Before letting the Earth wander, let’s study this more realistic threat

During the Spring Festival of the Year of Guimao, "The Wandering Earth 2", a New Year's film that can be regarded as a milestone in Chinese science fiction films, has grossed over 3.3 billion yuan in just 15 days after its release, becoming one of the must-talk topics among friends and family.

My first feeling after watching it: shocking.

In fact, movies are not just about sensory stimulation, they also involve questions that go straight to the soul and the thoughts behind them.

1

Can humans really withstand the test of climate change?

What will happen to forest resources under climate change?

The World Meteorological Organization's Climate Change 2020 report diagnosed the worsening "ecological condition", with words such as "unprecedented", "record-breaking" and "continued warming" appearing from time to time in the report. 2020 is one of the warmest years on record, with global temperatures rising by 1.2°C compared to pre-industrial times (1850-1900).

This means that there is only 0.8℃ space left to achieve the 2℃ temperature control target of the Paris Agreement.

Shrinking Arctic glaciers and helpless polar bears

Image source: Internet

2

Why is it necessary to limit the temperature rise to 2℃?

What changes will a 2°C increase in temperature bring to the Earth?

In 2008, the "2°C Target" assessment report released by the European Union Climate Change Panel pointed out that if the global average temperature rise is controlled within 2°C, human society can still take measures to adapt in real time to reduce the environmental, social and economic losses caused by climate change to within the human tolerance range; once the temperature rise exceeds this threshold, humans will be unable to cope with it.

If the surface temperature rises by 2°C, the global water shortage will nearly double; high temperature will increase evaporation, making it impossible for electrolytes that should be dissolved in water to be discharged into the sea, and they can only be precipitated on land, which will cause soil salinization and a sharp drop in the yield of food crops such as corn and wheat.

Soil salinization (A), glacier melting (B) and reduced grain production (C)

Image source: Internet

In addition, warming in the Arctic will cause ancient viruses that have been sealed in the permafrost for thousands of years to be released into the environment, which may cause great damage and immeasurable disasters to our life, health and ecological security.

At present, 2°C may be the last grace period that nature will give to humans. If the global temperature rises to 3°C, the temperature in the Arctic and Antarctic may rise by 10°C, at which time 80% of the ice sheets will melt and the sea level will rise by another 45 meters. This will be self-evidently harmful to the developed coastal cities of almost all countries.

Glacier melting in different regions under the background of global warming

3

How to slow down global warming has become

Major scientific issues that need to be solved globally

Reducing the Earth's greenhouse gas emissions while increasing vegetation's fixation of CO2 is considered an effective way to mitigate global climate change.

In the terrestrial ecosystem, forests occupy an important position due to their strong carbon fixation capacity. As an important part of the "life community of mountains, rivers, forests, fields, lakes, grasslands and sands", they are the largest carbon storage and the most economical carbon absorber. Therefore, they are also called climate regulators and buffers for controlling global warming.

The income and expenditure of forest carbon is like the storage of cash in a bank. Forests can store CO2 through plant photosynthesis, and some of it will be released through the respiration of plants and soil. Of course, plant death, fire, pests and diseases, logging, etc. will also cause the forest to release some carbon. The remaining net stored CO2 is called a forest carbon sink. Forest carbon sequestration utilizes natural processes, does not require high costs, and has ecological benefits such as protecting biodiversity, conserving water resources, and preventing wind and sand.

According to the 2020 Global Forest Resources Assessment by the Food and Agriculture Organization of the United Nations, the global forest area accounts for about one-third of the global land area, and the carbon storage of forest vegetation accounts for as much as 77% of the global vegetation carbon storage, up to 662 billion tons. It is worth noting that human deforestation or unreasonable logging will cause the carbon stored in the forest to be released back into the atmosphere.

At present, my country's forests as a whole are at a stage dominated by young and middle-aged forests, and their growth is relatively vigorous. This helps to increase the carbon sink of my country's terrestrial ecosystems and plays a significant role in the multiple measures to reduce greenhouse gas emissions.

Therefore, people often say that protecting forests is beneficial to the present and future generations. Protecting existing forests, including reducing forest death and forest degradation caused by fire, pests and diseases, can continuously increase carbon sinks and reduce greenhouse gases, which is also an important way to protect the earth.

END

Author: Nie Xiuqing: Institute of Forest Ecology, Environment and Nature Conservation, Chinese Academy of Forestry

Assistant Researcher

Editor: Guru