Problem description:
My family is from Anhui. I remember when I was a child, the river would freeze so thick in winter that pedestrians could even walk on it.
But now in winter, let alone leave, there is no thin ice. Why? Is global warming really so serious?
Analysis:
Global warming has certain factors, but it is mainly local. In the past, cities and suburbs were underdeveloped and there were few factories and chemical plants, which had little impact on the environment. But now there are factories everywhere, especially the pollution in cities is particularly serious, and a lot of carbon dioxide and pollution gases float over the cities.