rises and precipitation increases in the north.

★ There are many factors that affect the flow of people, and climate is not the decisive factor.

Friends in the north may be particularly impressed by the heavy rainfall this year. A popular guess is that global warming will hopefully restore lush vegetation in northern China, making the climate more pleasant, and the population will return and grow.

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So, will the common sense of "hot and humid in the south and cold and dry in the north" really be overturned? Or is this just a normal fluctuation of the climate in a short period of time? Can the cold north really become the "biggest winner" in the context of global warming? Let's explore it below.

01

The North is indeed warming

But this is nothing new

my country generally uses the Qinling Mountains and the Huaihe River as the boundary to separate the south and the north. The north of this dividing line is a temperate monsoon climate, and the south is a subtropical monsoon climate. The average winter temperature in the north is below 0℃, with less precipitation and a short flood season; while the average winter temperature in the south is above 0℃, and the seasonal distribution of precipitation is much more evenly distributed than that of the temperate monsoon climate, and the flood season is longer, with precipitation generally exceeding 100mm from May to September.

Therefore, in the long-term production practice, people have formed the impression that "the south is hot and humid while the north is dry and cold". The severe weather of drought and cold seems to have become the biggest obstacle to the great development of industry and agriculture in the north. However, with global warming, meteorologists have noticed that a large amount of data is telling us that this "obstacle" is being disintegrated by reality at an alarming speed.

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With the development of modern meteorological observation methods and the accumulation of observation data, humans can now achieve fairly accurate weather forecasts and warnings for local weather in hours. By comparing and analyzing these trivial temperature and rainfall data on a larger time scale, we gradually find that the trend of global warming is "ongoing" in most regions.

However, from the perspective of geological history, such warming in the north is nothing new. According to the research of the famous meteorologist Mr. Zhu Kezhen, China's climate has changed over the past 5,000 years, spanning four warm periods and cold periods. The average temperature in northern my country has also risen sharply by about 0.7℃ in less than 2,000 years, which has directly led to a 20% increase in precipitation in the north. In the more distant 3 million years, scientists calculated through computer simulation that the overall temperature of the earth at that time rose by 2 to 3℃, and precipitation in the north suddenly increased by 30-40%.

Rising temperatures and more precipitation seem to be a good thing for the north, which has long suffered from cold and drought. A future with abundant forests and grasses and more conducive to agricultural production seems to be just around the corner. However, can this climate change really make more people choose to live in the north?

02

Simple climate change

It is difficult to reverse the trend of population migration to the south

As we all know, the amount of population moving from north to south in China has been huge in recent years. One obvious reason is that the winter in the north is relatively cold, which affects various economic activities.

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For example, in most parts of the Northeast, there is a long routine winter break in winter. During the winter break, most outdoor projects have to stop. The low GDP in the first quarter of the Northeast is also due to the impact of the winter break. If the climate warms up, the winter break will be shortened, the annual available construction period will be extended, and the project construction efficiency will also be improved. The local economic development speed will accelerate, driving the economic GDP to increase.

For the north, the winters in the past decade are far less cold than those decades ago, and the warming trend is very obvious. So, can the north, with its warming climate, reverse the trend of a large outflow of population to the south?

The answer may not be that optimistic.

Based on historical and current factors, the North, as my country's old industrial base, provides support for the South to undertake the processing of downstream subdivided industrial products through the production and processing of raw materials such as oil, steel, coal, and cement. As the upstream of the industrial layout, the growth rate of upstream industrial products that the North's economy relies on has continued to slow down in the past 20 years. At the same time, as the new force of "Made in China" marketed to the world, the growth rate of downstream industrial products in the South has continued to be strong.

The opposite development of industries in the north and south is the biggest driving force behind the population's migration. The large number of high-value jobs driven by industrial prosperity is like a huge water pump, continuously pumping the population southward.

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Compared with the realistic factor of such a large and solid regional economic division of labor that affects the southward migration of population, the current driving force of the northward migration of population caused by climate warming in the north on a smaller time scale seems insignificant.

In addition, according to the National Bureau of Statistics in 2019, the economic scale of the South has accounted for 64.56% of the national total economy, and 13 of the 20 regional hub cities in the country are located in the South. As an economic region that carries nearly 80% of China's industrial products and is a major trade hub, the South urgently needs a large number of people to participate in the operation of each link.

At the same time, the large population concentration has prompted the continuous development and integration of the Yangtze River Delta urban agglomeration, the Pearl River Delta urban agglomeration and the Yangtze River middle reaches urban agglomeration. The large influx of population has further accelerated the construction of major urban agglomerations, further interconnected regions, and made municipal facilities, education, medical care and other urban public products more abundant and efficient, which has further solidified this trend of population mobility.

So, can this trend change?

In the long run, global warming will also affect the Earth's atmospheric circulation, water and heat transport channels, ocean currents, etc., thus affecting global climate change in an all-round way. Such large-scale climate change will inevitably lead to changes in regional development and social and economic activities, which is the main reason for determining future population mobility.

Therefore, there are many factors that determine the movement of people. If we want to keep more people in the north, it is not enough to just change the climate.

03

Homes are built with hands

There are no winners in global warming

Some people may think that it is a good thing that the north has changed from cold and dry to warm and humid. The fact is that the cold in the north may be slightly alleviated by global warming. But the increasingly abnormal climate has brought greater troubles.

As mentioned above, warming in the north is nothing new. According to the latest scientific assessment report on climate change released by the United Nations Intergovernmental Panel on Climate Change (IPCC) in Geneva, Switzerland in August 2021, greenhouse gas emissions caused by humans such as fossil energy since the steam revolution in the 19th century have caused global temperatures to be 1.1°C higher than pre-industrial levels.

According to existing model predictions, the magnitude and speed of global temperature rise in the next twenty years will be far greater than in the past, and there is a high probability that it will exceed the critical 1.5°C that humans need to reverse the warming trend.

One consequence of this is extreme weather. For example, the rainfall in the north has definitely increased according to the data, but this rainfall is not evenly distributed. Instead, it is heavy rainfall in a short period of time, like the disasters encountered in Shanxi and Henan. Such rainfall brings disaster.

In addition, carbon dioxide is also a big problem. The United Nations Intergovernmental Panel on Climate Change (IPCC) came to a clear and cautious conclusion in its 2013 assessment report: the current climate warming phenomenon is most likely caused by the large-scale carbon dioxide emissions by humans since the Industrial Revolution.

The monitoring data of carbon dioxide concentration show that the concentration of carbon dioxide in the atmosphere has been rising exponentially since the Industrial Revolution. There is no doubt that as a tiny individual of human beings, we have more or less participated in this "century persecution" of the earth.

Since the Industrial Revolution, the concentration of carbon dioxide in the atmosphere has been rising exponentially.

(Image from Our World in Data)

We need to be aware that everyone is a participant in global warming. And facing the consequences of global warming, everyone will be a victim. The rise in global temperature is not just a disaster that will take decades or even hundreds of years to come, such as the melting of polar icebergs and the rise in sea levels. It is the increasingly frequent typhoons in summer, the rolling floods in the desert, the continuous rainstorms and droughts on the vast plains, and it is a common problem that affects every organism that depends on this planet to maintain life.

Building a beautiful home has never been a small blessing that can be achieved by living in seclusion in a warming climate, but should be a great wisdom of "I for everyone, and everyone for me".

Author: Liu Qiang, College of Environment and Resources, Zhejiang University

Review | Ai Wanxiu, Chief Expert Researcher, Climate Service Office, National Climate Center

Editor | Ding Zong

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