A lot depends on the actual degree you do. There are lots of degrees called Environmental Science, but are run by the departments of chemistry, physics, biology, ecology, engineering and economics. Mine is a chemistry degree with optional courses in water pollution, air pollution and ecology called 'chemistry and environmental systems'... so for me all chemistry jobs are open plus specifically environmental jobs. This is an important point. You are better of studying a particular subject that interests you and then applying that to the environment than taking a wishy washy environmental course that doesnt have much substance.
Most of the jobs I have done are environmental monitoring jobs, ie how much methanol is leaking into the river from the cooling system. Basically analytical chemistry applied to the environment. Their are many many environmental lab jobs going, but it sounds as if thats not your cup of tea.
Another major area is research and development where you will be designing future technologies that will help reduce our impact on the environment. This is where I am working now, designing the next generation of solar cells. This is esentially physics. To work in this field you need a technical degree...ie chemistry/physics/chemical ehgineering, mechanical engineering...what you have studied is less important than how technical it is.
The next largest group of jobs I see advertised are for carrying out environmental impact assessments. These have to be carried out now in most developed countries before large projects are allowed to begin. I worked in this field for a short time for the US Army and Airforce in Germany. We had to walk round the tank ranges recording the species we found which was very diverse as most of europe has been covered with fertilisers and pesticides but the US bases were kept natural. This then led us to indicate which areas were best to be used for shelling and which should be left quite.
A forth group of jobs can be seen from time to time and that is the environmental economists. The look at using the market to save then environment, ie how to change market incentives to make companies want to pollute less, ie carbon trading. Or work in ways to help locals in poor countries develop themselves without destroying their environments, ie poor people in central america cut down forest to plant maize to sell at the market, the economists go in and say farm iguanas instead, that gives them income from the pet trade and meat for the market, more than they would get from selling maize AND makes them want to keep the forests in a good state cause thats where the iguanas live.
If I was you I would avoid impact assessment as it is difficult to move on to other stuff and you can find yourself very constrained by politics. If you are into business as you say, Id go the economics route, but for me personally RandD ROCKS!!!!!
