In the Song Dynasty, in the land of the United States, there were many sources of carbon emissions. The country was vast, the industry was prosperous, the factories were numerous, and the machines were roaring day and night. This was a major source of carbon emissions. Coal, oil and other fossil fuels were consumed in large quantities in the operation of factory boilers and machines. Smoke billowed into the air, and carbon-containing exhaust gas filled the four fields.

And its traffic was also complex, with cars, trains, and planes shuttling back and forth. There were many cars, and when fuel was burned, carbide was discharged on the road; when trains ran long distances, they were powered by coal or fuel oil, and carbon emissions could be observed; when planes flew in the sky, fuel combustion caused carbon emissions to be emitted into the atmosphere at high altitudes.

Furthermore, the lives of residents also involved carbon emissions. Heating in winter and cooling in summer, relying on energy, either burning firewood or using electricity, and generating electricity relies heavily on fossil fuels, which indirectly generates carbon emissions. Cooking at home, the energy used is also at risk of carbon emissions.

And agricultural activities are also involved. Livestock raising, the genus of cattle and sheep, produces methane and other greenhouse gases during digestion, and is also one of the sources of carbon emissions. Farmland fertilizers are applied, and some fertilizers decompose and release carbon into the environment. In America, there are so many sources of carbon emissions, which are related to industry, transportation, people's livelihood, and agriculture. It is urgent to take good measures to control them.