At present, the international discussion on climate change mainly refers to

At present, the discussion of climate change in the international community mainly refers to global warming.

1, climate change issues

Climate change refers to the statistically significant changes of climate mean and climate deviation, such as the changes of average temperature, average precipitation, maximum temperature, minimum temperature and extreme weather events. It is often said that global warming is one of the important manifestations of climate change.

The United Nations Framework Convention on Climate Change defines "climate change" as "climate change caused by human activities directly or indirectly changing the composition of the global atmosphere after a long period of observation."

This distinguishes "climate change" that changes the atmospheric composition due to human activities from "climate variability" attributed to natural causes. In the long history of earth movement, the climate is always changing, and the reasons can be summarized into two categories: natural climate fluctuation and human factors.

According to Luo Yong, deputy director of the National Climate Center, the causes of climate change may be natural internal processes, external compulsion, or man-made continuous changes in atmospheric composition and land use.

According to scientific research, changes in solar radiation, changes in the Earth's orbit, volcanic activity and changes in the atmosphere and ocean circulation are natural factors that cause global climate change.

However, human activities, especially those since the industrial revolution, are the main causes of climate change characterized by global warming, including greenhouse gas emissions such as carbon dioxide caused by human production and life, land use and urbanization.

2. Greenhouse effect

While absorbing the heat from the sun, our earth also emits infrared rays to dissipate heat. Oxygen and nitrogen, the main components in the atmosphere, cannot absorb infrared rays, and the infrared rays emitted by the earth can pass through them "without damage" to cool the earth.

However, some gas components in the atmosphere (such as water vapor, carbon dioxide, methane, etc. ) can absorb infrared rays and convert them into heat, which will increase the overall temperature of the atmosphere and eventually slow down the heat dissipation of the earth.

This phenomenon is called "greenhouse effect", and the gas that can bring "greenhouse effect" is called "greenhouse gas". It should be noted here that "greenhouse effect" is a neutral word, just a phenomenon, and there is no distinction between "good and bad". If there is no greenhouse effect, the average temperature of the earth's surface will be as low as-15℃, which is even less suitable for human habitation.