The highest temperature in Guangdong in the 1990s.

A, the more obvious direct cause of urban heat island effect is that the temperature difference between urban and suburban areas increases and the urban temperature rises. During this period, Shanghai's urban population is increasing, so it does not meet the problem.

B, in the process of urbanization, industry, automobile exhaust, population density and greenhouse gas emissions directly lead to temperature rise. So, it is correct.

C, the urbanization process reduces vegetation, water vapor evaporation and transpiration, so the heat consumption is reduced, so it is correct.

D, urban heat island is obviously mainly related to heat dissipation and less heat consumption, and it is impossible to know whether the local circulation is strengthened, which does not meet the meaning of the question.

Therefore: BC