Annual photosynthetic productivity can be reduced by as much as 20 days in areas where housing and commercial land use is very dense. For example, this was the case for arid and semi-arid areas where lawn irrigation and planting changed the ecosystems from shrub lands and desert to deciduous forests. A most interesting finding according to Imhoff was that urbanization seems to elongate the growing season, yet still reduces the overall productivity of the land. This could be demonstrating a profound urban heat island effect and have implications in climate change, especially in the northern Hemisphere where urban development is most intense. Analysis of the data also found clear evidence that human beings definitely tend to locate themselves on the most productive land and that those lands are being transformed into less productive types.
Human survival depends on photosynthesis.
If urbanization and industrialization continue, the capacity of the landscape to carry out photosynthesis is substantially reduced.