How do environmental & ecological issues constitute ethical challenges to business?

Environmental and ecological issues end up being ethical
challenges to businesses because the businesses have to figure out how much damage they
can ethically do to the environment or ecology in their pursuit of
profit.

Many businesses engage in practices that will, to
some extent, harm the environment.  This is unavoidable since any business that uses any
fossil fuels (for example) is harming the environment.  But there is surely some limit
as to how much harm is acceptable.  Businesses must consider this in their attempts to
be ethical.

As an example of this, businesses are currently
planning to extract oil from the "oil sands" of Canada.  This would be profitable but
would also help lead to global warming.  The firms must decide whether this level of
damage is acceptable -- it is an ethical challenge.