We're living on an earth. It is an imperfect world, but this is the only one we've got. If there are problems, we have to overcome together. In the world, there are many problems. For examples, climate change, COVID-19 pandemic, poverty, discrimination and nations confrontation. Every problem is big and large, they cannot be sorted out immediately and independently. However, the climate change is the biggest and largest problem among them. This is because if we cannot solve climate change as soon as possible, the result must be all creatures in extinction. Human-being creates climate change by Industrial activities, transportation and livestock ranches. They will generate and increase the emission of carbon dioxide to the world. In conclusion, climate change is the biggest environmental problem in the world. If we want to solve this problem, we have to work together. Eliminating the activities as I mentioned above, it is the first step we should do. That's one small step for man, one giant leap for mankind.