I can think of several ways to justify that statement. First of all, if you are building new buildings, you generally need resources, right, such as wood, metals, plastics, etc. Those resources must come from some where….either manufactured, meaning chemicals usually released into the air in the form of green house gasses, or from the earth. Forests are harvested as wood resources; metals must be mined – clearing large areas of land and using fossil fuels to obtain/mine the metals, etc. You must have space to build, as another pointed out, which means acquiring land and reducing wild life habitat. Also, the building itself will drain resources in electricity consumption, water consumption, green house gas emissions. This is why there is a big push to build or renovate “green” buildings. Using sustainable and easily replenished materials or recycling, etc. Hope that helps some.

Um its not, Buildings are part of Earth, but if you mean building new buildings on what was once Woodlands, it is taking away the homes of defenseless critters like racoons songbirds possums deer and without the trees we get less oxygen and rain run off is more severe which leads to erosion.

Every time you add more concrete and steel in the environment, you add more heat.

Phoenix, AZ used to cool down at night… now, with all of the urban sprawl the temp. barely cools down at night.

Dirt and desert cools down… concrete and steel holds the heat.